Primary Ovarian Perivascular Epithelioid Cell Tumor Diagnosed During Pregnancy: A Case Report and Review of the Literature

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms with dual melanocytic and smooth muscle differentiation. Ovarian PEComas are extremely rare, and to our knowledge, this is the first reported case diagnosed during pregnancy. A 31-year-old pregnant woman underwent resection of a left adnexal mass at an external facility. Histopathology assessed at the pathology department of Shaukat Khanum Memorial Cancer Hospital & Research Centre (SKMCH&RC) revealed a PEComa. Follow-up imaging at our center showed a residual complex solid-cystic mass in the left adnexa. Multidisciplinary discussion led to fertility-sparing surgical staging, including left salpingo-oophorectomy, pelvic wall mass excision, and infracolic omentectomy. Histopathology confirmed primary ovarian PEComa with metastatic deposits in the pelvic sidewall and omentum. Targeted therapy was deferred until after delivery. Microscopically, the tumor displayed epithelioid and spindle cells with perivascular arrangement and eosinophilic cytoplasm. Immunohistochemistry was positive for human melanoma black-45 (HMB-45) and smooth muscle actin. Features of malignancy included necrosis, mitotic activity of more than two per 50 high-power field (HPF), and vascular invasion. A review of 12 published cases of ovarian PEComa revealed variable morphology and outcomes. Malignant potential is best predicted by tumor size, mitotic index, necrosis, and nuclear atypia. While surgery remains the primary treatment, the role of adjuvant therapy is evolving. This case highlights the diagnostic challenge of ovarian PEComa during pregnancy and emphasizes the importance of histologic classification and multidisciplinary management in guiding treatment decisions.