Abundant Cytoplasm Research Articles

Low-grade papillary Schneiderian carcinoma with TP53 mutation: a case report and review of the literature

BackgroundLow-grade papillary Schneiderian carcinoma (LGPSC) is a relatively new entity of the sinonasal tract and is characterized by a bland morphology simulating sinonasal papilloma, invasive growth pattern with pushing borders, and aggressive clinical behavior with multiple recurrences and metastatic potential. Recently, DEK::AFF2 fusions were identified in LGPSC. However, some LPGSCs lack DEK::AFF2 fusion, and the molecular features of these tumors have not been clarified.Case presentationA 69-year-old man presented with a discharge of pus from his left cheek. Computed tomography revealed a mass involving the left maxillary sinus, ethmoid sinus, and nasal cavity with the destruction of the orbital wall. The biopsy specimens showed that the tumor had a predominantly exophytic, papillary growth and did not have an apparent stromal invasion. The tumor was composed of multilayered epithelium that showed bland morphology with a round to polygonal shape, abundant eosinophilic cytoplasm, and uniform nuclei. Dense neutrophilic infiltrates were focally present. Immunohistochemically, CK5/6 was strongly and diffusely positive, and p16 was negative. p63 was mainly positive in the basal layer, and EMA was predominantly expressed in the outermost cell layer. DNA-based targeted sequencing showed TP53 R175H mutation, whereas neither EGFR nor KRAS mutation was identified. Reverse transcription polymerase chain reaction and fluorescence in situ hybridization revealed no DEK::AFF2 fusion.ConclusionsWe describe the first case of TP53-mutant LGPSC and review the literature. LGPSC is a genetically heterogeneous entity, and the recognition of this rare entity and comprehensive assessment of clinicopathological and molecular findings are crucial for the correct pathological diagnosis and clinical management.

Papillary thyroid carcinoma with desmoid-type fibromatosis: the clinicopathological features with characteristic imaging and molecular correlation requiring comprehensive treatment

The pathogenesis and treatment of papillary thyroid cancer with desmoid-type fibromatosis (PTC-DTF), a rare subtype of papillary thyroid carcinoma characterized by a mixed epithelial-mesenchymal structure, are still ill-defined. Previous reports on PTC-DTF have had limited follow-up and recurrence has been rarely reported. To better understand this condition, we conducted a thorough analysis of five cases of PTC-DTF from our institute, including clinical and pathological examinations, imaging, immunohistochemistry, and molecular analysis. We also reviewed relevant literature. The mean age of the patients was 51.8 years, with three women and two men included in the group. Ultrasound often showed a hypoechogenic and well-defined nodule in the thyroid gland, except for one individual who had distant lung metastases detected by PET-CT. The nodules ranged in width from 0.5 to 5.0 cm and were excised in each case. Following surgery, 131I therapy was used in two cases. The overall number of PTC-DTF cases has risen from the previously reported 55 to 60, with females being the most commonly affected and ranging in age from 19 to 82. Most masses underwent a thyroidectomy, and approximately half of the patients had lymph node metastases. Histologically, PTC-DTFs were composed of a predominant stromal component (65% - 90%) and an intervening epithelial component. These spindle cells were arranged in parallel with abundant cytoplasm and vacuole-like nucleus but there wasn't evident atypia. The carcinoma cells were positively stained for CK and TTF-1 by immunohistochemistry, whereas mesenchymal cells were positive for SMA and displayed nuclear immunoreactivity for β-catenin. BRAF, NRAS, and CTNNB1 mutations were identified in the epithelial and mesenchymal components through molecular testing, respectively. Perhaps because the mesenchyme harbors aberrant nuclear β-catenin expression, PTC-DTF is more aggressive and prone to invasion and distant recurrence, as shown by our case 2, which is the first case to be reported thus far. PTC-DTF is typically treated with surgery, but clinicians may occasionally consider more holistic treatment plans that involve radioactive iodine and endocrine therapy.

Cephalochordate Hemocytes: First Demonstration for Asymmetron lucayanum (Bahamas Lancelet) Plus Augmented Description for Branchiostoma floridae (Florida Amphioxus).

