Ovoid Cells Research Articles

The morphogenic protein CopD controls the spatio-temporal dynamics of PBP1a and PBP2b in Streptococcus pneumoniae.

Penicillin-binding proteins (PBPs) are essential for proper bacterial cell division and morphogenesis. The genome of Streptococcus pneumoniae encodes for two class B PBPs (PBP2x and 2b), which are required for the assembly of the peptidoglycan framework and three class A PBPs (PBP1a, 1b and 2a), which remodel the peptidoglycan mesh during cell division. Therefore, their activities should be finely regulated in space and time to generate the pneumococcal ovoid cell shape. To date, two proteins, CozE and MacP, are known to regulate the function of PBP1a and PBP2a, respectively. In this study, we describe a novel regulator (CopD) that acts on both PBP1a and PBP2b. These findings provide valuable information for understanding bacterial cell division. Furthermore, knowing that ß-lactam antibiotic resistance often arises from PBP mutations, the characterization of such a regulator represents a promising opportunity to develop new strategies to resensitize resistant strains.

Non-cutaneous syncytial myoepitheliomas are identical to cutaneous counterparts: a clinicopathologic study of 24 tumors occurring at diverse locations.

Cutaneous syncytial myoepithelioma (CSM) is a rare myoepithelioma variant of skin, characterized by intradermal syncytial growth of spindle cells with a distinct immunophenotype of EMA and S100 positivity and infrequent keratin expression. While CSM was first described as a cutaneous tumor, singular non-cutaneous cases have since been reported in bone. We aimed to investigate the clinicopathological features of this variant across all anatomic sites through a large multi-institutional study. We complied a total of 24 myoepitheliomas with syncytial growth from our files. The tumors occurred in 12 male and 12 female patients (M:F = 1:1), with a median age of 31 years (range, 9-69 years). While the majority of tumors (75%, n = 18) occurred in skin, a significant subset (25%, n = 6) arose in non-cutaneous sites, including bone (n = 3), bronchus/trachea (n = 2), and interosseous membrane of tibia/fibula (n = 1). Tumor size ranged from 0.4 to 5.9 cm. Clinical follow-up (7 patients; range 14-202 months; median 56.5 months) showed a single local recurrence 8 years after incomplete skin excision but no metastases; all patients were alive at the time of last follow-up without evidence of disease. Histologically, all tumors were pink at low-power and characterized by a syncytial growth of bland ovoid, spindled, or histiocytoid cells with eosinophilic cytoplasm and prominent perivascular lymphoplasmacytic inflammation. One-third displayed adipocytic metaplasia (8/24). Rare cytologic atypia was seen but was not associated with increased mitotic activity. All tumors expressed S100, SMA, and/or EMA. Keratin expression was absent in most cases. Molecular analysis was performed in 16 cases, all showing EWSR1-rearrangments. In total, 15/15 (100%) harbored an EWSR1::PBX3 fusion, whereas 1 case EWSR1 FISH was the only molecular study performed. Syncytial myoepithelioma is a rare but recognizable morphologic variant of myoepithelioma which may have a predilection for skin but also occurs in diverse non-cutaneous sites. Our series provides evidence supporting a reappraisal of the term "cutaneous syncytial myoepithelioma," as 25% of patients in our series presented with non-cutaneous tumors; thus, we propose the term "syncytial myoepithelioma" to aid pathologist recognition and avoidance of potentially confusing terminology when referring to non-cutaneous examples. The behavior of syncytial myoepithelioma, whether it arises in cutaneous or non-cutaneous sites, is indolent and perhaps benign with a small capacity for local recurrence.

