Epithelioid Cell Tumor Research Articles

Ceus features of liver pecoma: a case report and literature review.

Perivascular epithelioid cell neoplasms (PEComas) and epithelioid angiomyolipomas (EAMLs) are two different denominations for the same "mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells". Hepatic PEComa/EAML is a very rare neoplasm, and only 29 case reports of hepatic PEComa and 25 of hepatic EAML have been reported in the current literature. A clear female predominance with a mean age at diagnosis of 42.5years old can be observed by literature review. Ultrasound (US) examination was the first-line diagnostic technique in most of the cases of hepatic PEComa, but it was documented in very few cases of hepatic EAML. A great variability in the ultrasonographic B-mode, color Doppler and contrast-enhanced ultrasonography (CEUS) features of hepatic PEComa/EAML emerges. Computed tomography and magnetic resonance were the most common used techniques to confirm the nature of the hepatic lesion, even if the anatomo-pathological examination was the only technique to display a certainty diagnosis and to differentiate hepatic PEComa/EAML from benign and malignant hepatic lesions. The great majority of hepatic PEComas/EAMLs are surgically treated without any adjuvant therapy.

PAX5 and CD70 are expressed in thymic carcinoma but not in atypical thymoma (WHO type B3 thymoma): an immunohistochemical analysis of 60 cases

AimsThymic carcinoma and atypical thymoma (WHO type B3 thymoma) are unusual tumours the separation of which may be challenging in small biopsies. Both tumours consist of epithelioid tumour cells that...

Cardiac Angiosarcoma with Unusual Cytologic Features Causing Cardiac Tamponade in a Young Adult Patient

Abstract Introduction/Objective Cardiac angiosarcoma is a rare endothelial malignancy with poor prognosis, frequent metastasis, and short median survival of only a few months. The disease has a wide age spectrum and can occur in young adult patients. The cytological diagnosis of cardiac angiosarcomas is challenging as cases are rare and its cytology is not extensively described or reported in literature. Here, we describe a rare case of cardiac angiosarcoma with unusual cytologic features. Methods/Case Report Our patient is a 30 year old male presenting with three days of worsening dyspnea and palpitations and was discovered on ultrasound to have large pericardial effusion compressing the right ventricle and causing cardiac tamponade. CT/MRI imaging revealed a 4.5 x 4.3 x 2.6 cm mass inside the right ventricle with extra- cardiac invasion through the pericardium and into the anterior mediastinum. Pericardiocentesis yielded 1.5 liters of hemorrhagic, brown, pericardial fluid with elevated LDH and protein levels. Cytology of the pericardial fluid revealed numerous tumor cells occurring singly or in monolayered, acinar clusters or cohesive spheres containing amorphous, eosinophilic cores made of collagen as evidenced on trichrome stain. The tumor cells possessed hyperchromatic, irregular, variably sized nuclei, prominent nucleoli, and cytoplasmic vacuoles. The tumor cells were positive for vimentin, CD31, and CD34, and showed high Ki67 proliferation index > 50%. A catheter-mediated biopsy of the right ventricular mass revealed spindled and epithelioid tumor cells strongly positive for CD31, CD34, and vimentin, focally positive for Factor VIII and AE1/AE3, and showing high Ki67 proliferation index of roughly 50%. The cytological, histological, and immunohistochemical findings were most consistent with cardiac angiosarcoma as the diagnosis. The patient eventually developed worsening chronic left chest pain and expired from cardiac arrest six months after his diagnosis. Results (if a Case Study enter NA) NA Conclusion We report a rare case of cardiac angiosarcoma with unusual cytologic features, manifesting as acinar clusters and cohesive spheres with collagenous cores that are not typical of malignant endothelial neoplasms. Currently there are no effective, standardized therapies that can significantly prolong survival for this malignancy, and treatment is often palliative. The cytological diagnosis of cardiac angiosarcoma is challenging given the rarity of this disease and the paucity of literature describing its cytology.