AbstractWithin phylum Chordata, the subphylum Cephalochordata (amphioxus and lancelets) has figured large in considerations of the evolutionary origin of the vertebrates. To date, these discussions have been predominantly based on knowledge of a single cephalochordate genus (Branchiostoma), almost to the exclusion of the other two genera (Asymmetron and Epigonichthys). This uneven pattern is illustrated by cephalochordate hematology, until now known entirely from work done on Branchiostoma. The main part of the present study is to describe hemocytes in the dorsal aorta of a species of Asymmetron by serial block-face scanning electron microscopy. This technique, which demonstrates three-dimensional fine structure, showed that the hemocytes have a relatively uniform morphology characterized by an oval shape and scanty cytoplasm. Ancillary information is also included for Branchiostoma hemocytes, known from previous studies to have relatively abundant cytoplasm; our serial block-face scanning electron microscopy provides more comprehensive views of the highly variable shapes of these cells, which typically extend one or several pseudopodium-like protrusions. The marked difference in hemocyte morphology found between Asymmetron and Branchiostoma was unexpected and directs attention to investigating comparable cells in the genus Epigonichthys. A broader knowledge of the hemocytes in all three cephalochordate genera would provide more balanced insights into the evolution of vertebrate hematopoiesis.

Fine needle aspiration cytology of follicular dendritic cell sarcoma of the stomach masquerading as gastrointestinal stromal tumor: A case report of a unique entity with emphasis on cytomorphology.

Follicular dendritic cell sarcoma (FDCS) is a rare malignant neoplasm, postulated to arise from follicular dendritic cells, with approximately 343 reported cases. Less than 100 cases of FDCS were in the gastrointestinal tract, with only four cases described in the stomach, none of them diagnosed on fine needle aspiration (FNA) cytology. We report here the first case of FDCS of the stomach diagnosed on FNA. Our patient is a 31-year-old male who presented with several years history of intermittent abdominal pain prompting occasional emergency-room visits. Imaging showed a 10.6 cm mass arising from the stomach, concerning for gastrointestinal stromal tumor. FNA cytology was performed using five passes with a 22-gauge needle. The smears were moderately cellular consisting of sheets and large, loosely cohesive clusters of ovoid to spindle cells with indistinct cytoplasmic borders and abundant cytoplasm, peppered with numerous small mature lymphocytes. The nuclei of the tumor cells were oval with finely granular chromatin with frequent nuclear grooves, pseudoinclusions, and easily recognizable mitotic figures. The tumor cells were positive for FDCS markers (CD21, CD23, and CD35).

Urothelial carcinoma in situ with “overriding” features can evade detection by mimicking umbrella cells

Urothelial carcinoma in situ (uCIS) is typically recognized by overtly malignant cells with characteristic nuclear features; multiple histologic patterns have been described. A rare "overriding" pattern, in which uCIS tumor cells extend on top of normal urothelium, has previously been mentioned in the literature, but not well described. Herein, we report 3 cases of uCIS with "overriding" features. Detailed morphologic evaluation revealed somewhat subtle cytologic atypia: variably enlarged hyperchromatic nuclei and scattered mitotic figures but with abundant cytoplasmand limited to superficial urothelium. Immunohistochemical (IHC) analysis showed a distinctive diffuse positive aberrant p53 pattern, limited to the atypical surface urothelial cells; these cells also showed CK20+, CD44-, and increased Ki-67. In 2 cases, there was a history of urothelial carcinoma and adjacent conventional uCIS. In the third case, the "overriding" pattern was the first presentation of urothelial carcinoma; therefore, next-generation sequencing molecular testing was also performed, revealing pathogenic mutations in TERTp, TP53, and CDKN1a to further support neoplasia. Notably, the "overriding" pattern mimicked umbrella cells, which normally line surface urothelium, can have abundant cytoplasm and more variation in nuclear and cell size and shape, and show CK20+ IHC. We therefore also evaluated umbrella cell IHC patterns in adjacent benign/reactive urothelium, which showed CK20+, CD44-, p53 wild-type, and very low Ki-67 (3/3). We also reviewed 32 cases of normal/reactive urothelium: all showed p53 wild-type IHC in the umbrella cell layer (32/32). In conclusion, caution is warranted to avoid overdiagnosis of usual umbrella cells as CIS; however, "overriding" uCIS should be recognized, may have morphologic features that fall short of the diagnostic threshold of conventional CIS, and requires further study.

Epithelioid inflammatory myofibroblastic sarcoma: a pitfall in the differential diagnosis of ALK-positive anaplastic large cell lymphoma.