Understanding Glomangiopericytoma: A Case Report of a Rare Sinonasal Tumor

Introduction: Glomangiopericytoma (GPC) is a benign neoplasm of the sinonasal tract that consists of spindle-shaped to ovoid cells with lobular or nodular growth patterns. GPCs are low-malignant tumors due to limited mitotic activity and atypia, making them less aggressive. The etiology of GPC remains unknown but is associated with factors like steroid use, past trauma, pregnancy, and hypertension. GPC is more common in women and is usually diagnosed in the sixth and seventh decades of life. Case Presentation: This article presents a case of a 47-year-old woman with a history of type-2 diabetes and nasal obstruction who was diagnosed with glomangiopericytoma (GPC), a rare sinonasal tumor. Computed tomography revealed a vascular mass, and complete surgical resection was achieved via a trans-nasal approach. The diagnosis was confirmed through positive β-catenin staining and negative S100p and STAT6 with a low Ki67 proliferation index. The patient experienced post-operative pain, anosmia, and ageusia, which were treated successfully. This case highlights the clinicopathologic characteristics, clinical and therapeutic aspects, surgical interventions, and differential diagnosis of GPC, a rare disease with limited reports. Conclusion: Glomangiopericytomas are benign sinonasal tumors often mistaken for other neoplasms. Diagnosis is challenging but possible through excision or biopsy with histopathological examination. Endoscopic surgery with follow-up is the recommended treatment, with recurrence occurring up to 12 years post-surgery. CTNNB1 gene mutations and β-catenin nuclear expression are recent diagnostic markers. GPC has a high survival rate and low metastasis, but patients should be closely monitored. This case report underscores the importance of comprehensive diagnosis and management for these rare tumors.

BROWN TUMORS IN THE JAWS AS THE FIRST CLINICAL SIGN OF HYPERPARATHYROIDISM

Brown tumor of hyperparathyroidism is a bone lesion that results from abnormal bone metabolism. Our study describes a case of a 26-year-old man presenting clinically facial deformity and bone expansion in the jaws. Cone-beam computed tomography exhibited an expansive, ill-defined multilocular hypodense lesion in the maxilla, and a well-defined unilocular hypodense lesion in the mandible. Medical history was not contributive. An incisional biopsy was done, and histopathological analysis of both lesions displayed abundant osteoclast-type multinucleated giant cells intermingled with ovoid and spindle-shaped mononuclear cells in a fibrovascular background, suggestive of central giant cell lesions. Laboratory examination revealed elevated serum levels of parathyroid hormone and calcium, and a decreased level of phosphorus. Based on clinical, radiologic, microscopic, and biochemical findings, the diagnosis was brown tumor of hyperparathyroidism. The patient had undergone excision of right lower parathyroid and had a partially significant reduction in the jaws’ tumors after 6 months of follow-up. Brown tumor of hyperparathyroidism is a bone lesion that results from abnormal bone metabolism. Our study describes a case of a 26-year-old man presenting clinically facial deformity and bone expansion in the jaws. Cone-beam computed tomography exhibited an expansive, ill-defined multilocular hypodense lesion in the maxilla, and a well-defined unilocular hypodense lesion in the mandible. Medical history was not contributive. An incisional biopsy was done, and histopathological analysis of both lesions displayed abundant osteoclast-type multinucleated giant cells intermingled with ovoid and spindle-shaped mononuclear cells in a fibrovascular background, suggestive of central giant cell lesions. Laboratory examination revealed elevated serum levels of parathyroid hormone and calcium, and a decreased level of phosphorus. Based on clinical, radiologic, microscopic, and biochemical findings, the diagnosis was brown tumor of hyperparathyroidism. The patient had undergone excision of right lower parathyroid and had a partially significant reduction in the jaws’ tumors after 6 months of follow-up.

CENTRAL GIANT CELL LESION IN THE MAXILLA TREATED WITH CORTICOSTEROID INFILTRATION

The etiopathogenesis of some non-neoplastic benign proliferative lesions remain uncertain. This is the case of giant cell lesions (CGCL), which, despite their benign and asymptomatic nature, may display aggressive behavior. Clinical and radiographic aspects may vary greatly, though histopathologically, few to many multinucleated giant cells, fibroblasts, ovoid mesenchymal cells, and loosely arranged stroma are often observed. This study aimed to present the satisfactory outcome of a CGCL in the maxilla treated exclusively with intralesional corticosteroid injections in a 30-year-old patient, who was admitted to our center with an asymptomatic swelling in the region of teeth 14 and 15 and displaying radiographic features of an odontogenic cyst. Even though surgery is the first-line treatment option, intralesional corticosteroid was an effective strategy to manage a relatively large lesion. The etiopathogenesis of some non-neoplastic benign proliferative lesions remain uncertain. This is the case of giant cell lesions (CGCL), which, despite their benign and asymptomatic nature, may display aggressive behavior. Clinical and radiographic aspects may vary greatly, though histopathologically, few to many multinucleated giant cells, fibroblasts, ovoid mesenchymal cells, and loosely arranged stroma are often observed. This study aimed to present the satisfactory outcome of a CGCL in the maxilla treated exclusively with intralesional corticosteroid injections in a 30-year-old patient, who was admitted to our center with an asymptomatic swelling in the region of teeth 14 and 15 and displaying radiographic features of an odontogenic cyst. Even though surgery is the first-line treatment option, intralesional corticosteroid was an effective strategy to manage a relatively large lesion.

