Hepatic perivascular epithelioid cell tumors:The importance of preoperative diagnosis

Accurate preoperative diagnosis is highly important for the treatment of perivascular epithelioid cell tumors(PEComas)because PEComas are mainly benign tumors and may not require surgical intervention.By analyzing the causes,properties and clinical manifestations of PEComas,we summarize the challenges and solutions in the diagnosis of PEComas.

Perivascular epithelioid cell tumors of the liver misdiagnosed as hepatocellular carcinoma:Three case reports

BACKGROUND Hepatic perivascular epithelioid cell neoplasms(PEComas)are rare.Diagnostic and treatment experience with hepatic PEComa remains insufficient.CASE SUMMARY Three hepatic PEComa cases are reported in this paper:One case of primary malignant hepatic PEComa,one case of benign hepatic PEComa,and one case of hepatic PEComa with an ovarian mature cystic teratoma.During preoperative imaging and pathological assessment of intraoperative frozen samples,patients were diagnosed with hepatocellular carcinoma(HCC),while postoperative pathology and immunohistochemistry subsequently revealed hepatic PEComa.Patients with hepatic PEComa which is misdiagnosed as HCC often require a wider surgical resection.It is easy to mistake them for distant metastases of hepatic PEComa and misdiagnosed as HCC,especially when it’s combined with tumors in other organs.Three patients eventually underwent partial hepatectomy.After 1-4 years of follow-up,none of the patients experienced recurrence or metastases.CONCLUSION A clear preoperative diagnosis of hepatic PEComa can reduce the scope of resection and prevent unnecessary injuries during surgery.

Hepatic perivascular epithelioid cell tumor:Clinicopathological analysis of 26 cases with emphasis on disease management and prognosis

BACKGROUND Perivascular epithelioid cell tumor(PEComa)is an uncommon tumor of mesenchymal origin.Cases of PEComa in the liver are extremely rare.AIM To analyze the clinicopathological features and treatment of hepatic PEComa and to evaluate the prognosis after different treatments.METHODS Clinical and pathological data of 26 patients with hepatic PEComa were collected.All cases were analyzed by immunohistochemistry and clinical follow-up.RESULTS This study included 17 females and 9 males,with a median age of 50 years.Lesions were located in the left hepatic lobe in 13 cases,in the right lobe in 11,and in the caudate lobe in 2.The median tumor diameter was 6.5 cm.Light microscopy revealed that the tumor cells were mainly composed of epithelioid cells.The cytoplasm contained heterogeneous eosinophilic granules.There were thick-walled blood vessels,around which tumor cells were radially arranged.Immunohistochemical analysis of pigment-derived and myogenic markers in PEComas revealed that 25 cases were HMB45(+),23 were Melan-A(+),and 22 SMA(+).TFE3 and Desmin were negative in all cases.All the fluorescence in situ hybridization samples were negative for TFE3 gene break-apart probe.Tumor tissues were collected by extended hepatic lobe resection or simple hepatic tumor resection as the main treatments.Median follow-up was 62.5 mo.None of the patients had metastasis or recurrence,and there were no deaths due to the disease.CONCLUSION Hepatic PEComa highly expresses melanin and smooth muscle markers,and generally exhibits an inert biological behavior.The prognosis after extended hepatic lobe resection and simple hepatic tumor resection is semblable.

Hepatic perivascular epithelioid cell tumor in three patients

Perivascular epithelioid cell tumor （PEComa） is a rare, soft tissue tumor that can occur in various locations. The present report included three patients （one male and two females; age range, 25-51 years） with hepatic PEComas. The collected data included the clinical manifestations, diagnosis, management, treatment, and prognosis. Since it is difficult to diagnose hepatic PEComas by imaging, the patients were diagnosed by tumor tissue examination such as immunohistochemistry, which was positive for HMB-45, Melan-A, and SMA on all slides. The tumor was composed of diverse tissues including smooth muscle, adipose tissue, and thick-walled blood vessels. During the follow-up period, one of the tumors was malignant （double-positive for CD34 and Ki-67） and recurred 3 months after surgery. In addition, malignant hepatic PECo- mas were reviewed in the literature, indicating that the majority of hepatic PEComas are benign, but few hepatic PEComas exhibit malignant behaviors in older female patients （〉50 years of age） with abdominal discomfort and pain, larger tumor size （〉10 cm）, or positive staining for CD34 and Ki-67. In conclusion, there is no effective method to diagnose PEComas. Currently, the diagnosis of PEComas depends on immunohistochemical staining. Tumor resection and close follow-up are the principal methods for the management of PEComas.