An 18-year-old female presented with a 4.5 cm abdominal mass. Biopsy showed sheet-like growth of large tumor cells with round to oval nuclei, 1-2 nucleoli, and abundant cytoplasm. Immunohistochemistry showed strong, uniform CD30 staining and cytoplasmic ALK staining. B-cell markers (CD20, CD79a, PAX5, kappa/lambda) and T-cell markers (CD2, CD3, CD4, CD5, CD43, granzyme B, T-cell receptor-β) were negative. Other hematopoietic markers (CD45, CD34, CD117, CD56, CD163, EBV) were negative, but CD138 was positive. Non-hematopoietic markers showed desmin positivity and negativity for S100, melan A, HBM45, PAX8, PAX2, WT1, MYO-D1, myogenin, pancytokeratin, and CAM5.2. Sequencing identified PRRC2B::ALK fusion. A diagnosis of epithelioid inflammatory myofibroblastic sarcoma (EIMS) was made. EIMS is a rare, aggressive form of inflammatory myofibroblastic tumor typically presenting in children and young adults. The tumor comprises large epithelioid cells that express ALK and often CD30. ALK-positive ALCL has a similar age range and also is a large-cell tumor expressing CD30 and ALK. Other ALK-positive neoplasms (e.g., carcinomas, ALK-positive large B-cell lymphoma, ALK-positive histiocytosis) typically lack CD30 and have distinct clinicopathologic features that aid diagnosis. Hematopathologists need to distinguish EIMS from ALK-positive ALCL, which frequently shows loss of pan-T-cell antigens. Careful morphologic evaluation for the hallmark cells of ALCL and comprehensive phenotyping are critical to avoid this diagnostic pitfall. If known, the ALK rearrangement partner gene may also provide diagnostic clues; for example PRRC2B::ALK and RANBP2::ALK occur in EIMS but not ALCL.

Multisystem ALK-positive histiocytosis: a multi-case study and literature review

BackgroundAnaplastic lymphoma kinase (ALK)-positive histiocytosis, a novel rare histiocytic proliferation, was first described in 2008; it occurs in early infancy with liver and hematopoietic involvement. The spectrum was subsequently broadened to include localized diseases in older children and young adults. However, its full clinicopathological features and molecular lineage have not been fully elucidated.ResultsHere, we report four cases of multisystem ALK-positive histiocytosis without hematopoietic involvement. Clinically, three patients were adults aged between 32 and 51 years. Two patients’, whose main manifestations were intracranial mass and numerous micronodules in the thoracoabdominal cavity organs and skin papules respectively, had a partial response to ALK inhibitors after surgery. One patient presented with mediastinal neoplasm without surgical treatment, and progressive disease occurred after two years of ALK inhibitor therapy. The fourth patient was a 17-month-old male with a large intracranial mass and presented with a poor response to ALK inhibitor and chemoradiotherapy; he died eight months after surgery. Pathologically, the histiocytes were large, with abundant eosinophilic cytoplasm, and mixed with variable numbers of foamy cells and Touton giant cells. Interstitial fibrosis was also observed. Histiocytes were positive for macrophage markers (CD68 and CD163) and ALK. KIF5B-ALK fusions were detected in two cases, EML4-ALK in one, and both DCTN1-ALK and VRK2-ALK fusions were detected in one case.ConclusionsWe observed that ALK inhibitors present robust and durable responses in adult patients but a poor response in young children with central nervous system involvement. There is no consensus on the optimal treatment regimen and long-term prognosis requires further observation. Moreover, every unusual histiocytic proliferative lesion, especially unresectable and multisystem involvement, should be routinely tested for ALK immunohistochemical staining to identify this rare disease.

Secondary Breast Malignancy from Renal Cell Carcinoma: Challenges in Diagnosis and Treatment—Case Report

Renal cell carcinoma represents about 2% of all malignant tumours in adults. Metastases of the primary tumour in the breast make up to about 0.5-2% of the cases. Renal cell carcinoma metastases in the breast are extremely rare and have been sporadically recorded in the literature. In this paper, we present the case of a patient with breast metastasis of renal cell carcinoma 11 years after primary treatment. Case presentation: An 82-year-old female who had right nephrectomy due to renal cancer in 2010 felt a lump in her right breast in August 2021, whereby a clinical examination revealed a tumour at the junction of the upper quadrants of her right breast, about 2 cm, movable toward the base, vaguely limited, and with a rough surface. The axillae were without palpable lymph nodes. Mammography showed a circular and relatively clearly contoured lesion in the right breast. Ultrasound showed an oval lobulated lesion of 19 × 18 mm at the upper quadrants, with strong vascularisation and without posterior acoustic phenomena. A core needle biopsy was performed, and the histopathological findings and obtained immunophenotype indicated a metastatic clear cell carcinoma of renal origin. A metastasectomy was performed. Histopathologically, the tumour was without desmoplastic stroma, comprising predominantly solid-type alveolar arrangements of large moderately polymorphic cells, bright and abundant cytoplasm, and round vesicular cores with focally prominent nuclei. Immunohistochemically, tumour cells were diffusely positive for CD10, EMA, and vimentin, and negative for CK7, TTF-1, renal cell antigen, and E-cadherin. With a normal postoperative course, the patient was discharged on the third postoperative day. After 17 months, there were no new signs of the underlying disease spreading at regular follow-ups. Conclusion: Metastatic involvement of the breast is relatively rare and should be suspected in patients with a prior history of other cancers. Core needle biopsy and pathohistological analysis are required for the diagnosis of breast tumours.