A rare case of ocular and testicular T-cell lymphoma in a hermaphrodite koi carp (Cyprinus carpio Linnaeus 1758): clinical, histopathological, and immunohistochemical study

BackgroundLymphatic neoplasia may occur in various types, such as lymphoma, lymphosarcoma, lympholeukemia, and plasmacytoid leukemia. Lymphoma, defined as a malignant tumour of lymphoid tissue, has been found in a number of fish families including Esocidae and Salmonidae. However, the occurrence of lymphoma is rare in those belonging to the Cyprinidae. A final diagnosis of ocular and testicular T-cell lymphoma in the present study was based on the clinical signs, morphology, and texture of the tumour masses in the macroscopic and microscopic examinations. In addition, histopathological and immunohistochemical findings corresponded to T-cell lymphoma characteristics.Case presentationA 2-year-old hermaphrodite koi carp (Cyprinus carpio Linnaeus 1758) with a large ocular mass and severe exophthalmia in the right eye was referred to the Ornamental Fish Clinic in October 2020. Under anesthesia, enucleation was performed. 57 days after enucleation of the right eye, exophthalmia in the left eye was discovered. 221 days after surgery, the fish was discovered to be dead. At necropsy, a large soft tissue mass attached to the left testis was discovered. There were also small whitish nodules on the surface of the liver. Histopathology revealed a hypercellular ocular mass with scant connective tissue. The sections also revealed multifocal hemorrhages, round to ovoid neoplastic cells, mild-to-moderate anisokaryosis and anisocytosis, and mitotic figures. Basophilic neoplastic cells were found in blood vessels within the testicular mass, raising the possibility of systemic spread. The liver showed microscopic metastasis with morphologic similarities to the ocular and testicular tumors. The neoplastic cells infiltrating the left and right eyes as well as the testicular mass were immunohistochemically positive for CD3 but negative for CD20. The masses were diagnosed as T-cell lymphoma based on histopathological and immunohistochemical findings.ConclusionsThis case report provides the first evidence of clinical, histopathological, morphological, and immunohistochemical findings of an ocular and testicular T-cell lymphoma in a hermaphrodite koi carp (Cyprinus carpio) in Iran.

Uterine Endometrial Stromal Tumors With Pure Low-Grade Morphology Harboring YWHAE::NUTM2 Fusions: Report of a Case Series Emphasizing Potential for High-Grade Transformation and Aggressive Behavior.

Uterine endometrial stromal sarcomas (ESS) with YWHAE::NUTM2 gene fusions are typically morphologically high-grade tumors composed of atypical round cells, sometimes associated with a low-grade fibromyxoid component; they are currently included in the category of high-grade ESS (HGESS). We report 5 morphologically pure low-grade endometrial stromal tumors harboring YWHAE::NUTM2 fusions, including 1 endometrial stromal nodule (ESN) and 4 low-grade endometrial stromal sarcomas (LGESS), an association only occasionally reported previously. Patients ranged from 30 to 51 (mean=43) years and tumors from 4.5 to 7.5cm (mean=5.7). All were stage I at diagnosis (confined to the uterus). Microscopically, the 4 LGESS showed extensive "tongue-like" invasion of the myometrium, and the ESN was entirely confined to the endometrium with no myometrial invasion. All tumors were composed entirely of morphologically uniform bland ovoid cells resembling proliferative endometrial stroma. A fibromyxoid component was seen in 1 LGESS and the ESN; in the LGESS, this was the sole component. Atypical round cells characteristic of YWHAE::NUTM2 HGESS were not identified. Mitotic count ranged from <1 to 13 per 10 high-power fields (mean: 3). CD10 was positive in 2/4 (focal), estrogen receptor in 5/5 (focal=1; diffuse=4), progesterone receptor in 5/5 (focal=1; diffuse=4) and cyclin D1 was diffusely positive in 3/4. Follow-up was available in all 5 patients and ranged from 6 to 159 months (mean=72). Two patients with LGESS had recurrent disease at 15 and 155 months; 1 showed predominantly LGESS with rare round cells in the initial recurrence and pure HGESS in a subsequent recurrence, while the other patient's recurrent tumor was predominantly HGESS (90%) in a background of focal fibromyxoid LGESS (10%). Both patients rapidly progressed and died of disease within 5 months of high-grade recurrence. We show that rare cases of morphologically pure low-grade endometrial stromal tumors, some but not all with a fibromyxoid component, harbor YWHAE::NUTM2 fusions and may recur rapidly, with transformation to HGESS and aggressive behavior. Our findings suggest that at least a subset of YWHAE::NUTM2 HGESS evolves from LGESS. We suggest that cyclin D1 and CD10 staining should be performed in all LGESS. Diffuse staining for cyclin D1 and/or negative or focal staining for CD10 should suggest the possibility of a YWHAE::NUTM2 fusion, and appropriate molecular testing should be undertaken. Since no single morphological or immunohistochemical parameter is entirely sensitive for fusion status, we also suggest that testing for a YWHAE::NUTM2 gene fusion should be considered in all cases of LGESS and, if a fusion is present, this should raise the possibility of subsequent high-grade transformation and aggressive behavior, even though such cases should still be categorized as LGESS. Although seemingly rare, ESN and LGESS with YWHAE::NUTM2 fusions may be under-recognized due to a lack of routine fusion testing.