A perivascular epithelioid cell tumor of the stomach:An unsuspected diagnosis

Perivascular epithelioid cell tumor(PEComa) is a rare mesenchymal neoplasia and currently well recognized as a distinct entity with characteristic morphological,immunohistochemical and molecular findings.We report a case of PEComa arising in the antrum of a 71-year-old female with melena.The tumor,located predominantly in the submucosa as a well delimited nodule,measured 3.0 cm in diameter and was completely resected,with no evidence of the disease elsewhere.Histologically,it was composed predominantly of eosinophilic epithelioid cells arranged in small nests commonly related to variably sized vessels,with abundant extracellular material,moderate nuclear variation and discrete mitotic activity.No necrosis,angiolymphatic invasion or perineural infil-tration was seen.Tumor cells were uniformly positive for vimentin,smooth muscle actin,desmin and melan A.Although unusual,PEComa should be considered in the differential diagnosis of gastric neoplasia with characteristic epithelioid and oncocytic features and prominent vasculature.

Hepatic perivascular epithelioid cell tumor:A case report

BACKGROUND Perivascular epithelioid cell tumor(PEComa)is a mesenchymal tumor with histologic and immunophenotypic characteristics of perivascular epithelioid cells,has a low incidence,and can involve multiple organs.PEComa originating in the liver is extremely rare,with most cases being benign,and only a few cases are malignant.Good outcomes are achieved with radical surgical resection,but there is no effective treatment for some large tumors and specific locations that are contraindicated for surgery.CASE SUMMARY A 32-year-old woman was admitted to our hospital with a palpable abdominal mass and progressive deterioration since the previous month.An ultrasoundguided percutaneous liver aspiration biopsy was performed.Postoperative pathological immunohistochemical staining was HMB45,Melan-A,and smooth muscle actin positive.Perivascular epithelioid tumor was diagnosed.The tumor was large and could not be completely resected by surgery.Further digital subtraction angiography revealed a rich tumor blood supply,and interventional embolization followed by surgery was recommended.Finally,the patient underwent transarterial embolization(TAE)combined with sorafenib for four cycles.Angiography reexamination indicated no clear vascular staining of the tumor,and the tumor had shrunk.The patient was followed up for a short period of time,achieved a stable condition,and surgery was recommended.CONCLUSION Adjuvant combination treatment with TAE and sorafenib is safe and feasible as it shrinks the tumor preoperatively and facilitates surgery.

Perivascular epithelioid cell tumor of male pelvic cavity:a case report and literature review

Perivascular epithelioid cell tumors （PEComas） are a family of rare mesenchymal neoplasms. The PEComas, composed of epithelioid and spindle cells, have the same cellular and immtmohistocherrtical features but are found in different visceral and soft tissue sites. Here, we report the histological and immunohistochemical features of one case of PEComa restricted in the pelvic visceral peritoneum of a male patient. The patient was treated with radical surgery, and was well and on follow-up visits without tumor recurrence.

TFE3-expressing malignant perivascular epithelioid cell tumor of the mesentery:A case report and review of literature

BACKGROUND Perivascular epithelioid cell tumor(PEComa)is a rare mesenchymal tumor that exhibits an epithelioid and spindle cell morphology.The tumor is characterized by immunoreactivity for melanocytic and myogenic markers but can be misdiagnosed as more common tumors with similar characteristics,including gastrointestinal stroma tumors or leiomyosarcomas.Recently,a subset of PEComas has been reported to harbor a transcription factor binding to TFE3 fusion.Herein,we report a rare case of TFE3-expressing malignant PEComa arising from the mesentery.CASE SUMMARY A 50-year-old woman presented with abdominal discomfort for 3 months.Results of laboratory tests were all within the normal ranges,and the patient had no notable medical history.Magnetic resonance imaging revealed a large tumor on the right side of the pelvic floor,which was originally suspected to be a primary ovarian tumor.However,during surgery,the tumor was revealed to have originated from the mesentery.Histologically,the tumor was composed of bundles of spindle cells and sheets of epithelioid cells.Extensive coagulative necrosis and numerous mitotic figures were observed.Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin,HMB-45,and TFE3 expression.Tumor involvement of the rectal serosa was identified,leading to a final diagnosis of malignant PEComa of the mesentery.Surgical resection was followed by adjuvant chemotherapy.No recurrence or metastasis was observed over a 6-month follow-up period.CONCLUSION Malignant PEComa of the mesentery is extremely rare and should be distinguished from morphological mimics through differential diagnosis and immunohistochemistry.

