Cellular Pleomorphism Research Articles

Efficient Production of Melanin by Aureobasidium Melanogenum Using a Simplified Medium and pH-Controlled Fermentation Strategy with the Cell Morphology Analysis.

Natural melanin is a biopolymer with wide application prospects in medicine, food, cosmetics, environmental protection, agriculture, and so on. Microbial fermentation is an important and effective way to produce melanin. In this study, Aureobasidium melanogenum, known as black yeast with cellular pleomorphism, was used for the production of melanin. Based on the characteristic of A. melanogenum secreting melanin under oligotrophic stress, a simple medium containing only glucose, MgSO4·7H2O, and KCl was constructed for the production of melanin. The melanin titer of 6.64 ± 0.22g/L was obtained after 20 days of fermentation without pH control. The cell morphological changes of A. melanogenum during the production of melanin were recorded, and the results showed that chlamydospore might be the most favorable cell morphology for melanin synthesis. Then, different fermentation strategies with cell morphology analysis were developed to further improve the production of melanin in a 5-L fermenter. Results showed that the maximum titer of melanin reached 18.50g/L by using the fermentation strategy integrating pH control, ammonium salt addition, and H2O2 stimulation, which increased by 178.6% than that of the strategy without pH control. Furthermore, the melanin obtained from the fermentation broth was characterized as eumelanin containing an indole structure. This study provided a potentially feasible fermentation strategy for the industrial production of melanin.

Deciphering glioma epitranscriptome: focus on RNA modifications.

Gliomas are highly malignant tumors accounting for the majority of brain neoplasms. They are characterized by nuclear atypia, high mitotic rate and cellular polymorphism that often contributes to aggressiveness and resistance to standard therapy. They often associate with challenging treatment approaches and poor outcomes. New treatment strategies or regimens to improve the efficacy of glioma treatment require a deeper understanding of glioma occurrence and development as well as elucidation of their molecular biological characteristics. Recent studies have revealed RNA modifications as a key regulatory mechanism involved in tumorigenesis, tumor progression, immune regulation, and response to therapy. The present review discusses research advances on several RNA modifications involved in glioma progression and tumor microenvironment (TME) immunoregulation as well as in the development of adaptive drug resistance, summarizing current progress on major RNA modification targeting strategies.

A Weakly Supervised Deep Learning Model and Human-Machine Fusion for Accurate Grading of Renal Cell Carcinoma from Histopathology Slides.

(1) Background: The Fuhrman grading (FG) system is widely used in the management of clear cell renal cell carcinoma (ccRCC). However, it is affected by observer variability and irreproducibility in clinical practice. We aimed to use a deep learning multi-class model called SSL-CLAM to assist in diagnosing the FG status of ccRCC patients using digitized whole slide images (WSIs). (2) Methods: We recruited 504 eligible ccRCC patients from The Cancer Genome Atlas (TCGA) cohort and obtained 708 hematoxylin and eosin-stained WSIs for the development and internal validation of the SSL-CLAM model. Additionally, we obtained 445 WSIs from 188 ccRCC eligible patients in the Clinical Proteomic Tumor Analysis Consortium (CPTAC) cohort as an independent external validation set. A human-machine fusion approach was used to validate the added value of the SSL-CLAM model for pathologists. (3) Results: The SSL-CLAM model successfully diagnosed the five FG statuses (Grade-0, 1, 2, 3, and 4) of ccRCC, and achieved AUCs of 0.917 and 0.887 on the internal and external validation sets, respectively, outperforming a junior pathologist. For the normal/tumor classification (Grade-0, Grade-1/2/3/4) task, the SSL-CLAM model yielded AUCs close to 1 on both the internal and external validation sets. The SSL-CLAM model achieved a better performance for the two-tiered FG (Grade-0, Grade-1/2, and Grade-3/4) task, with AUCs of 0.936 and 0.915 on the internal and external validation sets, respectively. The human-machine diagnostic performance was superior to that of the SSL-CLAM model, showing promising prospects. In addition, the high-attention regions of the SSL-CLAM model showed that with an increasing FG status, the cell nuclei in the tumor region become larger, with irregular contours and increased cellular pleomorphism. (4) Conclusions: Our findings support the feasibility of using deep learning and human-machine fusion methods for FG classification on WSIs from ccRCC patients, which may assist pathologists in making diagnostic decisions.