Melatonin Receptor Expression in Primary Uveal Melanoma.

Melatonin, noted for its anti-cancer properties in various malignancies, including cutaneous melanoma, shows promise in Uveal melanoma (UM) treatment. This study aimed to evaluate melatonin receptor expression in primary UM and its association with UM-related mortality and prognostic factors. Immunohistochemical analysis of 47 primary UM tissues showed low expression of melatonin receptor 1A (MTNR1A) and melatonin receptor 1B (MTNR1B), with MTNR1A significantly higher in patients who succumbed to UM. Analysis of TCGA data from 80 UM patients revealed RNA expression for MTNR1A, retinoic acid-related orphan receptor alpha (RORα), and N-ribosyldihydronicotinamide:quinone oxidoreductase (NQO2), but not MTNR1B or G protein-coupled receptor 50 (GPR50). Higher MTNR1A RNA levels were observed in patients with a BRCA1 Associated Protein 1 (BAP1) mutation, and higher NQO2 RNA levels were noted in patients with the epithelioid tumor cell type. However, Kaplan-Meier analysis did not show distinct survival probabilities based on receptor expression. This study concludes that UM clinical samples express melatonin receptors, suggesting a potential mechanism for melatonin's anti-cancer effects. Despite finding higher MTNR1A expression in patients who died of UM, no survival differences were observed.

EWSR1::ATF1 fusions characterize a group of extra-abdominal epithelioid and round cell mesenchymal neoplasms, phenotypically overlapping with sclerosing epithelioid fibrosarcomas, and intra-abdominal FET::CREB fusion neoplasms.

With the increasing use of next generation sequencing in soft tissue pathology, particularly in neoplasms not fitting any World Health Organization (WHO) category, the spectrum of EWSR1 fusion-associated soft tissue neoplasms has been expanding significantly. Although recurrent EWSR1::ATF1 fusions were initially limited to a triad of mesenchymal neoplasms including clear cell sarcoma of soft tissue, angiomatoid fibrous histiocytoma and malignant gastrointestinal neuroectodermal tumor (MGNET), this family has been expanding. We herein describe 4 unclassified extra-abdominal soft tissue (n = 3) and bone (n = 1) neoplasms displaying epithelioid and round cell morphology and carrying an EWSR1::ATF1 fusion. Affected were 3 males and 1 female aged 20-56years. All primary tumors were extra-abdominal and deep-seated (chest wall, mediastinum, deltoid, and parapharyngeal soft tissue). Their size ranged 4.4-7.5cm (median, 6.2). One patient presented with constitutional symptoms. Surgery with (2) or without (1) neo/adjuvant therapy was the treatment. At last follow-up (8-21months), 2 patients developed progressive disease (1 recurrence; 1 distant metastasis). The immunophenotype of these tumors is potentially misleading with variable expression of EMA (2 of 3), pankeratin (2 of 4), synaptophysin (2 of 3), MUC4 (1 of 3), and ALK (1 of 3). All tumors were negative for S100 and SOX10. These observations point to the existence of heretofore under-recognized group of epithelioid and round cell neoplasms of soft tissue and bone, driven by EWSR1::ATF1 fusions, but distinct from established EWSR1::ATF1-associated soft tissue entities. Their overall morphology and immunophenotype recapitulate that of the emerging EWSR1/FUS::CREB fusion associated intra-abdominal epithelioid/round cell neoplasms. Our cases point to a potentially aggressive clinical behavior. Recognizing this tumor type is mandatory to delineate any inherent biological and/or therapeutic distinctness from other, better-known sarcomas in the differential diagnosis including sclerosing epithelioid fibrosarcoma.

PEComa With MITF Overexpression: Clinicopathologic and Molecular Analysis of a Series of 36 Cases.