Pediatric case of colonic perivascular epithelioid cell tumor complicated with intussusception and anal incarceration:A case report

BACKGROUND Perivascular epithelioid cell tumor(PEComa)represents a group of rare mesenchymal tumors.PEComa can occur in many organs but is rare in the colorectum,especially in children.Furthermore,PEComa is a rare cause of intussusception,the telescoping of a segment of the gastrointestinal tract into an adjacent one.We describe a rare case of pediatric PEComa complicated with intussusception and anal incarceration,and conduct a review of the current literature.CASE SUMMARY A 12-year-old girl presented with abdominal pain and abdominal ultrasound suggested intussusception.Endoscopic direct-vision intussusception treatment and colonoscopy was performed.A spherical tumor was discovered in the transverse colon and removed by surgery.Postoperative pathologic analyses revealed that the tumor volume was 5.0 cm×4.5 cm×3.0 cm and the tumor tissue was located in the submucosa of the colon,arranged in an alveolar pattern.The cell morphology was regular,no neoplastic necrosis was observed,and nuclear fission was rare.The immunohistochemical staining results were as follows:Human melanoma black 45(HMB 45)(+),cluster of differentiation 31(CD31)(+),cytokeratin(-),melanoma-associated antigen recognized by T cells(-),smooth muscle actin(-),molleya(-),desmin(-),S-100(-),CD117(-),and Ki67(positive rate in hot spot<5%).Combined with the results of pathology and immunohistochemistry,we diagnosed the tumor as PEComa.Postoperative recovery was good at the 4 mo follow-up.CONCLUSION The diagnosis of PEComa mainly depends on pathology and immunohistochemistry.Radical resection is the preferred treatment method.

Perivascular epithelioid cell tumour of the liver

Perivascular epithelioid cell tumour is not uncommon in the liver but seldom malignant.

Retroperitoneal neoplasm with perivascular epithelioid cell differentiation: A case report and review of literature

The retroperitoneal neoplasm with perivascular epithelioid cell differentiation (PEComa) is an extremely rare pathological entity. In this article, we reported one case of a 45-year-old woman who was admitted to our hospital (The Second People's Hospital of Hefei, China) for retroperitoneal neoplasm with perivascular epithelioid cell differentiation. The B ultrasonic examination showed echopoor in the region of cavitas pelvis. The histologic characteristics and immunohistochemical phenotype both revealed the neoplasm with perivascular epithelioid cell differentiation.

Improving recognition of hepatic perivascular epithelioid cell tumor:Case report and literature review

A 58-year-old man presented with the chief complaint of abdominal bloating and was incidentally found to have a liver tumor.As diagnostic imaging studies could not rule out malignancy,the patient underwent partial resection of segment 3 of the liver.The lesion pathologically showed eosinophilic proliferation,in addition to immunohistochemical positivity for human melanoma black 45 and Melan-A,thereby leading to the diagnosis of a hepatic perivascular epithelioid cell tumor(PEComa).A PEComa arising from the liver is relatively rare.Moreover,the name ‘PEComa' has not yet been widely recognized,and the same disease entity has been called epithelioid angiomyolipoma(EAML),further diminishing the recognition of PEComa.In addition,PEComa imaging findings mimic those of malignant liver tumors,and clinically,this tumor tends to enlarge.Therefore,a PEComa is difficult to diagnose.We conducted a systematic review of PEComa and EAML cases and discuss the results,including findings useful for differentiating perivascular epithelioid cell tumors from malignant liver tumors.