MALIGNANT STRUMA OVARII (KASUS LANGKA)

Struma ovarii (SO) are rare and accur in 2-3% of mature ovarian teratomas, most SO cases are benign. Malignant struma ovarii (MSO) is even more rare and occurs in 0,5- 5% of all cases, with the most common histologies identified are papillary and follicular carcinoma, most commonly affect patients in their 4th to 6th decade of life. Due to the rarity of malignant transformation, data about its management are lacking. A 49-years-old woman P2A0 with abdominal pain and pelvic mass, admitted for a hysterectomy and bilateral salpingo-oophorectomy. The left ovary was measured 13x11x5 cm, cystic and partly solid, filled with gelatinous fluid, composed of thyroid follicles with the appearance of "ground glass", "nuclear inclusion" and "nuclear groove", forming a papillifer structure. The diagnostic of MSO is based on histological features include cellular atypia, increased hyperplasia, nuclear pleomorphism, mitotic activity, vascular and/or capsular invasion. To be classified as a MSO, teratoma containing 50% or more thyroid tissue. MSO necessitates surgical staging for ovarian cancer with pelvic washings, total abdominal hysterectomy, bilateral salpingo- oophorectomy, lymph node sampling, total thyroidectomy, and radioactive I-131 ablation. Based on the clinical examination and histopatological examination the patient was diagnosed with MSO (ICD O: 9090/3).

Myxofibrosarcoma of Head and Neck Region in a Patient with Follicular Carcinoma of Thyroid

Myxofibrosarcoma (MFS) is a malignant fibroblastic tumour with variable myxoid stroma, cellular pleomorphism and curvilinear vascular pattern. It is commonly seen in late adult life, peaks in the seventh decade and usually occurs in the lower extremities. MFS of head and of the neck is extremely rare and accounts for approximately 1% of all head and neck neoplasms. A fifty two year old lady with follicular carcinoma thyroid treated six years ago, presented with a rapidly increasing neck swelling in the left supraclavicular fossa. Fine needle aspiration cytology of the cervical node was suggestive of metastatic carcinoma and she underwent left posterolateral neck dissection. Histopathology and immunohistochemistry was suggestive of high grade myxofibrosarcoma with negative margins. She was treated with adjuvant radiotherapy and has been under regular follow up for 6 months.

Cyto-Architectural Complexity of Dyshormonogenic Goitre can Closely Mimic a Thyroid Follicular Malignancy: A Case Report and Review of the Literature to Avoid Diagnostic Pitfall

A 13-year-old male child presented in the OPD with a midline 5x4cm thyroid swelling of 2 years duration with the chief complaint of difficulty in breathing. He also had growth and mental retardation since 3 years of age. His thyroid profile records revealed a severe degree of hypothyroidism and he was on thyroxine supplement since then. He underwent a right hemithyroidectomy for the right-sided nodular goitre causing on-and-off dyspnea. The gross specimen measured 5x4x3cm, which on cut section showed partially encapsulated multi-nodular solid areas. Microscopy yielded marked architectural complexity and prominent cellular and nuclear pleomorphism that mimicked a thyroid malignancy; for eg., a poorly differentiated papillary or follicular carcinoma. However, a thorough assessment of a range of histo-morphological features in the context of clinical history clinched the diagnosis of dyshormonogenetic goitre. One year postoperatively the patient is doing well on Thyroxine supplement. This case report reviews the literature about this rare benign entity of dyshormonogenetic goitre which closely mimics thyroid malignancy, notably a follicular malignancy on microscopy owing to its cytoarchitectural complexity and nuclear atypia. Hence, knowledge of its clinical presentation, gross and diverse microscopic features is extremely important to avoid misdiagnosis and thereby clinical management.

Marcadores de proliferação celular e de apoptose como fatores preditivos à eletroquimioterapia em carcinoma de células escamosas cutâneo de gatos