Perivascular epithelioid cell neoplasms (PEComas) are tumors of uncertain cell lineage that occur across a wide age range, at a variety of anatomic sites, and with a female predominance. Most PEComas are associated with dysregulation of the mTOR pathway, most commonly through inactivating mutations of TSC2 or TSC1 . However, a small subset of PEComas are instead associated with TFE3 gene fusions. MITF is closely related to TFE3 and is frequently overexpressed in PEComas, often in a mutually exclusive manner with TFE3. Here we report the clinical, histopathologic, and molecular features of MITF-overexpressing PEComas in a series of 36 cases. The clinical and morphologic features were comparable to conventional PEComa, although the immunohistochemical profile was notable for the relatively limited expression of melanocytic markers, a surprising finding given that MITF is the master regulator of melanocytic differentiation. At the molecular level, 20 cases (56%) showed supernumerary copies of the MITF gene, suggesting a potential explanation for MITF overexpression. A putative genetic driver event within the mTOR pathway was identified in 11 of 15 cases (73%) analyzed by DNA or RNA sequencing. Interestingly, the malignant PEComas showed 2 distinguishing molecular features: they were associated with a complex chromosomal copy number profile, and they tended to show additional genetic changes, most commonly inactivating events involving TP53 , RB1 , and ATRX . These results elucidate key features of PEComas showing MITF overexpression, begin to explain the molecular basis for MITF overexpression in some PEComas and identify potential molecular correlates for malignancy that may be applicable to the broader PEComa family.

Comprehensive Insights Into Renal Perivascular Epithelioid Cell Neoplasms: From Molecular Mechanisms to Clinical Practice

Comprehensive Insights Into Renal Perivascular Epithelioid Cell Neoplasms: From Molecular Mechanisms to Clinical Practice

FK228 suppress the growth of human malignant pleural mesothelioma tumor independent to epithelioid or non-epithelioid histology

Human malignant pleural mesothelioma (hMPM) is an aggressive, rare disease with a poor prognosis. Histologically, MPM is categorized into epithelioid, biphasic, and sarcomatoid subtypes, with the epithelioid subtype generally displaying a better response to treatment. Conversely, effective therapies for the non-epithelioid subtypes are limited. This study aimed to investigate the potential role of FK228, a histone deacetylase inhibitor, in the suppression of hMPM tumor growth. We conducted a comprehensive analysis of the histological and molecular characteristics of two MPM cell lines, CRL-5820 (epithelioid) and CRL-5946 (non-epithelioid). CRL-5946 cells and non-epithelioid patient-derived xenografted mice exhibited heightened growth rates compared to those with epithelioid MPM. Both CRL-5946 cells and non-epithelioid mice displayed a poor response to cisplatin. However, FK228 markedly inhibited the growth of both epithelioid and non-epithelioid tumor cells in vitro and in vivo. Cell cycle analysis revealed FK228-induced G1/S and mitotic arrest in MPM cells. Caspase inhibitor experiments demonstrated that FK228-triggered apoptosis occurred via a caspase-dependent pathway in CRL-5946 but not in CRL-5820 cells. Additionally, a cytokine array analysis showed that FK228 reduced the release of growth factors, including platelet-derived and vascular endothelial growth factors, specifically in CRL-5946 cells. These results indicate that FK228 exhibits therapeutic potential in MPM by inducing cytotoxicity and modulating the tumor microenvironment, potentially benefiting both epithelioid and non-epithelioid subtypes.

Micronodular thymoma with lymphoid stroma: As benign as it sounds.

Micronodular thymoma (MNT) is a rare subtype of thymoma (reported incidence is approximately 1-5%). We report a case received as a core biopsy from the "right lung mass" of a 31-year-old female. CT scan showed an 8.1 cm large well-defined mass lesion in the right middle lobe, causing indentation and mild compression of the right atrium. Microscopically, the biopsy showed a thymic neoplasm comprised of multiple discrete and coalescing nodules of bland epithelioid tumor cells separated by an epithelial cell-free lymphocyte-rich stroma. On immunohistochemistry, cytokeratin highlighted the thymic epithelial cells. The lymphoid cells showed a naive T-cell phenotype (TdT+ CD 3+). It is worthwhile recognizing this rare variant of thymoma as almost all the patients present with localized low stage disease with rare/no reports of recurrences or distant metastases.

