Malignant uterine perivascular epithelioid cell tumor: histopathologic and immunohistochemical characterization of a rare tumor in a post-menopausal woman

Background: Perivascular epithelioid cell tumors (PEComas) are rare, mesenchymal neoplasms composed of epithelioid cells exhibiting myogenic and melanocytic differentiation. The uterus is an infrequent site of involvement. The most common histopathologic mimics include leiomyosarcoma, endometrial stromal sarcoma, undifferentiated uterine sarcoma, and malignant melanoma. Rendering an accurate histopathologic diagnosis is essential, owing to the prognostic and therapeutic implications. Case: A 65-years-old post-menopausal woman presented with post-menopausal bleeding, abdominal pain, and heaviness for the last four months. Ultrasound abdomen revealed a large uterine mass replacing the endometrial cavity. She underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. Result: Microscopically, a circumscribed tumor with tumor cells arranged in sheets and interlacing fascicles, with interspersed fine capillary network, was seen. The individual tumor cells were epithelioid to spindle with moderate pleomorphism, round nuclei, vesicular chromatin, prominent macronucleoli, and moderate cytoplasm. Mitosis was 2-3/50 HPFs. On immunohistochemistry, tumor cells were positive for HMB-45, Melan-A, and smooth muscle actin and were negative for h-caldesmon, TFE3, S-100, CD10, and pan-cytokeratin. Based on the histopathologic and immunohistochemical features, a final diagnosis of malignant uterine PEComa was rendered. Conclusions: This index report describes the characteristic histopathologic and immunohistochemical features of malignant uterine PEComa and highlights the salient features that distinguish it from other commonly encountered histopathologic mimics.     

Malignant perivascular epithelioid cell tumor of the retroperitoneum

Perivascular epithelioid cell tumors (PEComas) are a rare type of mesenchymal neoplasms characterized by a proliferation of perivascular cells with an epithelioid phenotype and expression of myo-melanocytic markers. The majority of PEComas seem to be benign and usually their prognosis is good. Malignant cases are extremely rare, exhibiting a malignant course with local recurrences and distant metastases. We herein report a case of a malignant PEComa arising in the retroperitoneum. The patient was a 55-year-old woman experiencing abdominal discomfort for approximately one month. Ultrasound and computer tomography (CT) scans of the abdomen revealed a solid mass arising from the retroperitoneum. Microscopically, the tumor was composed of epithelioid cells mixed with spindled cells. The nucleus had significant atypia, and the mitoses were obvious. The focal intravascular tumor embolus was visible. Immunohistochemically, the epithelioid tumor cells were positive for HMB45 and Melan-A, and the spindled tumor celLs were positive for SMA and desmin. Seven months after a surgical resection, an ultrasound revealed liver metastases. In conclusion, the malignant PEComas of the retroperitoneum is a very rare neoplasm with unique morphological and immunohistochemical characteristics. It should be differentiated from other epithelioid cell tumors of the retroperitoneum.     

Perivascular epithelioid cell tumor of the pancreas: case report and literature review

Neoplasms with perivascular epithelioid cell differentiation (PEComas) of the pancreas are rare, and only 22 cases have been reported globally. Therefore, clinician and pathologist knowledge of this tumor’s biologic behavior and molecular genetics has been limited. A 40-year-old female patient presented with a space-occupying mass in the pancreas found by abdominal B-mode ultrasonography upon physical examination. Laparoscopic resection of the pancreatic body and tail was performed, and a cystic-solid tumor of about 2 × 2 cm was identified. PEComa is a type of mesenchymal tumor with uncertain biologic behavior, more frequently found in females. PEComa features a unique histomorphology and immunophenotype. We summarize the characteristics and research progress of the pancreatic PEComa, which will be convenient for physicians and pathologists to fully understand the disease to avoid misdiagnosis and to provide a reference for treatment and prognosis.     

Malignant perivascular epithelioid cell tumor of the colon: report of a case with molecular analysis

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm, and malignant cases are extremely rare. A case of malignant PEComa arising in the colon is described herein. The patient was a 43-year-old Japanese woman without a history of tuberous sclerosis complex. The tumor occurred in the abdominal cavity attached to the serosal side of the descending colon. Histologically, the tumor consisted of sheets or closely packed nests of epithelioid cells with clear or eosinophilic cytoplasms. The tumor cells were positive for HMB-45 but negative for S-100 protein and cytokeratins by immunohistochemical staining. Ki-67 labeling index was 2.9%. Peritoneal dissemination of tumor occurred at 20 months and the patient died of tumor at 38 months after the initial operation. This was considered to be a case of malignant PEComa, based on the histological and clinical features. Tumor cells showed overexpression of cyclin D1 but lacked the loss of heterozygosity of the TSC1 and TSC2 genes. The result suggests that the overexpression of cyclin D1 may play an important role in the tumorigenesis of PEComa. Because PEComas can behave in an aggressive manner, careful follow up is warranted.     