Extraenteric Malignant Gastrointestinal Neuroectodermal Tumor—A Clinicopathologic and Molecular Genetic Study of 11 Cases

Malignant gastrointestinal neuroectodermal tumors (MGNETs), also known as “gastrointestinal clear cell sarcoma–like tumors”, are very rare, aggressive sarcomas characterized by enteric location, distinctive pathologic features, and EWSR1/FUS::ATF1/CREB1 fusions. Despite identical genetics, the clinicopathologic features of MGNET are otherwise quite different from those of clear cell sarcoma of soft parts. Only exceptional extraenteric MGNET (E-MGNET) has been reported. We report a series of 11 E-MGNETs, the largest to date. Cases diagnosed with MGNET and occurring in nonintestinal locations were retrieved. A clinical follow-up was obtained. The tumors occurred in 3 men and 8 women (range, 14-70 years of age; median, 33 years) and involved the soft tissues of the neck (3), shoulder (1), buttock (2), orbit (1), tongue/parapharyngeal space (1), urinary bladder (1), and falciform ligament/liver (1). Tumors showed morphologic features of enteric MGNET (small, relatively uniform, round to ovoid cells with round, regular nuclei containing small nucleoli growing in multinodular and vaguely lobular patterns, with solid, pseudoalveolar, and pseudopapillary architecture). Immunohistochemical results were S100 protein (11/11), SOX10 (11/11), synaptophysin (3/10), CD56 (7/9), CD117 (3/9), DOG1 (0/4), ALK (4/8), chromogranin A (0/10), HMB-45 (0/11), Melan-A (0/11), tyrosinase (0/4), and MiTF (0/11). Next-generation sequencing results were EWSR1::ATF1 (7 cases), EWSR1::CREB1 (3 cases), and EWSR1::PBX1 (1 case). The EWSR1::PBX1-positive tumor was similar to other cases, including osteoclast-like giant cells, and negative for myoepithelial markers. A clinical follow-up (range, 10-70 months; median, 34 months) showed 4 patients dead of disease (10.5, 12, 25, and 64 months after diagnosis), 1 patient alive with extensive metastases (43 months after diagnosis), 1 patient alive with persistent local disease (11 months after diagnosis), and 4 alive without disease (10, 47, 53, and 70 months after diagnosis). One case is too recent for the follow-up. The clinicopathologic and molecular genetic features of rare E-MGNET are essentially identical to those occurring in intestinal locations. Otherwise, typical E-MGNET may harbor EWSR1::PBX1, a finding previously unreported in this tumor type. As in enteric locations, the behavior of E-MGNET is aggressive, with metastases and/or death from disease in at least 50% of patients. E-MGNET should be distinguished from clear cell sarcoma of soft parts and other tumors with similar fusions. ALK expression appears to be a common feature of tumors harboring EWSR1/FUS::ATF1/CREB1 fusion but is unlikely to predict the therapeutic response to ALK inhibition. Future advances in our understanding of these unusual tumors will hopefully lead to improved nomenclature.