Une lésion labiale inhabituelle

A 75 years old patient presented with a papular easily bleeding lesion of the lower lip that had been growing for two months. He was known for alcoholic cirrhosis complicated with hepatocellular carcinoma treated since one year. A working diagnostic hypothesis of benign vascular lesion was proposed. Microscopic examination showed a neoplastic dermal proliferation that had been fully excised, made of lobules segregated by thin fibrous septae. The neoplastic architecture was trabecular and delineating spaces forming pseudo-rosettes. Tumour cells were monomorphic, cuboidal or cylindric with abundant eosinophilic and granulous cytoplasm and centered by a lone nucleus that often contained a prominent nucleolus. Some spaces were filled with a brownish-greenish pigmented material. Immunohistochemical study showed that tumour cells were positive with the hepatocyte paraffin 1 antibody as well as cytokeratin 8 antibody. Chromogranin A and synaptophysin stainings were negative. Thus we concluded to a lip metastasis from the previously known hepatocellular carcinoma. Skin metastasis arise in around 3% of cases of hepatocellular carcinoma. They account for less than 1% of all cutaneous metastasis. Overall appearance of cutaneous metastasis of hepatocellular carcinoma is associated with a poor prognosis and an aggravated risk of metastasis to other locations and organs and a median overall survival of less than 5months. Since incidence of hepatocellular carcinoma is rising pathologists might face more frequently in years to come to cutaneous metastasis whose varied clinical presentations make a diagnostic challenge.

Clinicopathological study of pseudomyogenic hemangioendothelioma

ObjectivesPseudomyogenic hemangioendothelioma (PHE) is a rare intermediate hemangioendothelioma. This article aims to study the clinicopathological features of PHE.MethodsWe collected the clinicopathological features of 10 new PHE, and examined their molecular pathological features by fluorescence in situ hybridization. In addition, we summarized and analyzed the pathological data of 189 reported cases.ResultsThe case group consisted of six men and four women aged 12–83 years (median: 41 years). Five instances occurred in the limbs, three in the head and neck, and two in the trunk. Tumor tissues were composed of spindle cells and round or polygonal epithelioid cells, which were either arranged in sheets or interwoven, along with areas of transitional morphology. Scattered or patchy stromal neutrophil infiltration was observed. Tumor cells had abundant cytoplasm, and some contained vacuoles. The nuclei had mild to moderate atypia, with visible nucleoli, and mitosis was rare. PHE tissues diffusely expressed CD31 and ERG, but not CD34, Desmin, SOX-10, HHV8 or S100, while some samples expressed CKpan, FLI-1 and EMA. INI-1 stain is retained. The proliferation index of Ki-67 is 10–35%. Seven samples were detected by fluorescence in situ hybridization, six of which had breakages in FosB proto-oncogene (AP-1 transcription factor subunit). Two patients experienced recurrence; however, no metastasis or death occurred.ConclusionsPHE is a rare soft tissue vascular tumor, which has biologically borderline malignant potential, local recurrence, little metastasis, and good overall survival and prognosis. Immunomarkers and molecular detection are valuable for diagnosis.

Pulmonary granular cell tumors: a clinicopathological analysis of five cases

Objective: To investigate the clinicopathological features of pulmonary granular cell tumors (pGCTs) and to improve the diagnostic accuracy of the tumor. Methods: A total of 5 pGCTs were diagnosed from February 2016 to January 2022 at Shanghai Pulmonary Hospital, Tongji University School of Medicine and Fudan University Shanghai Cancer Center, China. Immunohistochemical staining, and analysis of the clinicopathological characteristics were performed. Results: The average age of the pGCTs patients was 46 years (ranging from 24 to 54 years), with 3 females and 2 males. One case occurred in the bronchus with multiple nodules in the lung, 2 cases occurred in the bronchial opening, and 2 cases were solitary nodules in the lung. The maximum diameter of the tumors ranged from 12 to 15 mm (mean size 14 mm). Microscopically, the tumor showed infiltrative growth and consisted of round, oval or polygonal cells. Abundant eosinophilic cytoplasm was noted, and the nucleoli were prominent. None of the 5 cases showed any mitosis or necrosis. Immunohistochemical and histochemical study showed positive staining for S-100 (5/5), SOX10 (5/5), Vimentin (5/5), TFE3 (4/5), PAS (3/5), and amylase-digested-PAS (3/5), while 4 cases were negative for CD68. TFE3 FISH analyses on 2 cases showed that no signal abnormality was detected in these 2 cases. The average proliferation index of Ki-67 was 2.2% (range 0-5%). There was no recurrence in 4 cases of pGCTs with a follow-up time ranging from 2 months to 60 months. Conclusions: pGCTs are very rare tumors, most likely originating from Schwann cells. Immunohistochemical staining is the conventional diagnostic tool for pGCTs diagnosis. Recognition of this entity is essential for pathologists to avoid misdiagnosis and unnecessary treatments.