Retroperitoneal perivascular epithelioid cell tumours: A case report and review of literature

BACKGROUND The perivascular epithelioid cell tumour(PEComa)family of tumours mainly includes renal and hepatic angiomyolipomas,pulmonary lymphangioleiomyomatosis and clear cell“sugar”tumour of the lung.Several uncommon tumours with similar morphological and immunophenotypical characteristics arising at a variety of sites(abdominal cavity,digestive tract,retroperitoneum,skin,soft tissue and bones)are also included in the PEComa family and are referred to as PEComas not otherwise specified.CASE SUMMARY We present a 37-year-old female patient who underwent resection of an 8.5 cm×8 cm×4 cm retroperitoneal tumour,which eventually was diagnosed as PEComa of uncertain biological behaviour.Three years after the operation,the patient remains without any evidence of recurrence.A search was performed in the Medline and EMBASE databases for articles published between 1996 and 2018,and we identified 31 articles related to retroperitoneal and perinephric PEComas.We focused on sex,age,maximum dimension,histological and immunohistochemical characteristics of the tumour,follow-up and long-term outcome.Thirty-four retroperitoneal(including the present one)and ten perinephric PEComas were identified,carrying a malignant potential rate of 44%and 60%,respectively.Nearly half of the potentially malignant PEComas presented with or developed metastases during the course of the disease.CONCLUSION Retroperitoneal PEComas are not as indolent as they are supposed to be.Radical surgical resection constitutes the treatment of choice for localized disease,while mammalian target of the rapamycin(mTOR)inhibitors constitute the most promising therapy for disseminated disease.The role of mTOR inhibitors as adjuvant or neoadjuvant therapies needs to be evaluated in the future.

Coincidence between malignant perivascular epithelioid cell tumor arising in the gastric serosa and lung adenocarcinoma

A 4-mo history of both epigastralgia and back pain was presented in a 39-year-old male. Computed tomography showed right lung nodule and abdominal mass attached to the gastric wall, measuring approximately 30 mm and 70 mm in diameter. Since biopsy samples from the lung and abdomen revealed poorly differentiated adenocarcinoma and malignant tumor, clinicians first interpreted the abdominal mass as metastatic carcinoma, and a right lower lobectomy with following resection of the mass was performed. Gross examination of both lesions displayed gray-whitish to yellow-whitish cut surfaces with hemorrhagic and necrotic foci, and the mass attached to the serosa of the lesser curvature on the gastric body. On microscopic examination, the lung tumor was composed of a proliferation of highly atypical epithelial cells having abundant eosinophilic cytoplasm, predominantly arranged in an acinar or solid growth pattern with vessel permeation, while the abdominal tumor consisted of sheets or nests with markedly atypical epithelioid cells having pleomorphic nuclei and abundant eosinophilic to clear cytoplasm focally in a radial perivascular or infiltrative growth pattern. Immunohistochemically, the latter cells were positive for HMB45 or α-smooth muscle actin, but the former ones not. Therefore, we finally made a diagnosis of malignant perivascular epithelioid cell tumor(PEComa) arising in the gastric serosa, combined with primary lung adenocarcinoma. Furthermore, small papillary car-cinoma of the thyroid gland was identified. The current case describes the coincidence of malignant PEComa with other carcinomas, posing a challenge in distinction from metastatic tumor disease.

Pancreatic perivascular epithelioid cell tumor: A case report with clinicopathological features and a literature review

Perivascular epithelioid cell tumor(PEComa) of the pancreas is an unusual tumor deriving from mesenchyma. This paper described a case of pancreatic PEComa, which was initially suspected as neuroendocrine carcinoma by biopsy, and therefore surgical treatment was recommended due to undetermined diagnosis. Examination of the surgical specimen under a microscope showed that the tumor cell's morphology was epithelioid or spindle-shaped, and ranged in a nested pattern. Additionally, these cells had a large extent of acidophilic cytoplasm, no mitotic figures, and expressed HMB-45, melan-p, and smooth muscle actin immunohistochemically. Pathological examination indicated that PEComa originated from the pancreas, but symptoms related to tuberous sclerosis were absent. Since PEComa is extremely rare in the pancreas, it is likely to be ignored in differential diagnosis. In conclusion, our article highlighted the clinicopathological features of PEComa, and we conducted a literature review focusing on PEComa so as to deepen the understanding of this tumor type.

Perivascular epithelioid cell neoplasm of the colon

A 17-year-old female presented with rectal bleeding from an ulcerated sigmoid mass in 1994.Initial pathological evaluation revealed a rare clear cell neoplasm of the colon,possibly originating from kidneys,adrenals,lung or a gynecologic source as a metastatic lesion.Extensive imaging studies were negative,and over the next 15 years,she remained well with no recurrence.The original resected neoplasm was reviewed and reclassified as a perivascular epithelioid cell neoplasm (PEComa).Although the long-term natural history of PEComas requires definition,increased clinical and pathological awareness should lead to increased recognition of an apparently rare type of colonic neoplasm that likely occurs more often than is currently appreciated.