Is heterogeneity in large-scale bioreactors a real problem in recombinant protein synthesis by Pichia pastoris?

Culture medium heterogeneity is inherent in industrial bioreactors. The loss of mixing efficiency in a large-scale bioreactor yields to the formation of concentration gradients. Consequently, cells face oscillatory culture conditions that may deeply affect their metabolism. Herein, cell response to transient perturbations, namely high methanol concentration combined with hypoxia, has been investigated usinga two stirred-tank reactor compartiments(STR-STR) scale-down system and a Pichia pastoris strain expressing the gene encoding enhanced green fluorescent protein (eGFP) under the control of the alcohol oxidase 1 (AOX1) promoter. Cell residence times under transient stressing conditions were calculated based on the typical hydraulic circulation times of bioreactors of tens and hundreds cubic metres. A significant increase in methanol and oxygen uptake rates was observed as the cell residence time was increased. Stressful culture conditions impaired biomass formation and triggered cell flocculation. More importantly, both expression levels of genes under the control of pAOX1 promoter and eGFP specific fluorescence were higher in those oscillatory culture conditions, suggesting that those a priori unfavourable culture conditions in fact benefit to recombinant protein productivity. Flocculent cells were also identified as the most productive as compared to ovoid cells. KEY POINTS: • Transient hypoxia and high methanol trigger high level of recombinant protein synthesis • In Pichia pastoris, pAOX1 induction is higher in flocculent cells • Medium heterogeneity leads to morphological diversification.

GAB1::ABL1 fusions define a distinctive soft tissue neoplasm, with variable perineurial differentiation, and a predilection for children and young adults.

Although well known as a fusion partner in hematological malignancies, fusion genes involving the ABL proto-oncogene 1 (ABL1), mapping to chromosomal region 9q34.12, have only been anecdotally reported in five soft tissue tumors. These neoplasms have been variously reported as perineurioma, angiofibroma, and solitary fibrous tumor, and all have harbored a GAB1::ABL1 gene fusion; however, the nosology and clinicopathological characteristics of soft tissue tumors carrying this rare fusion have not been delineated. We herein describe eight tumors containing the GAB1::ABL1 fusion and review previously reported cases in a series to define their morphological spectrum, address immunohistochemical evidence for a line of differentiation, with special reference to the presence or absence of a perineurial immunophenotype, and gather insight into their behavior. The patients included four females and four males, aged 13-37 years (median, 24 years). Two cases each originated in the shoulder area, trunk, hands, and lower extremities, with a size range of 1.5-8cm (median, 3.4cm). Four tumors were deep and four superficial. All tumors were morphologically similar, being composed of bland fibroblast-like spindle to ovoid cells diffusely arranged in a paucivascular fibrous to fibromyxoid stroma with variable resemblance to soft tissue perineurioma. Mitotic activity was generally low (0-8 mitoses in 10 high-power fields [HPFs]; median, 1). All lesions had at least focally infiltrative margins, but they otherwise lacked pleomorphism and necrosis. Immunohistochemistry showed focal reactivity for CD34 (5/7), epithelial membrane antigen (EMA) (3/8), claudin1 (2/3), GLUT1 (4/6), and S100 (2/7); other markers, including MUC4 (0/7), desmin (0/9), and smooth muscle actin(SMA) (0/4), were negative. RNA sequencing revealed a GAB1::ABL1 fusion in all cases with exon 6 of GAB1 fused to exon 2 of ABL1. Treatments included various forms of surgical intervention in seven cases; one tumor was biopsied only. Limited follow-up was available for five patients. One tumor regrew rapidly within 1 month to 1.5cm after an initial marginal excision and was re-excised with close margins. Four patients were disease-free at 1, 3, 14, and 25 months of follow-up. Metastases have not, to date, been observed. This series characterizes "GAB1::ABL1 fusion-positive spindle cell neoplasm" as a distinct entity, with overlapping features with soft tissue perineurioma and predilection for children and young adults.

Next generation sequencing for an unusual and rare sarcoma: a case report

We present a case of a 49-year-old woman who had a well circumscribed, 10 mm subcutaneous nodule removed from her right shoulder at the junction of adipose and skeletal muscle tissue. Microscopic findings showed a circumscribed tumour with ovoid and spindled cells, with minimal cytoplasm and pleomorphism.