Dedifferentiated leiomyosarcoma of the uterus: a clinicopathologic and immunohistochemical analysis of 23cases.

To morphologically and immunophenotypically characterize dedifferentiated uterine leiomyosarcoma (LMS). We identified 23 dedifferentiated uterine LMS, defined as a malignant uterine smooth muscle tumour containing discrete differentiated and dedifferentiated components (i.e. with and without morphologic and immunophenotypic evidence of smooth muscle differentiation, respectively). The differentiated component was leiomyosarcoma in most cases (17/23), though some arose from a leiomyoma (n=4) or smooth muscle tumour of uncertain malignant potential (n=2). The dedifferentiated tumour component showed noncohesive polygonal cells with moderate to abundant cytoplasm, pleomorphic nuclei with coarse vesicular to smudged chromatin, one or more macronucleoli, frequent multinucleation,and atypicalmitoses. Three cases showed heterologous osteosarcomatous or chondrosarcomatous differentiation. Immunohistochemistry revealed alterations characteristic of uterine LMS, including Rb loss (18/19); strong diffuse p16 (17/19); strong diffuse (9/19) or complete absence of (5/19) p53; and ATRX loss (6/16). Compared to a control cohort of uterine LMS without dedifferentiation, dedifferentiated uterine LMS showed significantly shorter disease-specific (median, 54 versus 20months; 5-year DSS, 46% versus 36%; P=0.04) and disease-free (median, 31 versus 8 months; 5-year DFS, 42% versus 8%; P=0.002) survival. Of 19 dedifferentiated uterine LMS with follow-up, 12 had died of disease at median 14 (range, 2-73)months; four were alive with disease at 4, 12, 44, and 50months; and three were alive with no evidence of disease at 56, 109, and 114months. Routine prospective recognition of dedifferentiated uterine LMS and distinction from mimics is advocated for accurate prognostication and for further characterisation of these tumours.

The Presence of Typical "BRAFV600E-Like" Atypia in Papillary Thyroid Carcinoma is Highly Specific for the Presence of the BRAFV600E Mutation.

Papillary thyroid carcinomas (PTCs) are driven by a variety of molecular abnormalities including BRAF, RAS, ALK, RET, and NTRK alterations. PTCs driven by the BRAFV600E mutation, or tumours which demonstrate a similar gene expression profile to PTCs driven by this mutation, have been reported to demonstrate specific morphological features sometimes termed "BRAFV600E-like" atypia. BRAFV600E-like atypia is characterised by a well-developed papillary architecture, infiltrative growth, marked nuclear clearing, prominent intranuclear pseudoinclusions, abundant eosinophilic cytoplasm, and scattered psammoma bodies. We sought to investigate the sensitivity and specificity of these morphological features for the presence of BRAFV600E mutation in PTCs as determined by mutation specific immunohistochemistry. An unselected cohort of 495 PTCs was reviewed by a single pathologist and categorised into three groups: typical BRAFV600E-like atypia (145 cases, 29%), possible BRAFV600E-like atypia (166 cases, 33%) and little/no BRAFV600E-like atypia (184 cases, 37%). The specificity and sensitivity of typical BRAFV600E-like atypia for the BRAFV600E mutation was 97.2% and 44.3%, respectively. When typical and possible BRAFV600E-like atypia were analysed together, the specificity was 70.6% and the sensitivity was 81.7%. In the morphologically little/no BRAFV600E-like atypia group, 58 cases (31.5%) had a BRAFV600E mutation. We conclude that typical BRAFV600E-like atypia is highly specific for the presence of the BRAFV600E mutation; however, the absence of BRAFV600E-like atypia does not exclude this mutation.