Malignant perivascular epithelioid cell tumor (PEComa) of cervix with TFE3 gene rearrangement: a case report

In this study, we reported the first PEComa arising within the cervix with TFE3 gene rearrangement and aggressive biological behavior. Morphologically, the tumor showed infiltrative growth into the surrounding parenchyma. The majority of tumor cells were arrayed in sheets, alveolar structures, or nests separated by delicate fibrovascular septa. There was marked intratumoral hemorrhage, necrosis, and stromal calcifications. The tumor cells had abundant clear cytoplasm, focally containing finely granular dark brown pigment, morphologically considered to be melanin. Immunohistochemically, the tumor cells demonstrated moderately (2+) or strongly (3+) positive staining for TFE3, HMB45, and Melan A but negative for CKpan, SMA, S100, PAX8, and PAX2. The presence of Ki-67 protein demonstrated a moderate proliferation rate, with a few Ki-67-positive nuclei. Using a recently developed TFE3 split FISH assay, the presence of TFE3 rearrangement was demonstrated. All these clinicopathologic features are suggestive of TFE3-rearranged PEComas of the cervix. Our results both expand the known characteristics of primary cervix PEComas and add to the data regarding TFE3 rearrangement-associated PEComas.     

Malignant perivascular epithelioid cell tumor of the kidney with rare pulmonary and ileum metastases

Aims: To report one case of malignant perivascular epithelioid cell tumor (PEComa) of the kidney with rare pulmonary and ileum metastases and analyze its clinicopathological features. Methods: We analyzed the clinicopathological features of one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Immunohistochemistry staining was performed. Results: The patient was a 48-year-old man with a renal mass approximately 14 cm × 11 cm × 8 cm in size. Microscopically, the tumor was mainly composed of polygonal epithelioid cells with dense eosinophilic cytoplasm and round nuclei with small nucleoli. Focal tumor cells showed pleomorphism with multinucleated giant cells and prominent nucleoli. The tumor cells nests were surrounded by thick-walled irregular blood vessels. Focal fat cells were found within the tumor. Hemorrhage and coagulative necrosis were also present. The tumor cells were positive for vimentin, HMB45, and Melan-A, and focally positive for SMA and S-100 protein. After 5 years and 5.6 years of nephrectomy, the tumor metastasized to the right lung and ileum, respectively. Conclusion: We first reported one case of malignant PEComa of the kidney with pulmonary and ileum metastases. Metastatic PEComa of the lung and ileum should differentiate from primary carcinoma, metastatic carcinoma, malignant melanoma, and gastrointestinal stromal tumor.     

Fine‐needle aspiration cytology of epithelioid malignant peripheral nerve sheath tumor: A case report and review of the literature

The epithelioid variant of malignant peripheral nerve sheath tumor (eMPNST) is an extremely rare soft tissue neoplasm comprising less than 5% of all MPNSTs. It is distinguished cytomorphologically from a conventional MPNST by the presence of polymorphous round epithelioid cells arranged in loose clusters with or without spindled tumor cells. These features pose a diagnostic challenge because the differential diagnosis involves a variety of mesenchymal and non‐mesenchymal tumors including epithelioid sarcoma, sclerosing epithelioid fibrosarcoma, malignant rhabdoid tumor, chordoma, metastatic carcinomas, and melanoma. Thus, it may become imperative to perform immunochemical stains on cell blocks of FNA aspirates to arrive at definitive diagnosis. Reports describing the cytologic features of eMPNST are rare. Herein, we report a case of eMPNST with focus on cytomorphologic and cytoimmunochemical features and differential diagnosis. Diagn. Cytopathol. 2016;44:226–231. © 2015 Wiley Periodicals, Inc.     