ABSTRACT: Determining cell proliferation rates and tumor apoptosis through immunohistochemistry allows the evaluation of the biological behavior of the tumor, optimizing the patient’s clinical course. This study aimed to analyze the immunohistochemical expression of Ki-67, COX-2 and caspase-3 and correlate them with the type of response to ECT in feline cutaneous squamous cell carcinoma (SCC), thus determining the predictive potential of these variables. For this, 13 samples of feline cutaneous SCC were evaluated before ECT, and statistical analyses of the correlation intensity between the variables were performed using the Spearman correlation coefficient, with a significance level of 95%. The results indicate a significant negative correlation between histopathological grade and response to ECT (ρ=-0.6; p=0.03); there was no significant correlation between Ki-67, COX-2 and caspase-3 immunoexpression with the response to ECT (ρ=-0.18; p=0.54/ρ=-0.23; p=0.44/ρ=-0.12; p=0.69, respectively). Therefore, the study shows that the histopathological grade, tumor size and staging, degree of cellular pleomorphism and degree of inflammatory infiltrate can be considered negative prognostic factors for cutaneous SCC and negative predictors for response to ECT. However, the markers Ki-67, COX-2 and caspase-3 are not considered predictive factors for the type of response to ECT. In addition, no relationship between these immunoexpressions and greater tumor aggressiveness was observed. The SCCs evaluated in this study showed significant COX-2 labeling, indicating a potential therapeutic target. ECT has been shown to be safe and effective for local control of feline cutaneous SCC but with reduced effectiveness in larger and invasive lesions.

Multifocal Malignant Epithelioid Mesothelioma of the Testis

Abstract Introduction/Objective Testicular mesothelioma is an extremely uncommon entity, and presents with non-specific clinical symptomatology, including painless scrotal enlargement and hydrocele formation. Testicular mesothelioma arising from the mesothelial cells of the tunica vaginalis accounts for 0.3%-5% of all mesothelioma cases and is often associated with poor prognosis. While the pathophysiology of this entity remains unclear, exposure to asbestos and long-standing hydrocele are associated risk factors. Methods/Case Report Herein, we present a case of a 65-year-old male with history of hypertension, 4-year history of left scrotal hydrocele, and a 7-month history of painless, progressively enlarging left scrotum. Scrotal ultrasound revealed a left, septated hydrocele with multiple heterogenous intratesticular masses. A left radical orchiectomy was performed and the specimen was sent to pathology for histopathological evaluation. Gross examination revealed a tan-brown fluid-filled cystic and solid mass measuring 7.5 x 4.0 x 3.5 cm involving the entire epididymis with multiple pink-tan, friable, papillary excrescences and nodules in the intratesticular parenchyma. Microscopic examination revealed a cystic and solid lesion with tubular and papillary architecture comprised of cuboidal cells with cellular pleomorphism, irregular nuclear contour, and dense chromatin involving the epididymis, rete testis, tunica albuginea, the testicular parenchyma including the hilar fat and the spermatic cord stroma. Immunohistochemical staining of the lesion demonstrated positive staining with AE1/AE3, CK7, WT1, PAX8, Calretinin, Vimentin, Podoplanin D2-40, and lack of staining with Chromogranin, Inhibin, MART-1, SMA, AFP, CD99, S100, c-kit, PLAP, HCG, MOC31, BerEP4. Based on the histomorphology and the immunophenotype of the lesion, a diagnosis of an epithelioid-type malignant mesothelioma was favored. Results (if a Case Study enter NA) N/A. Conclusion Malignant epithelioid mesothelioma of the testis is a rare and important clinical consideration for patients presenting with scrotal lesion, non-specific clinical presentation, and a history of asbestos exposure and/or long- standing hydrocele.

PSAT198 Atypical Parathyroid Adenoma is an Unusual Cause of Primary Hyperparathyroidism

Abstract Background Atypical parathyroid adenomas (APA) are considered tumors of uncertain malignant potential and have a biochemical and clinical phenotype that is generally more aggressive than typical parathyroid adenomas (PA). Low incidence as an etiology of primary hyperparathyroidism (PHPT) presents a challenge in understanding the pathological features and natural history of APA. We present a case of PHPT due to an APA and review the published literature for these tumors. Case A 37 year-old male was referred for evaluation of hypercalcemia, with serum calcium level 13.6 mg/dL (8.6-10.3). Repeat serum calcium measurement was 12.7 mg/dL, and two measurements of intact PTH were 870 pg/mL and 919 pg/mL (12-88), respectively. The patient's laboratories raised concern for parathyroid carcinoma (PC), but there was no palpable neck mass and no enlarged parathyroid glands were visualized on ultrasonography. Parathyroid scintigraphy was notable for faint but persistent Tc-99 m sestamibi uptake in the left inferior neck. Additional preoperative evaluation revealed significantly reduced bone mineral density in the distal third of the radius (0.638 g/cm2, Z-score -3.2), silent nephrolithiasis of the right kidney, and vitamin D deficiency (25-OH vitamin D 13.4 ng/dL, 30-100). An unequivocally enlarged (175 mg, 2.5 cm in largest diameter) left inferior parathyroid gland was removed, with the remaining glands unremarkable by inspection. Extensive nuclear atypia and cellular pleomorphism indicated an APA, and invasive features of PC were absent. One month after surgery, serum calcium improved to 10.2 mg/dL and intact PTH was 40 pg/mL. Conclusions APA account for 1-2% of PHPT cases. This patient's case has several features that distinguish it from a PA including degrees of preoperative hypercalcemia and intact PTH elevation, low vitamin D level, significantly reduced bone density in the distal third of the radius, nephrolithiasis, relatively young age, and male gender. Fibrous bands, pseudocapsular invasion, and trabecular growth pattern are the most common histologic features of APA, but nuclear atypia and cellular pleomorphism are well established diagnostic criteria. APA may be biochemically similar to PC but are distinguished from PC by the absence of gross invasion into adjacent anatomic structures, distant metastases, and vascular or perineural invasion. Additionally, CDC73 mutations are present in nearly all cases of PC but not in APA. Over 90% of patients with APA are successfully treated by parathyroidectomy. Careful follow up of APA patients is recommended, though there are no specific guidelines regarding a minimum satisfactory duration of postsurgical monitoring. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

