Endometrial polyp-like perivascular epithelioid cell neoplasm associated with TFE3 translocation: report of one case

This article reports the pathologic features and malignant biological behavior of a perivascular epithelioid cell neoplasm (PEComa) with the clinical manifestation being endometrial polyps. The case was cured with curettage in a local hospital one year ago. The postoperative diagnosis was "endometrial polyps". This time, due to "irregular bleeding", we carried out another curettage in our hospital. After the operation, 3 pieces of polyps were inspected with diameters of 0.3 cm, 0.5 cm and 0.6 cm, respectively. The tumor consisted of epithelioid cells with alveolar and nesting pattern and showed a diffuse strong expression of HMB45, Melan-A and TFE3. The patient then underwent a hysterectomy and the "polyps" were sent for pathological examination. The result showed that tumor cells infiltrated the deep muscle layer, close to the outer membrane, suggesting a malignant biologic behavior. TFE3-related PEComa is different from general PEComa. This neoplasm and Melanotic Xp11 renal carcinoma have similar clinicopathologic features, histology, immunity and molecular phenotypes, belonging to the same type of tumor. It has been suggested in the literature naming this neoplasm as 'Xp11 neoplasm with melanocytic differentiation' or 'melanotic Xp11 neoplasm'. Our case has expanded our understanding of PEComa characteristics and increased data for TFE3 translocation-related PEComa, reminding us to avoid misdiagnosis when PEComa manifests as small polyps.