PEC-PRO: A new prognostic score from a series of 87 patients with localized perivascular epithelioid cell neoplasms (PEComas) treated with curative intent.

Perivascular epithelioid cell neoplasms (PEComas) encompass a heterogeneous family of mesenchymal tumors. Previously described clinicopathologic features aimed at distinguishing benign from malignant variants but lacked prognostic value. This retrospective analysis examined clinicopathologic data from patients who had localized PEComa across French Sarcoma Network centers. The authors analyzed 12 clinicopathologic features in a Cox proportional hazard framework to derive a multivariate prognostic risk model for event-free survival (EFS). They built the PEComa prognostic score (PEC-PRO), in which scores ranged from 0 to 5, based on the coefficients of the multivariate model. Three groups were identified: low risk (score=0), intermediate risk (score=1), and high risk (score≥2). Analyzing 87 patients who had a median 46-month follow-up (interquartile range, 20-74 months), the median EFS was 96.5 months (95% confidence interval [CI], 47.1 months to not applicable), with 2-year and 5-year EFS rates of 64.7% and 58%, respectively. The median overall survival was unreached, with 2-year and 5-year overall survival rates of 82.3% and 69.3%, respectively. The simplified Folpe classification did not correlate with EFS. Multivariate analysis identified three factors affecting EFS: positive surgical margins (hazard ratio [HR], 5.17; 95% CI, 1.65-16.24; p=.008), necrosis (HR, 3.94; 95% CI, 1.16-13.43; p=.030), and male sex (HR, 3.13; 95% CI, 1.19-8.27; p=0.023). Four variables were retained in the prognostic model. Patients with low-risk PEC-PRO scores had a 2-year EFS rate of 93.7% (95% CI, 83.8%-100.0%), those with intermediate-risk PEC-PRO scores had a 2-year EFS rate of 67.4% (95% CI, 53.9%-80.9%), and those with high-risk PEC-PRO scores had a 2-year EFS rate of 2.3% (95% CI, 0.0%-18.3%). The PEC-PRO score reliably predicts the risk of postoperative recurrence in patients with localized PEComa. It has the potential to improve follow-up strategies but requires validation in a prospective trial.

Evaluation of TRIM63 RNA in situ hybridization (RNA-ISH) as a potential biomarker for alveolar soft-part sarcoma (ASPS)

Alveolar soft-part sarcoma (ASPS) is a rare soft tissue tumor with a broad morphologic differential diagnosis. While histology and immunohistochemistry can be suggestive, diagnosis often requires exclusion of other entities followed by confirmatory molecular analysis for its characteristic ASPSCR1-TFE3 fusion. Current stain-based biomarkers (such as immunohistochemistry for cathepsin K and TFE3) show relatively high sensitivity but may lack specificity, often showing staining in multiple other entities under diagnostic consideration. Given the discovery of RNA in situ hybridization (RNA-ISH) for TRIM63 as a sensitive and specific marker of MiTF-family aberration renal cell carcinomas, we sought to evaluate its utility in the workup of ASPS. TRIM63 RNA-ISH demonstrated high levels (H-score greater than 200) of expression in 19/20 (95%) cases of ASPS (average H-score 330) and was weak or negative in cases of paraganglioma, clear cell sarcoma, rhabdomyosarcoma, malignant epithelioid hemangioendothelioma, as well as hepatocellular and adrenal cortical carcinomas. Staining was also identified in tumors with known subsets characterized by TFE3 alterations such as perivascular epithelioid cell neoplasm (PEComa, average H-score 228), while tumors known to exhibit overexpression of TFE3 protein without cytogenetic alterations, such as melanoma and granular cell tumor, generally showed less TRIM63 ISH staining (average H-scores 147 and 96, respectively). Quantitative assessment of TRIM63 staining by RNA-ISH is potentially a helpful biomarker for tumors with molecular TFE3 alterations such as ASPS.