硬化性上皮样纤维肉瘤临床病理特点及其诊断

目的探讨硬化性上皮样纤维肉瘤(sclerosing epithelioid fibrosarcoma,SEF)的临床病理学特征、诊断及鉴别诊断。方法对1例SEF进行组织学观察和免疫组化标记,同时复习相关文献。结果SEF主要以上皮样细胞伴大量胶原纤维为特征,瘤细胞胞质透亮,似上皮细胞,排列呈条索状,间质中大量胶原纤维发生透明变性,形成硬化性基质。肿瘤细胞vimentin阳性,cytokeratin和actin阴性。结论SEF是一种较为罕见的软组织肿瘤,应注意与一些具有上皮样形态和硬化性间质的肿瘤相鉴别。     

Malignant rhabdoid tumor of the liver: case report and literature review

A case of malignant rhabdoid tumor (MRT) occurring as a primary hepatic neoplasm in a 12-month-old Japanese female infant is presented. The patient had a slight fever for 2 weeks and presented with a palpable mass in her left hypochondrial region. After admission, the hepatic artery was embolized due to intra-abdominal hemorrhage arising from the tumor. The patient received chemotherapy with cisplatin, cyclophosphamide and adriacin. Despite treatment, the patient developed dyspnea, pancytopenia and disseminated intravascular coagulation. Rupture of the tumor resulted in death within 3 weeks. A limited abdominal autopsy revealed that the liver weighed 1240 g and was occupied by multiple hemorrhagic and/or necrotic tumor nodules. Histologically, neoplastic cells had an abundant eosinophilic cytoplasm containing paranuclear inclusions, and vesicular nuclei with a centrally located prominent nucleolus. Ultrastructurally, the cytoplasmic inclusions were composed of whorled filaments measuring 10 nm. Immunohistochemically, almost all of the neoplastic cells were positive for vimentin and cytokeratins (CK) 8 and 18, some were positive for CK 7 and 19, while none were positive for CK 1, 10, 13-17 and 20. The tumor cells did not express desmin, myoglobin, and alpha-fetoprotein. We found 18 cases of MRT of the liver published in English language literature and then, adding the present case, we summarized the 19 cases. Hepatic MRT is an uncommon neoplasm. However, it should be considered in the differential diagnosis of an aggressive liver neoplasm in childhood.     

Epithelioid trophoblastic tumor of the uterus: cytological and immunohistochemical observation of a case

Epithelioid trophoblastic tumor (ETT) is a new entity of trophoblastic tumor and 14 such cases were reported by Shih and Kurman in 1998. However, only three subsequent cases supporting ETT have been reported. Recently, we experienced a case of ETT in a 37-year-old woman whose preoperative endometrial brushings showed atypical mononucleate giant cells and who underwent hysterectomy with the diagnosis of a uterine fibroid. The specimens revealed a 2.5 x 3.0 cm yellow-tan intramural nodule located in the lower uterine segment, which was composed of a neoplastic proliferation of intermediate trophoblasts in epithelioid arrangements. Immunohistochemically, the tumor cells were diffusely positive for cytokeratin and inhibin-alpha, and focally positive for human chorionic gonadotropin and human placental lactogen. She presented an uneventful clinical course as of September 2001.     

Primary perivascular epithelioid cell tumor in the rectum: A case report and review of the literature

Perivascular epithelioid cell tumor (PEComa) is a rare collection of tumors arising in a wide array of anatomic locations. It is characterized by the presence of a peculiar population of myomelanocytic marker-positive perivascular epithelioid cells, and is commonly detected in the uterus. The colorectal area is an uncommon site for primary PEComa. In this study, we describe a 17-year-old patient presenting with a rectal polyp. Histologically, the tumor consisted of sheets of round to polygonal epithelioid cells with clear and granular cytoplasm, and a prominent capillary network. Some of the tumor cells were positive for Fontana-Masson staining. Immunohistochemically, the tumor cells were positive for HMB-45, and were negative for cytokeratin, vimentin, S-100 protein, actin, desmin, EMA, CD34, and c-kit. After finding melanosomes or premelanosomes at the ultrastructural level, the diagnosis of PEComa was made. Although PEComa arising within the intestinal tract is unusual and clinically unexpected, PEComa should be considered in the differential diagnosis of rectal polypoid lesions.     

Perivascular epithelioid cell tumor (PEComa) of the pancreas: Immunoelectron microscopy and review of the literature

A perivascular epithelioid tumor (PEComa) is a rare tumor probably arising from the perivascular epithelioid cells. Only three cases of pancreatic PEComa have been reported in the English-language literature. The present report describes an extremely rare case of pancreatic PEComa. A 47-year-old Japanese woman complained of lower abdominal pain and a well-demarcated solid tumor was found in the pancreatic head. There was no history of tuberous sclerosis complexes. Pylorus-preserving pancreaticoduodenectomy was thus performed. There was a well-demarcated, solid tumor measuring 17 mm in the pancreatic head. The tumor was composed of a diffuse proliferation of epithelioid tumor cells with many blood vessels but no adipose tissue. The tumor cells expressed HMB45 and α-smooth muscle actin. Ultrastructurally, the tumor cells possessed many membrane-bound granules that were positive for HMB45 on immunoelectron microscopy. The results of immunoelectron microscopy show that some PEComas possess not only typical melanosomes or premelanosomes but also aberrant melanosomes.     