S5.3d How mitochondrial complex I proteins in Candida albicans moderate phagocytosis and the production of pro-inflammatory cytokines in murine macrophages and dendritic cells

S5.3 Cellular pleomorphism and fungal virulence, September 22, 2022, 3:00 PM - 4:30 PM ObjectivesInhibition of respiration in Candida albicans impairs its colonization in the host tissues and causes avirulence in a murine vascular candidiasis model. Accordingly, blockage of the mitochondrial electron transport chain (ETC) of C. albicans by respiratory inhibitors promotes phagocytosis by increasing exposure of glucan which could be due to the mannan reduction. In our model, we have reported that 85% mannan reduction in goa1Δ, a deletion mutant of an ETC Complex I (CI) regulator, oppositely decreased phagocytosis. To understand such a difference, we broaden our investigation with three CI respiratory subunit mutants, which are either fungal-specific (nuo1Δ and nuo2Δ) or broadly conserved subunits (ndh51Δ) for cell wall analysis and innate immune responses.MethodsWe characterized mutant cell wall defects in these mutants, then analyzed their respective survival in macrophages. Fungal internalization into macrophages was visualized under fluorescent microscopy and live-cell imaging and analyzed through flow cytometry analysis. Cytokine production in dendritic cells (DCs) infected by fungal cells was measured by xMAP technology and the transcriptional profiles of murine macrophages-infected by different mutants were compared.ResultsWe find that phosphopeptidomannan (PPM) reduction in goa1Δ and nuo1Δ and phospholipomannan (PLM) reduction in nuo2Δ correlate with massive inhibition of cytokine. PPM loss in nuo1Δ or goa1Δ fails to promote phagocytosis but promotes opsonized neutrophil killing. The cause of PPM insufficiency results from reduced phosphorylation of the Cek1 MAPK in goa1Δ and nuo1Δ. In contrast other three mutants, phagocytosis and cytokine production of ndh51Δ more resemble WT cells, which have shown an ∼ 30% glucan reduction due to a defective Mek1 MAPK response. The divergent immune responses to these CI mutants are shown at the transcriptional level in infected macrophages. We noted that those well-characterized host receptors such as dectins and TLR2/4 for PPM, PLM, and glucan ligands are not significantly affected at 1 h post-infection. However, the scavenger receptor CD36, integrin ICAM, and growth factor receptors are downregulated along with a generally downregulated endocytosis and antigen processing/presentation. In addition, the host metabolic processes, oxidative stress-induced senescence, apoptosis, and signaling pathways such as Ras1/Erk5, the cAMP/CREB, and TLR9 pathway, are each individually affected in the host cells.ConclusionWe speculate that mitochondrial signals of fungal origin may also be sensed by the host immune cells to coordinate the immune responses together with cell replication and metabolism during the early stage of infection.