Systematic analysis of perivascular epithelioid cell neoplasms in the female reproductive tract: a comprehensive review.

Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal lesions, with gynecological PEComas accounting for just over a quarter of cases. Limited reports exist on gynecological PEComa, primarily treated with surgery; adjuvant therapy is considered in high-risk cases. This systematic review aims to summarize the origin and clinical, pathological and molecular characteristics of uterine PEComa, focusing on treatment options for gynecological PEComa. A comprehensive PubMed review of gynecological PEComa reports was conducted. A detailed examination of the literature ensured a thorough understanding. Gynecological PEComa diagnosis relies on histology and immunology. Despite therapy controversies, surgery remains the mainstay. Adjuvant therapy efficacy in high-risk cases is uncertain. mTOR inhibitors are the first line; alternative treatments, including angiogenesis and aromatase inhibitors, should be considered.

Epithelioid angiomyolipoma of the liver in a patient with Li-Fraumeni syndrome: a case report

BackgroundEpithelioid angiomyolipoma (EAML) is a rare variant of angiomyolipoma that predominantly consists of epithelioid cells and belongs to the perivascular epithelioid cell neoplasm (PEComa) family. The majority of EAMLs arise in the kidneys, and primary hepatic EAML appears to be much less common than renal EAML. Most PEComas arise sporadically, but may be associated with tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder characterized by germline mutations in the TSC1 or TSC2 genes. However, PEComas have previously been reported in five patients with Li-Fraumeni syndrome (LFS), which is an inherited cancer susceptibility disorder resulting from germline mutations in the TP53 tumor suppressor gene.Case presentationWe report a 49-year-old female patient with hepatic EAML and pancreatic cancer. Because she had previously been diagnosed with bilateral breast cancer at the age of 30, we performed a comprehensive genetic analysis to identify genetic alterations associated with any cancer predisposition syndrome. Whole-exome sequencing of a blood sample identified a heterozygous germline variant of TP53 (NM_000546.5):c.708C>A, and targeted next-generation sequencing of liver EAML and pancreatic cancer tissue samples demonstrated the same TP53 (NM_000546.5):c.708C>A variant in both. This, plus the patient’s history of early-onset breast cancer, met the 2015 version of the Chompret criteria for diagnosis of LFS.ConclusionsThere have been very few case reports regarding the presence of PEComa in LFS, and to the best of our knowledge, this is the first report of EAML of the liver in a patient with LFS.

Bladder perivascular epithelioid cell neoplasm: Review on clinical features of this rare tumor.