Cutaneous perivascular epithelioid cell tumors:A review on an infrequent neoplasm

"Perivascular epithelioid cutaneous" cell tumors(PEComa) are a family of mesenchymal tumors with shared microscopic and immunohistochemical properties: They exhibit both smooth muscle cell and melanocytic differentiation. Non-neoplastic counterpart of PEComa's cells are unknown, as well as the relationship between extracutaneous PEComa and primary cutaneous ones. We will review the clinical setting, histopathologic features, chromosomal abnormalities, differential diagnosis and treatment options for cutaneous PEComa.

Robotic wedge resection of a rare gastric perivascular epithelioid cell tumor: A case report

BACKGROUND Perivascular epithelioid cell tumor(PEComa) is a rare mesenchymal neoplasm that can arise in many different organs with a broad spectrum of biological behavior, from indolent to aggressive progression. Only ten cases of gastric PEComas have been reported in the English literature, which were treated with endoscopic, laparoscopic, or open resections. Due to its rarity, the optimal surgical management and prognosis of this tumor are still uncertain.CASE SUMMARY We present a case of robotic wedge resection of a 6.5 cm bleeding lesion of the gastric fundus located 3 cm below the esophago-gastric junction in a 55-year-old man. Biopsy revealed a malignant tumor with epithelioid cells focally positive for muscle markers desmin and smooth muscle actin. In addition, histology revealed that the tumor was positive for HMB-45, melan-A(MART-1), microphthalmia transcription factor and negative for pan-cytokeratin AE1/AE3, CD34, p40, DOG-1, CD117(c-kit), S100, CD3, CD79 a, caldesmon and myogenin. These markers suggested the possibility of a PEComa. The patient underwent a diagnostic laparoscopy via the da Vinci? Si? system and robotic wedge resection. Final pathology confirmed a malignant gastric PEComa with negative margins. At his 11-mo follow-up visit, the patient remained disease-free.CONCLUSION Gastric PEComa can be treated with a robotic R0 resection with acceptable postoperative and short-term oncological outcomes.

Single-center Experience in the Diagnosis and Treatment of Hepatic Perivascular Epithelioid Cell Neoplasm

Background and Aims:Perivascular epithelioid cell neo-plasms(PEComas)are a rare type of mesenchymal neo-plasm and their preoperative diagnosis is challenging.In this study,we summarized the experience from a single medical center to study the examinations,clinical presen-tations,and pathological and histological characteristics of PEComas in the liver in order to optimize overall un-derstanding of the diagnosis and treatment of these neo-plasms.Methods:We conducted a retrospective analysis to investigate the clinical and pathological characteristics as well as imaging presentations of 75 patients diagnosed with hepatic PEComa in The First Affiliated Hospital of Zhe-jiang University between April 2010 and April 2020.Re-sults:Among the 75 patients,52 were women,and the median age was 48 years.Most patients had no specific symptoms,and two were admitted to the hospital for a second time owing to relapse.All patients underwent surgi-cal resection.Histologically,38 patients had classical angio-myolipoma(AML)and 37 had epithelioid AML.The PECo-mas were accompanied by positive immunohistochemical expression of HMB45,Melan-A,and smooth muscle actin.Follow-up data were obtained from 47 of the total 75 pa-tients,through October 2020.Two patients had metastasis after surgery.Conclusions:AML is the most common type of hepatic PEComa.There are no specific symptoms of he-patic PEComa,and serological examinations and imaging modalities for accurate preoperative diagnosis are lacking.Epithelioid AML should be considered a tumor of uncertain malignant potential;however,the prognosis of PEComa af-ter resection is promising.

Perivascular epithelioid cell tumor of the cecum： a case report and review of literatures

Perivascular epithelioid cell tumors （PEComas） are a group of rare mesenchymal neoplasms which composed of histologically and immunohistochemically distinctive perivascular epithelioid cells （PECs）. In recent years, PEComas have been manily reported in liver, kidney, lung, uterus and adnexa,1 but rare in small or large intestine.2-6 Here, we describe a case of PEComa restricted in the cecal mucosa, which displayed histological characteristics of epithelioid clear cells.