Epithelioid trophoblastic tumor after induced abortion with previous broad choriocarcinoma: a case report and review of literature

Epithelioid trophoblastic tumor (ETT) is a rare trophoblastic tumor originating from chorionic-type intermediate trophoblasts (ITs). It is usually associated with a prior gestational event. We present a 44-year-old woman who had unusual pregnancy related history. The patient received her second spontaneous abortion at the age of 25 years and had suffered from choriocarcinoma in left board ligament at the age of 29 years. She admitted no more treatment after 3 courses of multiagent chemotherapy when serum β-hCG returned to normal. Then she had Full-term delivery, induced abortion at the ages of 32, 33 years. The patient had high serum levels of beta-human chorionic gonadotropin (6587 IU/L). Microscopically, the tumor was composed of mainly mononuclear tumor cells, grew in cords, nests, and sheets within which were aggregates of hyaline material. Most were with distinct cell borders, eosinophilic cytoplasm. Immunohistochemical staining revealed strong diffuse reactivity for cytokeratins (AE1/AE3, CK18), P63, focal reactivity for beta-human chorionic gonadotropin, human placental lactogen, and inhibin-alpha. The Ki-67 index was 77%. The histological and immunohistochemical features were characteristic of epithelioid trophoblastic tumor. This is the first reported case of these two gestational trophoblastic tumor happened on one person with the intervening normal pregnancy.     

Sclerosing variant of perivascular epithelioid cell tumor in the female genital organs

Perivascular epithelioid cell tumor (PEComas), other than angiomyolipoma, clear cell 'sugar' tumor of the lung, and lymphangioleiomyomatosis, is an uncommon mesenchymal neoplasm that arises in the soft tissue and visceral organs. We report herein two cases of sclerosing PEComa; a distinctive variant of PEComa, which is characterized by extensive stromal hyalinization, occurring in the uterus and broad ligament. The patients were 34- and 51-year-old females with no family history of tuberous sclerosis complex. Macroscopically, the tumors had white to gray cut surfaces and were microscopically composed of predominantly spindle- to polygon-shaped cells with clear to slightly eosinophilic cytoplasm and pleomorphic nuclei focally arranged in a perivascular pattern, accompanied by marked stromal hyalinization. These tumor cells were immunohistochemically positive for HMB45 and α-smooth muscle actin. Although this variant of PEComa is very rare, this entity should be considered as a potential primary neoplasm of the female genital organs.     

Malignant peripheral nerve sheath tumor with prominent intracytoplasmic vacuolation: Report of a case

A case of malignant peripheral nerve sheath tumor with uncommon features is reported. A mass was noted in the left thigh of a 16 year old man. Histologically, most areas of the tumor exhibited the typical appearance of malignant peripheral nerve sheath tumor, but some tumor cells had rounded nuclei and cytoplasm, resembling an epithelioid pattern. It was noted that some rounded tumor cells showed prominent intracytoplasmic vacuolation. Immunohistochemically, almost all of the tumor cells, including the rounded and vacuolated ones, were positive for S-100 protein and vimentin. Electron microscopic study revealed well-developed cytoplasmic processes, intracytoplasmic intermediate-sized filaments, basement lamina formation and extracellular long-spacing collagens. These findings were compatible with those of Schwann cell differentiation. Moreover, ultrastructurally, the vacuolated spaces contained a few granular materials and were derived from the dilatation of the rough endoplasmic reticulum. It is speculated that intracytoplasmic vacuolation in malignant peripheral nerve sheath tumor would be caused by degeneration of the tumor cells.     