Perivascular epithelioid cell neoplasm (PEComa) is a rare mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells. They can arise in various localizations such as the bladder. A total of 36 case reports regarding bladder PEComa have been described in the literature. Eleven reviews regarding this tumor have been published in literature so far primarily focusing on anatomic pathology. Through these reviews, it is known that in bladder PEComa, the melanocytic marker Human Melanoma Black-45 is expressed in 100% of cases whereas variable expression can be seen in multiple other melanocytic and myoid markers such as smooth muscle actin, Melan-A, CD117, S100, CD31, and CD34. Since current reviews mainly emphasize anatomic pathology, we perform a review focusing on the clinical aspects of PEComa at the level of the clinician. A manual electronic search of the PubMed/Medline and Web of Science Core Collection databases was conducted. Search was done on (perivascular epithelioid cell neoplasms [MeSH terms]) AND (Bladder). All case reports and reviews were encompassed until March 15, 2023, to identify studies that assessed bladder PEComa. The age of presentation is relatively low with a median age of 37 years. There is a female predominance with a female/male ratio of 1.5. The tumor shows no preference in anatomical localization within the bladder. Even involvement of the bladder neck, proximal urethra, and distal ureter has been described. The clinical presentation consists in the majority of patients of symptoms related to the urinary tract such as hematuria, dysuria, passage of urine sediment, frequency, and urgency. Other symptoms include abdominal discomfort and dysmenorrhea. In clinical examination, an abdominal mass can be found based on the size and location of the tumor. Further examination usually encompasses cystoscopy due to the hematuria and radiological investigations such as ultrasound (US), computed tomography, and magnetic resonance imaging. These radiological investigations reveal a heterogeneous solid mass with clear borders. In our center, we performed a transvaginal US additionally in a patient with bladder PEComa, which was the only investigation in our patient that concluded the mass was located in the Retzius space. For treatment, transurethral resection of the bladder tumor and partial cystectomy were both described in equal numbers. The choice of treatment depends on the localization and size of the tumor. Follow-up consists of imaging, but clear guidelines on this matter are lacking. Bladder PEComa is a rare condition and usually presents itself with nonspecific symptoms. Radiological investigations will reveal the tumor, but the final diagnosis is based on cytological and immunohistochemical features. Since bladder PEComa is an entity with uncertain malignant potential, it is important to include this entity in the differential diagnosis when a patient presents with lower abdominal discomfort and lower urinary tract symptoms in combination with a mass in the pelvic region.

Sclerosing Perivascular epithelioid cell neoplasms (PEComa), a rare variant in a unique family of tumors

Abstract Introduction/Objective Perivascular epithelioid cell neoplasms (PEComas) are a rare group of neoplasms that characteristically show both smooth muscle and melanocytic differentiation. The most common tumor in this family is renal angiomyolipoma but may occur in various sites. Sclerosing PEComa (S-PEComa) is an extremely rare variant. its only reported in females and it is usually an incidental finding in the retroperitoneum, in close proximity to the kidney. Methods/Case Report . We present a 52-year-old female, who had a chest CT scan for worsening cough. An - 4 cm exophytic renal mass in the left renal upper pole was found. Patient underwent left partial nephrectomy. Grossly the specimen consisted of 2.5 cm well-circumscribed, white tan mass, abutting the renal capsule, and extending into perinephric adipose tissue. Histology revealed uniform bland epithelioid cells with palely eosinophilic cytoplasm and round nuclei embedded in abundant densely sclerotic stroma. No fat was identified. Immunohistochemistry showed the tumor to be positive for desmin, HMB-45 and SMA with focal staining for AE1/AE3 and negative staining for EMA, cam 5.2, CD 117, calretinin, CD 34, S-100, PAX 8, and Melan A, which confirming the diagnosis of S-PEComa. Results (if a Case Study enter NA) NA Conclusion PEComas, excluding the epithelioid variant, usually has a benign course. In the 13 cases previously reported S-PEComa, 2 patients had metastasis. Our patient, 3-month post-op, has no evidence of disease, but close follow up still warranted.

A rare case of poorly-differentiated endometrial carcinoma in a female-to-male transgender man on testosterone therapy