Shear-enhanced sorting of ovoid and filamentous bacterial cells using pinch flow fractionation.

In this paper, we experimentally investigate the influence of the flow rate on the trajectory of ovoid and filamentous bacterial cells of E. coli in a low aspect ratio pinch flow fractionation device. To that aim, we vary the Reynolds number over two orders of magnitude, while monitoring the dynamics of the cells across our device. At low flow rates, filamentous cells adopt several rotational motions in the pinched segment, which are induced both by the shear rate and by their close interactions with the nearest wall. As a result, the geometrical centre of the filamentous cells deviates towards the centre of the channel, which increases their effective sorting diameter depending on the length of their major axis as well as on the rotational mode they adopt in the pinch. As the flow rate increases, particles are forced to align vertically in the pinch, in the direction of the main shear gradient, which reduces the amplitude of the lateral deviation generated by their rotation. The trajectory of the particles in the expansion is directly determined by their position at the pinch outlet. As a consequence, the position of the filamentous cells at the outlet of the device strongly depends on the flow rate as well as on the length of their major axis. Based on these observations we optimized the flow conditions to successfully extract an ultra high purity sample of filamentous cells from a solution containing mainly ovoid cells.

Bone and soft tissue tumors: clinicoradiologic-pathologicmolecular-genetic correlation of novel fusion spindled, targetable-ovoid, giant-cell-rich, and round cell sarcomas.

New entities in the classification of bone and soft tissue tumors have been identified by use of advanced molecular-genetic techniques,including next-generation sequencing. Clinicoradiologic and pathologic correlation supports diagnostic classification. Tumors from four morphologically grouped areas are selected to enhance diagnosis and awareness among the multidisciplinary team. These include select round cell tumors, spindle cell tumors, targetable tyrosine kinase/RAS::MAPK pathway-ovoid (epithelioid to spindled)tumors, and giant-cell-rich tumors of bone and soft tissue. Round cell tumors of bone and soft tissue include prototypical Ewing sarcoma, newer sarcomas with BCOR genetic alteration and CIC-rearranged, as well as updates onFUS/EWSR1::NFATc2, an EWSR1 non-ETS tumor that is solid with additional amplified hybridization signal pattern of EWSR1.This FUS/EWSR1::NFATc2 fusion hasnow been observed in seemingly benign to low-grade intraosseous vascular-rich and simple (unicameral) bone cyst tumors. Select spindle cell tumors of bone and soft tissue include rhabdomyosarcoma with FUS/EWSR1::TFCP2, an intraosseous high-grade spindle cell tumor without matrix. Targetable tyrosine-kinase or RAS::MAPK pathway-tumors of bone and soft tissue include NTRK, ALK, BRAF, RAF1, RET, FGFR1, ABL1, EGFR, PDGFB,and MET with variable ovoid myopericytic to spindled pleomorphic features and reproducible clinicopathologic and radiologic clues to their diagnosis. Giant-cell-rich tumors of bone, joint, and soft tissue are now respectivelycharacterized by H3F3A mutation, CSF1 rearrangement (targetable), and HMGA2::NCOR2 fusion. This article is an update for radiologists, oncologists, surgeons, and pathologists to recognize these novel ovoid, spindled, giant-cell-rich, and round cell tumors, for optimal diagnostic classification and multidisciplinary team patient care.

Extranodal Follicular Dendritic Cell Sarcoma of the Head and Neck Region: A Clinicopathological Study of 7 Cases.

Background. Follicular dendritic cell (FDC) sarcoma is a rare neoplasm arising from follicular dendritic cells (FDCs). It can be nodal or extranodal. Histological diagnosis of extranodal FDC sarcoma in the head and neck region is challenging and a significant percentage are misdiagnosed. Objectives. To report clinicopathological features of head and neck extranodal FDC sarcoma cases and discuss differential diagnoses. Methods. Seven head and neck extranodal FDC sarcomas were retrieved and clinicopathological features were noted. Results. Two tumors each involved parapharyngeal space and tonsil while remaining cases involved the parotid, soft tissue of neck and oropharynx. Age range was 12 to 79 years (mean and median age were 40 and 44 years respectively) and there was a male predilection (6 males: 1 female). All showed spindle to ovoid cells arranged in fascicles, whorls and/or storiform pattern. Mitoses ranged from 3 to 20/mm2. All tumors expressed CD21 and CD23. Two patients died of their disease at 9 and 16 months. Both had tumors larger than 5 cm with ≥10 mitoses/mm2. Three patients were alive at 12, 44 and 184 months. Conclusions. There was a distinct male predominance in our cohort. FDC sarcoma should be included in the differential diagnosis of spindle cell extranodal neoplasms in the head and neck with a whorled growth pattern and intratumoral lymphocytes. Head and neck region tumors show similar clinicopathologic characteristics as their counterparts at other locations with potential for aggressive behavior especially in tumors greater than 5 cm in size and with high mitotic rates.