THE UNFORTUNATE PERFECT STORM - SEPTIC SHOCK DUE TO CHRONIC IMMUNOSUPPRESIVE MEDICAL THERAPY AND MEDICATION-INDUCED LYMPHOMA

Abstract INTRODUCTION Pharmacological treatment of Crohn's Disease (CD) involves immunomodulators such as adalimumab, a tumor necrosis factor (TNF) inhibitor and azathioprine, a purine analogue. These medications have risks associated with severe illness from infectious etiologies as well as lymphoma development. This is due to the immunosuppressive effect of the medications as well as a chronic inflammatory state(1). Anaplastic large-cell lymphoma (ALCL) is a subtype of non-Hodgkin's lymphoma (NHL). We present a rare case of sepsis and ALCL in a patient on immunomodulator therapy. CASE DESCRIPTION A 31-year-old G1P0 female at 19 weeks gestation with history of Crohn’s disease presents with abdominal pain. Her medications are adalimumab and azathioprine which were started one year ago due to poorly controlled CD resulting in anal fistulas. She was recently treated for right thigh folliculitis. This progressed to abdominal pain and right inguinal lymphadenopathy. She met SIRS criteria on presentation and was admitted to the intensive care unit for respiratory failure requiring intubation. Despite broad-spectrum antibiotics for pneumonia, she remained febrile with an increasing leukocytosis. Blood, lower respiratory, and fungal cultures, acid-fast staining, viral cultures and smears, and urine tests were negative for a source of infection. Commuted tomography (CT) of the abdomen and pelvis was significant for extensive retroperitoneal lymphadenopathy but found no infectious source. An excisional biopsy of the right groin lymph node was a preliminary read as Hodgkin's lymphoma (HL), but the initial immunohistochemical stain was consistent with NHL. Her immunomodulator therapy was stopped due to sepsis and her risk of lymphoma. She subsequently developed septic shock, acute renal failure requiring continuous renal replacement therapy, atrial fibrillation with rapid ventricular response, and suffered a spontaneous vaginal delivery of a 20-week stillborn baby. A final diagnosis of ALCL was confirmed by pathology. The molecular studies were significant for positivity for CD45, CD30, EMA, CD2, CD4, CD25, ALK1, granzyme B, perforin, and TIA1. She was started on brentuximab, cyclophosphamide, and prednisone. DISCUSSION ALCL is a rare subtype of NHL that accounts for roughly one percent of all NHL (3). The development of lymphomas occurs when the TNF alpha subunit binds to the cell surface. This inhibits both the apoptosis pathway and cytokine-mediated inhibition of CD30+ lymphoma cells resulting in cell proliferation (4). There is limited documentation of adalimumab or azathioprine associated ALCL and this association should be studied further. The patient suffered from severe consequences of her immunosuppression from her chronic immunomodulator therapy and immunosuppression from her malignancy resulting in septic shock with multiorgan failure. Right inguinal lymph node biopsy showing atypical large lymphoid infiltrate, background small lymphocytes, plasma cells, and histiocytes. The large atypical cells are characterized by large irregular nuclei with occasional bilobed nuclei and horseshoe-shaped nuclei, multiple small nucleoli, and abundant amphophilic cytoplasm.

Primary splenic diffuse large B-cell lymphoma presenting as a splenic abscess.

Diffuse large B-cell lymphoma (DLBCL) arising in the spleen, also known as primary splenic DLBCL (PS-DLBCL), is a rare form of malignant lymphoma. It is defined as a lymphoma confined to the spleen or involving splenic hilar lymph nodes. Here we report a case of PS-DLBCL with CD30. The patient was a 62-year-old who presented with 2 weeks of left flank pain, chills, and abdominal distension. Computed tomography identified an 8-cm splenic mass with central necrosis interpreted as an abscess. A drain was placed, yielding purulent necrotic material; cytologically, only neutrophils were identified. However, purulent drainage continued for 28 days without resolution, prompting splenectomy. Pathological dissection revealed a multinodular mass with central necrosis. Microscopic examination revealed extensive karyorrhexis, abundant ghosts of large cells, and scattered large cells with pleomorphic, multilobated, and vesicular nuclei with moderately abundant cytoplasm. Immunohistochemical staining revealed large, atypical cells positive for CD20, CD30, CD45, PAX5, MYC (>40%), MUM1 (>30%), and p53 (focally). The large cells were negative for CD3 (polyclonal), CD4, CD5, CD8, CD10, CD15, CD34, BCL2, BCL6, AE1/AE3, S100, HHV8, and ALK. The Ki-67 proliferation rate was approximately 80% in large cells. Notably, this PS-DLBCL was positive for CD30, an unusual finding among non-Hodgkin B-cell lymphomas, which, coupled with the Reed-Sternberg-like morphology, raised the possibility of classic Hodgkin lymphoma. Therefore, we reviewed the literature to confirm the unique features of this large B-cell lymphoma, its abscess-like appearance, and its expression of CD30.