S5.3b Fungal spores: Initiators of colonization and infection

S5.3 Cellular pleomorphism and fungal virulence, September 22, 2022, 3:00 PM - 4:30 PMFungi produce asexual and sexual spores for reproduction and distribution, which can be both in space and time. Distribution in space occurs, by air movement, but also, by water or other vectors such as living organisms. Filamentous fungi from the division Ascomycota that belong to the order Eurotiales produce asexual spores called conidia. Conidia are moderately stress-tolerant cells and are able to survive unfavorable conditions such as thermal stress, dehydration, osmotic pressure, oxidative stress, variations in pH, and UV. For example, conidia of the fungus Penicillium chrysogenum are isolated worldwide and must be regarded as cosmopolitan. In many cases, conidia might ‘land’ closely to the location of production, but still many spores making into the higher air layers. There is indirect evidence that spores may be able to travel large distances through the air. For example, Aspergillus sydowii conidia have been suggested to travel over thousands of kilometers from the Sahara Desert to the Caribbean reefs. Distribution in time is occurring as stress-resistant cells remain dormant at one location for an extended period, awaiting conditions that are more favorable for growth. Some ascospores (sexual spores) are extremely stress-resistant and dormant for very long periods. Other species show extended dormancy in a dried state. As microbial species are inherently variable, stress resistance varies between strains from the same species. For example, conidial heat resistance (D60) of various strains of the fungus Paecilomyces variotii ranged between 3.5 to 27.6 min. This intraspecific variation could have profound consequences on diagnostics, virulence, and antifungal treatment in clinical settings. For conidial germination in most filamentous fungi, the presence of nutrients such as inorganic salts, sugars, and amino acids is required. The swelling phase of conidia is also called isotropic growth. Swollen conidia direct the growth to one side of the cell to grow in a polarized fashion, which leads to the formation of a germ tube (polarized growth). There is a notable drop in stress resistance during isotropic and polarized growth and genes expressed during these stages might represent novel targets for fungal infection.

S5.3c Investigating the link between pleomorphism and virulence in Cryptococcus

S5.3 Cellular pleomorphism and fungal virulence, September 22, 2022, 3:00 PM - 4:30 PMObjectivesFungal pathogens Cryptococcus neoformans and Cryptococcus gattii are responsible for hundreds of thousands of annual deaths in immunocompromised individuals. Considerable phenotypic variation is exhibited by strains in response to stresses encountered during host infection, including increased capsule and cell size, the release of shed capsule, and the production of giant (> 15 μm), micro (< 1 μm), and irregular cells. We aimed to investigate whether the production of these morphological variants is associated with virulence using two sets of strains. The first is a collection of diverse clinical isolates obtained from HIV/AIDS patients in Botswana with accompanying clinical data. The second is a collection of lineages derived from the C. neoformans type strain H99 with high genetic similarity but differing levels of virulence. Some lineages in this set possess a mutation in SGF29, which encodes a component of the SAGA histone acetylation complex that has previously been implicated in their hypervirulence.MethodsIsolates were cultured under conditions that simulate stresses encountered in vivo (DMEM, 5% CO2, 37°C) as these are known to enhance capsule production and induce cell size changes. Cells were counterstained with india ink, visualized by light microscopy, and phenotypes were scored. For clinical isolates, MLST analysis was performed to determine their relatedness. For H99 strains, Galleria mellonella larval infection assays, growth curves, and antifungal susceptibility testing was performed to confirm their relative virulence and growth profiles. Serial block face and regular scanning electron microscopy were used to investigate the internal morphology of the giant, micro, and irregular cells to confirm that they possess attributes of functional cells.ResultsSubstantial pleomorphism was seen across both collections. In the clinical strain set, phenotypic variables fell into two groups associated with differing symptoms. The production of ‘large’ phenotypes was associated with a higher CD4 count and was negatively correlated with intracranial pressure indicators, suggesting that these are induced in early-stage infection. ‘Small’ phenotypes were associated with lower CD4 counts, negatively correlated with meningeal inflammation indicators, and positively correlated with intracranial pressure indicators, suggesting that they are produced later during infection and may promote proliferation and dissemination. Isolates possessing giant cells, microcells, and shed capsules were rare, but strikingly, they were associated with patient death.In the H99 set, strains from hypervirulent lineages had larger average capsule size, greater variation in cell size, and increased production of microcells and shed capsules. Deletion of SGF29 in an intermediate virulence lineage substantially increased its production of microcells and released capsule, consistent with a switch to hypervirulence. SGF29 loss-of-function mutations were subsequently identified in clinical isolates and were found to be significantly correlated with patient death. Expansion of a TA repeat in the second intron of SGF29 in clinical isolates was positively correlated with cell and capsule size, suggesting it also affects Sgf29 function.ConclusionOur results extend the evidence for a link between pleomorphism and virulence, with a likely role for epigenetic mechanisms mediated by SAGA-induced histone acetylation.