TMET-31. CHOLESTEROL ESTERIFICATION IN A PATIENT WITH DIFFUSE ASTROCYTOMA PROGRESSING TO GLIOBLASTOMA

Abstract Metabolic profiles of diffuse astrocytoma and recurrent tumor tissues were compared in a patient with diffuse astrocytoma who showed tumor recurrence and progressed to glioblastoma (GBM). The patient presented with a diffuse infiltrating tumor and was operated in April 2018. The pathology report showed that the tumor was a diffusely infiltrating astrocytoma with Ki-67 of 5% (WHO Grade II). In addition, the molecular testing results indicated that the tumor was IDH1wt with TERTp mutation and showed an indeterminate MGMT promoter status. Given diffuse brain involvement and IDH1wt status, an aggressive behavior was suggested for this tumor. After ~3.5 years (January 2022), the MRI examination showed tumor recurrence and the patient underwent craniotomy for the resection of the recurrent tumor. The pathology report showed a high-grade glial neoplasm composed of ovoid tumor cells with nuclear pleomorphism (GBM, WHO Grade IV). We collected the tumor specimens from both surgeries and compared the metabolic profiles using 1H NMR spectroscopy. The tumor specimens were extracted using methanol-chloroform (2:1 ratio) extraction-method. The methanol-layer of the recurrent tumor showed decreased levels of N-acetylaspartate (NAA) and myo-inositol, and the elevated levels of phosphocholine (PC) and glycine, compared to the diffuse astrocytoma. Decreased NAA and elevated PC and glycine are metabolic features of high-grade gliomas, suggesting progression of the low-grade astrocytoma to GBM. The chloroform-layers of both tumors showed the presence of cholesterol; however, cholesteryl ester (CE) was detected only in the recurrent tumor (GBM). The ratio of CE to cholesterol was 0.44, suggesting that 44% of cholesterol pool was esterified in GBM. Cholesterol esterification is dysregulated in GBM and targeting this metabolic pathway using AcylCoA:cholesterol acyltransferase (ACAT) inhibitors would be promising in the treatment of GBM and astrocytomas with TERTp mutation which transform to GBM.

Angiomatoid Fibrous Histiocytoma with EWSR1 Rearrangement in an Unusual Location

Abstract Introduction/Objective Angiomatoid fibrous histiocytoma (AFH) is a rare mesenchymal neoplasm most often arising in the superficial extremities of children and young adults. AFH can mimic clinical, histologic, and radiologic presentation of several different tumors, therefore diagnosis can be quite challenging. Methods/Case Report We report the case of a 32-year-old woman with no significant medical history who presented with three days of right upper quadrant pain. Radiologic studies showed a 2.3 centimeter right lower lobe soft tissue nodule abutting the right lower lobe bronchus. Results (if a Case Study enter NA) Subsequent lobectomy with mediastinal lymph node dissection was performed. Histopathologic examination of the right middle and lower lobes revealed a fibrohistiocytic appearing neoplasm with bland nuclear features and brisk associated lymphoplasmacytic and histiocytic infiltrate. Given the suspicion for AFH, fluorescent in situ hybridization for EWSR1 and FUS were performed at an outside facility with detection of EWSR1 gene rearrangement supporting the diagnosis of AFH. Conclusion AFH is a rare soft tissue neoplasm that is often indolent but intermediate in potential given the rare possibility of metastasis. While most common in superficial extremities, increasing unusual anatomic sites are being reported. Histologically, the tumor can show a spectrum of morphologic patterns including nodules to sheets of often monomorphic bland, spindle or ovoid cells in an inflammatory background and with associated fibrous pseudocapsule. Three characteristic chromosomal translocations have been identified: EWSR1-CREB1, EWSR1-ATF1 and FUS- ATF1. Treatment is wide surgical excision or radiotherapy if unresectable. The differential diagnosis can be broad with a spectrum from reactive, benign lesions to malignant neoplasms, including a variety of sarcomas.