Perivascular epithelioid cell tumor of the uterine cervix identified on a conventional cervical smear

Perivascular epithelioid cell tumors (PEComas) most frequently involve the uterus, particularly the uterine corpus and very occasionally the cervix. One case of PEComa identified using a conventional cervical smear has previously been documented. Herein, we present the second such case. The patient was a 51‐year‐old woman with abnormal genital tract bleeding. Samples collected for conventional cervical smears were submitted for cytopathological examination, which revealed discohesive monotonous tumor cells showing epithelioid morphology, ample cytoplasm that was pale to weakly eosinophilic, and mildly enlarged nuclei. The cytopathological features were well correlated with histopathological findings. Upon immunohistochemistry, the tumor cells were positive for both melanocytic and smooth muscle markers. Based on these findings, PEComa was diagnosed. Subsequently, a total hysterectomy with bilateral salpingo‐oophorectomy was performed, revealing that the tumor (28 × 22 × 12 mm) was located at the superficial part of the endocervix. We propose that the cytopathological findings described herein can guide the diagnosis of PEComa, even though this tumor is rare. Diagn. Cytopathol. 2015;43:1011–1016. © 2015 Wiley Periodicals, Inc.     

Malignant rhabdoid tumor of the vulva: Case report with cytological, immunohistochemical, ultrastructural and DNA ploidy studies and a review of the literature

A case of malignant rhabdoid tumor of the vulva in a 25-year-old female was examined. The patient presented with a subcutaneous nodule in the lefl labium majus. Smears of the material obtained by percutaneus fineneedle asplratlon demonstrated clusters of atypical cells with prominent nucleoli. The tumor measured 6 × 5 × 5 cm and appeared tan to brown on the cut surface and partly cystlc. Pathological findings obtalned from intraoperative frozen tlssue sections had been originally interpreted as rhabdomyosar-coma. Light microscopic examination revealed that polyge nal tumor cells having vesicular nuclei with prominent nucleoli were arranged in sheets and the great majority of the tumor cells contained an eosinophillc globular paranu-clear cytoplasmic Inclusion. Ultrastructurally, this cytoplas-mic inclusion corresponds to whirls of intermediate filaments. Vlmentln immunoreactlvity was detected in both the cytoplasm and cytoplamic inclusion of almost all the tumor cells. No cytokeratin and desmin immunoreactivlty were detected In the tumor cells. The Ki-67 labeling index was 36% and the DNA content of the tumor cells, which was examined by image cytometry, demonstrated diploidy (DNA Index = 0.95).     

Yolk sac tumor of vagina: a case report

Malignant germ-cell tumors (MGCT) are rare tumors of childhood accounting for less than 3% of pediatric malignancies. Yolk sac (endodermal sinus) tumor is one of the malignant germ cell tumor that usually involves the gonads (ovaries and testes). Its occurrence in the vagina is extremely rare. We report a 6-months old girl presented with a vaginal mass diagnosed as a yolk sac tumor. This diagnosis is confirmed by histopathologic examination, immunehistochemical studies as well as elevated serum alpha fetoprotein (AFP).     

肾恶性孤立性纤维性肿瘤1例报道及文献复习

目的 探讨肾脏恶性孤立性纤维性肿瘤的临床病理特征、鉴别诊断及治疗和预后.方法 报道1例肾恶性孤立性纤维性肿瘤的临床病理资料并复习文献.结果 患者男性,56岁.临床主要表现为乏力、出汗、心慌、气短1年,以低血糖原因待查入院.CT示左肾上方及左肾前下方见3个类圆形软组织密度影,与肾分界不清,大小分别为9 cm×8 cm×7 cm、7 cm×7cm×7 cm和4 cm×4 cm ×4 cm.增强后边缘轻度强化,中心不均匀强化.临床、CT检查考虑为左.肾癌.行左肾癌根治术.眼观:左肾上、下极分别见一肿块,切面灰白色,部分区见有坏死,与肾界限不清.镜检:肿瘤由短梭形或卵圆形细胞组成,排列成束状、旋涡状或不规则状.部分区域血管丰富,细胞密集呈血管外皮瘤样结构;部分区域细胞稀疏伴纤维化、黏液变性.肿瘤超过60%的区域内(尤其是肾下极肿块)瘤细胞丰富密集,有异型性,核分裂象多见(>4个/10 HPF),边缘呈浸润性生长,部分区可见出血坏死.免疫表型:肿瘤细胞vimentin、CD34弥漫阳性,CD99、bcl-2阳性,Ki-67增殖指数>20%.病理诊断:左肾恶性孤立性纤维性肿瘤(低度恶性).术后随访24个月情况良好.结论 肾恶性孤立性纤维性肿瘤非常罕见,确诊主要依靠病理形态学及免疫组织化学标记,并应与肾的其他梭形细胞肿瘤进行鉴别.治疗以手术完全切除为主,并注意长期随访.