S5.3a Unraveling the genetic determinants of virulence in Cryptococcus neoformans

S5.3 Cellular pleomorphism and fungal virulence, September 22, 2022, 3:00 PM - 4:30 PM Cryptococcus neoformans is a human pathogenic basidiomycete yeast that can cause cryptococcal meningitis (CM), predominantly in immunocompromised individuals. The patient outcome depends on both host and pathogen-specific factors, including C. neoformans genetics. A groundbreaking 2012 study was the first to show that patient outcome is associated with genetic differences between C. neoformans isolates. Subsequent population-wide sequencing studies have revealed over 100 sequence types (ST) of C. neoformans that are associated with both geographic location and clinical outcome. All these studies have been broad, examining the severity of disease cryptococcal phenotypes in a collection of highly diverse strains. We chose a narrow focus and collected various genotypic and phenotypic data from a single ST: ST93. ST93 is a common sequence type isolated from patients globally and is the most common clinical isolate found in the sub-Saharan African country of Uganda. Previously, we performed whole genome sequencing on 38 ST93 Ugandan clinical isolates. We identified 652 unique SNPs in this ST93 population compared to the H99 reference genome. We also showed that ST93 contained two subpopulations: ST9A and ST93B. In the current study, we further characterized the genotypic, phenotypic, and virulence differences between these 38 clinical isolates. Using Illumina sequence data, we identified a pattern of linkage disequilibrium that suggested that ST93A and ST93B are evolving separately. We performed long-read sequencing on each isolate to investigate chromosomal changes and large structural variations, allowing us to identify a chromosomal translocation event wherein parts of chromosome 11 had recombined with chromosome 3. Additionally, we characterized several in vitro phenotypes for each isolate and identified three distinct phenotypic clusters based on cell wall challenge and growth experiments. Next, we infected mice with 35 isolates and observed eight different disease manifestations, including isolates that caused non-CNS infections. Overall, by working within a single sequence type, we can gain a deeper understanding of how some small genetic changes can impact strain-specific phenotypes while others have no discernable effect. Eventually, these data can be used to provide valuable information about how each clinical isolate impacts patient outcomes.

SPINDLE CELL CARCINOMA: CASE REPORT

Spindle cell carcinoma (SCC) consists of biphasic, malignant, and rare neoplasm, with a poor prognosis due to the high probability of metastasis and recurrence. A 55-year-old White male patient, a drinker and smoker, presented with a mass on his tongue with a 6-month evolution that caused a burning sensation. Clinically, an exophytic, ulcerated, and hemorrhagic nodular lesion was observed in the left lateral edge of the tongue with the hypothesis of squamous cell carcinoma. An incisional biopsy was performed, allowing the diagnosis of SCC, a variant of squamous cell carcinoma, due to fusiform cells with atypia and cellular pleomorphism. Surgical excision was performed as treatment, but the patient died prior to the start of chemotherapy and radiotherapy.

SARCOMATOID CARCINOMA: A CASE REPORT

Sarcomatoid carcinoma (SC) is an infrequent variant of squamous cell carcinoma. A 62-year-old male patient with a long smoking and drinking history reported difficulty swallowing due to a rapidly growing mass in the floor of the mouth for 5 weeks. Intraorally, an exophytic mass of 2 cm was observed. After biopsy, histopathologic examination revealed a proliferation of neoplastic cells with epithelial differentiation, organized in nests and islands, as well as fascicles of spindle cells, exhibiting intense cellular pleomorphism and the presence of numerous atypical mitoses. Neoplastic cells with epithelial morphology were positive for anti-AE1/AE3 antibody and the spindle cell component strongly positive for vimentin and alpha-SMA. The anti-Ki67 antibody showed 38% of positivity in the epithelial component and 22% in the spindle cell component. The diagnosis of SC was made. The patient underwent chemotherapy but died after 12 months of treatment. Sarcomatoid carcinoma (SC) is an infrequent variant of squamous cell carcinoma. A 62-year-old male patient with a long smoking and drinking history reported difficulty swallowing due to a rapidly growing mass in the floor of the mouth for 5 weeks. Intraorally, an exophytic mass of 2 cm was observed. After biopsy, histopathologic examination revealed a proliferation of neoplastic cells with epithelial differentiation, organized in nests and islands, as well as fascicles of spindle cells, exhibiting intense cellular pleomorphism and the presence of numerous atypical mitoses. Neoplastic cells with epithelial morphology were positive for anti-AE1/AE3 antibody and the spindle cell component strongly positive for vimentin and alpha-SMA. The anti-Ki67 antibody showed 38% of positivity in the epithelial component and 22% in the spindle cell component. The diagnosis of SC was made. The patient underwent chemotherapy but died after 12 months of treatment.