Interobserver Reproducibility in Assessing Eosinophilic Cells in Ovarian Serous Borderline Tumors to Predict BRAF Mutational Status.

Ovarian serous borderline tumors (SBTs) harboring the BRAFV600E mutation are associated with decreased risk of progression to low-grade serous carcinoma, and often prominently feature tumor cells with abundant eosinophilic cytoplasm. Since eosinophilic cells (ECs) may be a marker of the underlying genetic driver, we proposed morphologic criteria and evaluated the interobserver reproducibility for assessing this histologic feature. Following the completion of an online training module, representative tumor slides from 40 SBTs ( BRAFV600E -mutated, n=18, BRAF -wildtype, n=22) were independently reviewed by 5 pathologists. For each case, reviewers provided a semiquantitative assessment of the extent of ECs (0: absent, 1: <10%, 2: 10%-50%, or 3: >50%, of tumor area). Interobserver reproducibility for estimating the extent of ECs was moderate (κ=0.41). Applying a cut-off score of ≥2, the median sensitivity and specificity for predicting BRAFV600E mutation were 67% and 95%, respectively. With a cut-off score of ≥1, median sensitivity and specificity were 100% and 82%, respectively. Morphologic mimics of ECs, including tumor cells with tufting or hobnail change and detached cell clusters in micropapillary SBTs, were possible contributing factors for discordant interobserver interpretations. BRAFV600E immunohistochemistry showed diffuse staining in BRAF -mutated tumors, including those with few ECs. In conclusion, the finding of extensive ECs in SBT is highly specific for BRAFV600E mutation. However, in some BRAF -mutated SBTs, ECs may be focal and/or difficult to distinguish from other tumor cells with overlapping cytologic features. The morphologic finding of definitive ECs, even when scarce, should therefore prompt consideration for BRAFV 600E mutation testing.

Perivascular epithelioid cell tumor of the uterine cervix identified on the liquid-based cytology: a case report

BackgroundPerivascular epithelioid cell tumor (PEComa) occurring in the female genital tract are rare, and typically found in the uterine corpus. PEComa occurring in the cervix is extremely rare, and very few cases have been reported till now. Cytological diagnosis of cervical PEComa is even rarer. So far, only two cases of PEComa diagnosed by conventional cervical smears have been reported.Case presentationA 55-year-old postmenopausal woman presented with abnormal vagina discharge for 3 months. A liquid-based cytology test was performed. Microscopically, some loosely cohesive epithelioid cells were uniform with abundant clear cytoplasm, showing predominantly round or oval nuclei with finely stippled chromatin. Distinct round nucleoli were visible in some cells, notably with numerous melanin pigments in the cytoplasm. The cytopathological features were well correlated with cell block and histopathological findings. Upon immunohistochemistry (IHC), the tumor cells were positive for HMB45 and TFE3, focally positive for MelanA, while negative for muscle marker. Fluorescence in situ hybridization (FISH) confirmed TFE3 gene rearrangement. The final pathological diagnosis was PEComa identified by the liquid-based cytology, cell block, cervical biopsy, IHC and FISH result. The patient underwent a total hysterectomy with bilateral salpingo-oophorectomy and was followed up for 2 years with no evidence of disease.ConclusionThe cytologic characteristics of the tumor can provide sufficient clues for PEComa diagnosis, which includes loosely cohesive, epithelioid morphology with abundant clear or eosinophilic cytoplasm, low-grade nuclear atypia, cytoplasmic melanin pigments. This will help cytopathologists to recognize this rare tumor that occurred in the cervix, and the combination of predictive morphology evaluation, immunophenotype, and molecular testing can achieve the definitive diagnosis of PEComa.

Hibernoma-A rare tumor on rare site

Hibernoma is a rare benign tumor that originates from brown fat. Hibernoma is thought to arise from areas containing residual brown fat like- the interscapular area, axilla, neck, chest, abdominal cavity, and retroperitoneum. The incidence of this rare tumor has very rarely been reported to occur over the forehead. Being a benign tumor, no association of malignant transformation or metastasis has been reported. A 23-year-old male presented with a complaint of a painless non-progressive swelling over the forehead for the past 6 months. On examination, the swelling was 2x2 cm, soft, mobile, non-tender, and non-pulsatile with no skin changes. FNAC did which shows sheets and clusters of adipocytes with abundant foamy cytoplasm and reported as “Hibernoma”. The patient has been asked to follow up and for the last 1 year, the tumor is still non-progressive with no pressure symptoms and hence has not undergone surgery. Hibernoma is a rare benign tumor of brown fat tissue which constitutes only 1.6% of benign lipomatous tumors but their actual prevalence is still unknown. This tumor very rarely may occur in the forehead area although incidence over the forehead has rarely been reported. Since this tumor is slow growing, painless non-progressive; it mostly presents as an asymptomatic tumor. It has to be included in the differential diagnosis of adipocyte-containing tumors to prevent false treatment.