Abstract Introduction/Objective Testosterone is commonly used as gender-affirming therapy for transmasculine individuals. The effects of testosterone therapy on endometrial tissue are complex, with some experiencing atrophy, and others with abnormal uterine bleeding (AUB). Endometrial carcinomas in transgender men are rarely reported in the literature. Here we present a case of poorly-differentiated endometrial carcinoma in a transgender man on testosterone. Methods/Case Report A 56 year-old female-to-male transgender man who had been on testosterone and finasteride therapy since 2015 developed vaginal discharge in 2022. No history of abnormal pap smears was noted. The patient’s pelvic ultrasound that was subsequently obtained after presenting with the vaginal discharge showed a thickened endometrium of 4 cm thickness. PET-CT revealed hypermetabolic activity corresponding to the endometrial lining of the uterus. Endometrial biopsy was notable for poorly differentiated carcinoma with retained expression of the mismatch repair proteins by immunohistochemical stains. The patient underwent hysterectomy with bilateral salpingo-oophorectomy. Grossly, there was a 9.5 cm necrotic mass occupying the entire endometrial cavity, extending >50% into myometrium thickness and extending into the lower uterine segment, without cervical involvement. Background endometrium was inactive/atrophic. Microscopic examination of the tumor showed sheets of epithelioid tumor cells with extensive necrosis, without any glandular pattern. On immunohistochemical stains, the tumor cells were positive for pankeratin and patchy staining for keratin 7 and keratin 20, without expression of PAX8, estrogen receptor, progesterone receptor or androgen receptor. Results (if a Case Study enter NA) N/A Conclusion Gender-affirming testosterone is a common long-term treatment for transgender men. There is limited understanding of the long-term effects of testosterone therapy on endometrial pathology, particularly regarding the potential for developing malignancy. Positive staining for androgen receptor has been previously reported in endometrial malignancies, and therefore, studies on the potential effects of testosterone therapy on endometrial malignancies is warranted. This case demonstrates the importance of continued gynecologic care in female-to-male transgender individuals who have not undergone previous gender affirming gynecologic surgery.

Malignant Gastrointestinal Neuroectodermal Tumor: A Case Report and Literature Review

Introduction: The gastrointestinal neuroectodermal tumor (GNET) is a rare mesenchymal tumor mainly arising in the gastrointestinal tract. Case Presentation: Herein, we describe a case of GNET that had been previously diagnosed as metastatic primitive neuroectodermal tumor (PNET) to the lung and liver and received 30 cycles of adjuvant chemotherapy. The physical exam showed a palpable mass in the lower right quadrant of the abdomen. The tumor mass was composed of diffuse sheets of epithelioid tumor cells, in which osteoclast-like giant cells scattered unevenly. Immunohistochemically, the tumor cells were diffusely positive for SOX10, CD99, and CD56, patchy positive for pan-CK, and negative for desmin, HMB-45, Melan-A, and chromogranin. Conclusions: Consistent with previous studies that reported a secondary GNET following chemotherapy, we assume that the chemotherapy might trigger the tumorigenesis of GNET in this case.

Comparison of 18F-FDG and 68Ga-FAPI PET/CT in a Patient With Hepatic Perivascular Epithelioid Cell Neoplasm.

The prevalence of hepatic perivascular epithelioid cell neoplasm (PEComa) is extremely low, and imaging diagnosis is very difficult. We presented 18F-FDG and 68Ga-FAPI PET/CT findings in a 58-year-old woman with pathologically confirmed hepatic PEComa. The tumor showed intense 68Ga-FAPI uptake but only mild 18F-FDG activity on PET/CT studies. This case suggested that 68Ga-FAPI PET/CT might be a useful tool for evaluation of hepatic PEComa with remarkable tumor-to-liver ratios.

MesoGraph: Automatic profiling of mesothelioma subtypes from histological images

Mesothelioma is classified into three histological subtypes, epithelioid, sarcomatoid, and biphasic, according to the relative proportions of epithelioid and sarcomatoid tumor cells present. Current guidelines recommend that the sarcomatoid component of each mesothelioma is quantified, as a higher percentage of sarcomatoid pattern in biphasic mesothelioma shows poorer prognosis. In this work, we develop a dual-task graph neural network (GNN) architecture with ranking loss to learn a model capable of scoring regions of tissue down to cellular resolution. This allows quantitative profiling of a tumor sample according to the aggregate sarcomatoid association score. Tissue is represented by a cell graph with both cell-level morphological and regional features. We use an external multicentric test set from Mesobank, on which we demonstrate the predictive performance of our model. We additionally validate our model predictions through an analysis of the typical morphological features of cells according to their predicted score.

EP29.08: Anamnestic and ultrasound findings of uterine perivascular epithelioid cell neoplasms

EP29.08: Anamnestic and ultrasound findings of uterine perivascular epithelioid cell neoplasms