PLASMABLASTIC LYMPHOMA OF THE PALATE

Plasmablastic lymphoma (PBL) is a rare large B-cell lymphoma usually affecting the oral cavity of patients positive for human immunodeficiency virus (HIV). Association with Epstein-Barr virus has been reported. A 61-year-old male patient with HIV presented with an asymptomatic, diffuse, and poorly delimited swelling on the left hard palate, covered by healthy mucosa, with unknown time of onset. Extraoral examination revealed no alteration. Incisional biopsy was performed, and microscopic examination revealed a hematologic neoplasm characterized by proliferation of plasmocytes showing cellular pleomorphism and numerous mitotic figures. Areas with a “starry-sky” appearance were noted. Immunohistochemistry was positive for plasma cell, lambda, and MUM-1. Ki-67 revealed a high proliferative index. In situ hybridization revealed positivity for Epstein-Barr virus. Based on these findings, PBL was diagnosed. The patient was referred for treatment, which included surgery and chemotherapy, with good therapeutic response. Currently, radiotherapy is being performed. Plasmablastic lymphoma (PBL) is a rare large B-cell lymphoma usually affecting the oral cavity of patients positive for human immunodeficiency virus (HIV). Association with Epstein-Barr virus has been reported. A 61-year-old male patient with HIV presented with an asymptomatic, diffuse, and poorly delimited swelling on the left hard palate, covered by healthy mucosa, with unknown time of onset. Extraoral examination revealed no alteration. Incisional biopsy was performed, and microscopic examination revealed a hematologic neoplasm characterized by proliferation of plasmocytes showing cellular pleomorphism and numerous mitotic figures. Areas with a “starry-sky” appearance were noted. Immunohistochemistry was positive for plasma cell, lambda, and MUM-1. Ki-67 revealed a high proliferative index. In situ hybridization revealed positivity for Epstein-Barr virus. Based on these findings, PBL was diagnosed. The patient was referred for treatment, which included surgery and chemotherapy, with good therapeutic response. Currently, radiotherapy is being performed.

Consideration of diagnosing extremely well differentiated adenocarcinoma of gastrointestinal tract

For gastrointestinal adenocarcinoma with excellent differentiation, some diagnostic names have emerged in recent years, which have overlapping and different meanings. Low-grade well differentiated adenocarcinoma and very well differentiated adenocarcinoma are terms for a group of adenocarcinomas with good differentiation and little cellular atypia, including a variety of histological types. It is suggested that specific histological types should be listed as far as possible in diagnosis, instead of using "low-grade well differentiated adenocarcinoma" or "very well differentiated adenocarcinoma" as a complete diagnosis. This kind of adenocarcinomas may lack cellular pleomorphism, so it is necessary to observe the structural atypia for diagnosis. At the same time, attention should be paid to the differentiation of reactive changes, low grade dysplasia, epithelial misplacement and other lesions.

Clinicopathological features of polymorphous low-grade neuroepithelial tumor of the young

Objective: To investigate the clinicopathological features and differential diagnosis of polymorphous low-grade neuroepithelial tumor of the young (PLNTY). Methods: Five cases of PLNTY diagnosed at the First Affiliated Hospital and Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China from 2019 to 2021 were collected. All cases were evaluated using clinical and imaging data, histology, immunohistochemical staining and molecular genetics. The relevant literature was reviewed. Results: There were two male and three female patients, aged 10 to 39 years, with an average age of 25 years. Clinically, the tumors were in the temporal lobe (3 cases), the lateral ventricle (1 case) and the left head of caudate nucleus (1 case). The clinical manifestations included epilepsy in 3 cases, right visual disturbance in 1 case, and post-trauma incidental finding in 1 case. Microscopically, the lesions were characterized with infiltrative growth, cellular pleomorphism (oligodendroglioma-like cells were always present, with low-grade, pleomorphic nuclei) and variable calcifications. Immunohistochemically, the tumor cells were positive for GFAP and Olig2. They also showed intense and diffuse expression of CD34 while CD34 expressing ramified neural elements were present in regional cortex. Ki-67 proliferation index was less than 3%. Molecular genetics showed the BRAF V600E mutation in 2 cases, the PAK5-Q337R missense mutation in 1 case, the FGFR2-CTNNA3 fusion in 1 case, and the FGFR2-INA and FGFR2-PPRC1 concomitant fusion in 1 case. No postoperative chemoradiotherapy was given. Follow-up intervals ranged from 3 to 29 months while no recurrence or metastasis was identified. Conclusions: PLNTY is uncommon. A definite diagnosis of PLNTY relies on histopathological examination and molecular genetics. It is important to distinguish PLNTY from high grade gliomas and avoid overtreatment. The recently reported the PAK5-Q337R missense mutation and the FGFR2-PPRC1 gene fusion in PLNTY may help diagnose and understand the pathogenesis of PLNTY.