Malignant Dural Solitary Fibrous Tumor; An Exceedingly Rare Entity

Abstract Introduction/Objective A solitary fibrous tumor (SFT) is an extremely rare mesenchymal neoplasm, accounting for &amp;lt;1% of all primary CNS tumors. Most SFT is dural-based and occurs predominantly in the fourth to sixth decade of life. Here, we present a case of a dural solitary fibrous tumor. Methods/Case Report A 28-year-old male presented with intermittent throbbing headache, nausea, and vomiting. Imaging revealed a large, well-circumscribed left parafalcine, dural-based multilobulated, solid, and cystic mass. The patient underwent craniotomy with mass resection. Preliminary intraoperative findings were of a spindle cell neoplasm. Histopathologic examination showed hypercellular neoplasm composed of the spindle to ovoid cells with a high nuclear to cytoplasmic ratio and limited intervening stroma arranged in a haphazard pattern with prominent branching staghorn vasculature. Focal areas of necrosis and mitotic counts of 8/10 high power field were also seen. The lesional cells showed focal cytoplasmic CD34 expression and strong STAT6 nuclear expression. Finally, a diagnosis of SFT, haemangiopericytoma phenotype classified as grade 3, was made. Results (if a Case Study enter NA) NA Conclusion Most SFTs are considered clinically benign (grade 1 tumors) with favorable outcomes after complete resection. However, haemangiopericytoma phenotype with hypercellularity, necrosis, and elevated mitotic count (&amp;gt; 4/10 HPF) is known to have an increased risk of local recurrence and rare metastasis, requiring patients to receive adjuvant radiotherapy after resection for longer progression-free survival. Therefore, it is vital to be aware of this entity for optimal management and more active systemic surveillance in patients with high-grade SFT tumors. Our patient is currently doing well post-adjuvant radiotherapy and is under active annual surveillance.

Angiomatoid Fibrous Histiocytoma (AFH) of the Right Arm: An Exceptional Case with Pulmonary Metastasis and Confirmatory EWSR1::CREB1 Translocation.

Angiomatoid fibrous histiocytoma (AFH) is a rare neoplasm described for the first time by Enzinger in 1979, and classified by World Health Organization 2020 as intermediate malignant potential neoplasm. It mostly occurs in the subcutis and is characterized by varying proportions of epithelioid, ovoid and spindle cells in a nodular and syncytial growth pattern, with some hemorrhagic pseudovascular spaces. In this paper, we report the clinical case of a 62-year-old man who presented with AFH on the right arm, and relapsed three years after first surgical excision. After a further three years, the patient presented with an intramuscular localization of AFH, and 12 months after this, a pulmonary metastasis of AFH was diagnosed. Given the rarity of the spreading of AFH, we performed Fluorescence In Situ Hybridization (FISH) and we detected EWSR1::CREB1 gene fusion.

What is your diagnosis? Ovarian mass in a mare.

What is your diagnosis? Ovarian mass in a mare.

The use of readily available laboratory tests for the identification of the emerging yeast Candida auris in Mexico.

Identification of the emerging multidrug-resistant yeast Candida auris is challenging. Here, we describe the role of the Mexico national reference laboratory Instituto de Diagnóstico y Referencia Epidemiológicos Dr. Manuel Martínez Báez (InDRE) and the Mexican national laboratory network in the identification of C. auris. Reference identification of six suspected isolates was done based on phenotypic and molecular laboratory methods, including growth in special media, evaluation of isolate micromorphology, and species-specific PCR and pan-fungal PCR and sequencing. The four C. auris isolates identified were able to grow on modified Sabouraud agar with 10% NaCl incubated at 42 °C. With one exception, isolates of C. auris were spherical to ovoid yeast-like cells and blastoconidia, with no hyphae or pseudohyphae on cornmeal agar. C. auris isolates were resistant to fluconazole. Species-specific and pan-fungal PCR confirmed isolates as C. auris. Sequence analysis revealed the presence of two different C. auris clades in Mexico, clade I (South Asia) and clade IV (South America).