Abdominal perivascular epithelioid cell tumor (PEComa) without visible fat: a clinicopathologic and radiological analysis of 16 cases

Case report: Urachal perivascular epithelioid cell tumor

Background

Urachal tumors are rare in clinical practice, among which urachal adenocarcinoma is the most common. In this study, we report a rare case of urachal perivascular epithelioid cell tumor to improve our understanding of the disease.

Case presentation

A 26-year-old male patient was hospitalized for lower abdominal pain. The US showed a hypoechoic mass measuring 26mm × 18mm in the superior aspect of the bladder. MRI showed an irregular mass located anterior to the bladder roof, near the midline. The tumor exhibited hypointense on T1WI and heterogeneous hyperintense on T2WI. Additionally, contrast-enhanced T1-weighted imaging revealed obvious ring enhancement of the tumor. The patient underwent surgical resection of the urachal tumor, with subsequent pathological examination revealing a diagnosis of urachal PEComa. Following surgery, the patient underwent regular follow-up assessments, with no evidence of recurrence or metastasis observed after three and a half years.

Conclusions

Urachal PEComa is a rare mesenchymal tumor that presents challenges in diagnosis through imaging and clinical symptoms. Definitive diagnosis relies on pathological and immunohistochemical analysis. Due to the rarity of urachal PEComa, prognosis assessment necessitates long-term follow-up and evaluation of more cases.

Pancreatic PEComa, a not so uncommon neoplasm? Systematic review and therapeutic update

Pancreatic PEComas are extremely rare neoplasms with malignant potential, which mostly affect middle-aged women and are characterized by presenting melanocytic and myogenic markers in immunohistochemical analysis. There are no symptoms or pathognomonic imaging tests, so the diagnosis is established with the analysis of the surgical specimen or the FNA obtained with preoperative endoscopic ultrasound. The mean treatment consists on radical excision, adapting the intervention to the location of the tumor. To date, 34 cases have been described; however, more than 80% of them have been reported in the last decade, which suggests that it is a more frequent pathology than expected. A new case of pancreatic PEComa is reported and a systematic review of the literature is carried out according to the PRISMA guidelines with the aim of divulge this pathology, deepening its knowledge and updating its management.

Perivascular epithelioid cell tumor (PEComa) of the cystic duct

Perivascular epithelioid cell tumors, also known as PEComas, are rare mesenchymal tumors composed mainly of epithelioid cells found in perivascular tissue. PEComas occur most frequently in the kidney, uterus, the gastrointestinal tract, liver, and retroperitoneum; those originating in the biliary tree are extremely rare. We report a case of benign PEComa of the cystic duct with positive TFE3 staining on immunohistochemistry.A 66-year-old woman was referred for a 20 mm mass adjacent to the common bile duct discovered incidentally on abdominal ultrasound. Laboratory data including tumor markers were unremarkable. The tumor appeared to arise from the cystic duct, showed early enhancement, and compressed the common bile duct on imaging studies. Endoscopic ultrasound-guided fine-needle aspiration revealed round- and spindle-shaped atypical cells with eosinophilic cytoplasm and brown deposits suggestive of melanin granules. Histological examination of the resected specimen revealed a tumor consisting of epithelioid cells forming an alveolar structure, with melanin pigmentation. Immunohistochemistry was positive for HMB-45 and TFE3, consistent with benign pigmented PEComa of the cystic duct. Melanotic, myogenic, and TFE3 staining are helpful when diagnosing PEComas arising in unusual locations.

Large Bowel Ischemia/Infarction: How to Recognize It and Make Differential Diagnosis? A Review

Ischemic colitis represents the most frequent form of intestinal ischemia occurring when there is an acute impairment or chronic reduction in the colonic blood supply, resulting in mucosal ulceration, inflammation, hemorrhage and ischemic necrosis of variable severity. The clinical presentation is variable and nonspecific, so it is often misdiagnosed. The most common etiology is hypoperfusion, almost always associated with generalized atherosclerotic disease. The severity ranges from localized and transient ischemia to transmural necrosis of the bowel wall, becoming a surgical emergency, with significant associated morbidity and mortality. The diagnosis is based on clinical, laboratory suspicion and radiological, endoscopic and histopathological findings. Among the radiological tests, enhanced-CT is the diagnostic investigation of choice. It allows us to make the diagnosis in an appropriate clinical setting, and to define the entity of the ischemia. MR may be adopted in the follow-up in patients with iodine allergy or renal dysfunctions, or younger patients who should avoid radiological exposure. In the majority of cases, supportive therapy is the only required treatment. In this article we review the pathophysiology and the imaging findings of ischemic colitis.