DIFFUSE ECTOPIC DECIDUOSIS MIMICKING AS PERITONEAL CARCINOMATOSIS: A CASE REPORT OF A YOUNG FEMALE WITH MULTIPLE SEROSAL AND OMENTAL NODULES FOUND DURING A CAESARIAN SECTION

Background &amp; Objectives: Ectopic deciduosis refers to an abnormal occurrence of decidual tissue beyond the endometrium, predominantly on the surface of the uterus, fallopian tubes, ovaries and omentum. Diffuse omental and perito-neal involvement is a perplexing manifestation that may mimic peritoneal carcinomatosis. It is not accompanied by any symptoms and complications in most of the cases and does not require treatment. However, rarely it can present with acute abdomen or imitate peritoneal malignancy and, thus, associated with diagnostic difficulties and unnecessary interventions. Aim of this case report is to describe a rare case of peritoneal deciduosis in a young female, found incidentally, during a caesarean section, mimicking metastatic nodules. Afutile hysterec-tomy along with omentectomy was performed.&#x0D; Methods: A case of diffuse ectopic deciduosis mimicking as peritoneal carcinomatosis in a 29 years young female with full term pregnancy was found during a lower segment caesarian section, undertaken in a tertiary care teaching hospital of Lahore, Pakistan. The histopathological diagnosis was based on common technique of paraffin embedding and hematoxylin-eosin staining along with ancillary immune-histochemical evaluation.&#x0D; Results: Histopathological evaluation showed ectopic decidual tissue consisted of solid nests and loosely cohesive aggregates; large polygonal cells with abundant granular eosinophilic cytoplasm; sharply defined cell borders, bland nuclei with dispersed chromatin and single conspicuous nucleoli on the surface of uterus and in omental fat. Weak staining for CD30 was observed in the decidual cell cytoplasm and negative staining for CK and Calretinin in decidual cells was found. Calretinin and CK highlight benign mesothelial cells and help to rule out differentials of mesothelioma and metastatic carcinoma.&#x0D; Conclusion: Peritoneal deciduosis represents a rare entity and it is important to consider this condition in patients, especially in pregnant women, to prevent unnecessary intervention In addition, distinguishing this condition from malignant neoplasms will help in deciding correct treatment options.

Malignant undifferentiated epithelioid neoplasms with MAML2 rearrangements: A clinicopathologic study of seven cases demonstrating a heterogenous entity.

Among mesenchymal tumors, MAML2 gene rearrangements have been described in a subset of composite hemangioendothelioma and myxoinflammatory fibroblastic sarcoma (MIFS). However, we have recently encountered MAML2-related fusions in a group of seven undifferentiated malignant epithelioid neoplasms that do not fit well to any established pathologic entities. The patients included five males and two female, aged 41-71 years old (median 65 years). The tumors involved the deep soft tissue of extremities (hip, knee, arm, hand), abdominal wall, and the retroperitoneum. Microscopically, the tumors consisted of solid sheets of atypical epithelioid to histiocytoid cells with abundant cytoplasm. Prominent mitotic activity and necrosis were present in 4 cases. In 3 cases, the cells displayed hyperchromatic nuclei or conspicuous macronucleoli, and were admixed with background histiocytoid cells and a lymphoplasmacytic infiltrate. By immunohistochemistry (IHC), the neoplastic cells had a nonspecific phenotype. On targeted RNA sequencing, MAML2 was the 3' partner and fused to YAP1 (4 cases), ARHGAP42 (2 cases), and ENDOD1 (1 case). Two cases with YAP1::MAML2 harbored concurrent RAF kinase fusions (RBMS3::RAF1 and AGK::BRAF, respectively). In 2 cases with targeted DNA sequencing, mutations in TP53, RB1 and PTEN were detected in 1 case, and PDGFRB mutations, CCNE1 amplifications and CDKN2A/2B deletion were detected in another case, which showed strong and diffuse PDGFRB expression by IHC. Of the 4 cases with detailed clinical history (median follow-up period 8months), three developed distant metastatic disease (one of which died of disease); one case remained free of disease 3 years following surgical excision. In conclusion, we describe a heterogeneous series of MAML2-rearranged undifferentiated malignant epithelioid neoplasms, a subset of which may overlap with a recently described MIFS variant with YAP1::MAML2 fusions, further expanding the clinicopathologic spectrum of mesenchymal neoplasms with recurrent MAML2 gene rearrangements.