Desmoplastic infantile astrocytoma with atypical phenotype, PTEN homozygous deletion and BRAF V600E mutation

Desmoplastic infantile astrocytoma (DIA) is rare, cystic and solid tumor of infants usually found in superficial cerebral hemispheres. Although DIA is usually benign, uncommon cases bearing malignant histological and aggressive clinical features have been described in the literature. We report a newborn patient who was diagnosed with a DIA and died postresection. Pathologic examination revealed that the main part of the tumor had benign features, but the internal region showed areas with a more aggressive appearance, with higher-proliferative cells, anaplastic GFAP positive cells with cellular polymorphism, necrosis foci, vascular hyperplasia with endothelial proliferation and microtrombosis. Genetic study, performed in both regions of the tumor, showed a BRAF V600E mutation and a homozygous deletion in PTEN, without changes in other relevant genes like EGFR, CDKN2A, TP53, NFKBIA, CDK4, MDM2 and PDGFRA. Although PTEN homozygous deletions are described in gliomas, the present case constitutes the first report of a PTEN mutation in a DIA, and this genetic feature may be related to the malignant behavior of a usually benign tumor. These genetic findings may point at the need of further and deeper genetic characterization of DIAs, in order to better understand the biology of this tumor and to obtain new prognostic approaches, a better clinical management and targeted therapies, especially in malignant cases of DIA.

Abstract 5948: Modeling lung squamous cell carcinoma progression using primary human bronchial basal cells

Abstract Background: Lung squamous cell carcinoma (LUSC) arises from the accumulation of genetic driver alterations in bronchial basal cells. LUSC genomes lack obvious actionable mutations and present with a high degree of inter-tumor heterogeneity. Tractable, patient relevant models are needed to study LUSC pathogenesis and investigate the role of recurrent genomic alterations in driving cancer progression. Therefore, we are developing a tractable human model of LUSC progression to increase our understanding of this disease. Methods: To investigate the contribution and co-operation of frequently mutated genes (TP53 and CDKN2A) and commonly deregulated pathways (SOX2/P63, PI3K/AKT and KEAP1/NRF2 pathways) in driving LUSC progression, we genetically engineered primary human bronchial basal cells. This culminated in eight basal cell mutants harboring ubiquitous LOF alterations in TP53 and CDKN2A combined with additional pathway alterations. To assess the function of the genetic alterations in LUSC progression, we investigated proliferation using cell cycle analysis and colony forming assays. Air-liquid interface organotypic cultures were used to model histological changes in the bronchial epithelium driven by different combinations of mutations. The resultant cultures were analyzed for changes in histology indicative of LUSC progression using immunostaining to evaluate changes to epithelial cell proliferation, and expression of LUSC biomarkers. Results: Increases in proliferation were driven by inactivation of TP53, CDKN2A and PTEN, whereas SOX2 overexpression inhibited mutant basal cell proliferation. LUSC alterations also drove striking phenotypic changes in 3D organotypic cultures of the bronchial epithelium. All mutant cultures displayed thickening of the bronchial epithelium and significantly increased cellularity (p&amp;lt;0.001), indicating hyper-proliferation. SOX2 overexpression inhibited mucociliary differentiation and drove the appearance of a disordered epithelium with clear cellular and nuclear pleomorphism, indicative of high-grade premalignant lesions. Conclusions: We developed a basal cell model of recurrent LUSC genetic alterations. This approach is unique due to [1] the use of primary human cells and [2] the representation of interpatient heterogeneity and developmental stages by introducing different combinations of pathway alterations. Early results indicate that basal cells carrying cumulative alterations display increasingly complex phenotypes with features of low and high-grade premalignant lesions. Further work is required to assess the tumorigenicity of mutant cells. Citation Format: Julia Ogden, Caroline Dive, Carlos Lopez Garcia. Modeling lung squamous cell carcinoma progression using primary human bronchial basal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5948.