Malignant gastrointestinal PEComa misdiagnosed as Solid pseudopapillary neoplasm of ovary: a case report

Background: Perivascular epithelial cell malignant tumor (PEComa) is a mesenchymal tumor with the characteristics of perivascular epithelioid cells in histology and immunophenotype. It mostly occurs in kidney, uterus, liver and so on. Solid pseudopapillary is a tumor that commonly originates in the pancreas. Solid pseudopapillary of ovary is similar to PEComa in histology and is easily misdiagnosed in clinic. This paper reports a case of malignant gastrointestinal PEComa misdiagnosed as solid pseudopapillary neoplasm of ovary. Case summary: A 35-year-old female patient came to our hospital with intermittent right lower abdominal pain for more than 1 month. After the completion of relevant examinations, the possibility of sigmoid colon tumor infiltration in the right adnexa was considered before surgery. On February 12, 2018, the tumor was surgically removed, the pathological examination showed that there was solid pseudopapillary neoplasm of the ovary. The patient received four cycles of chemotherapy with paclitaxel and platinum after surgery. The patient recovered well after operation, and there were no complications. Two years later, a pulmonary nodule was found in the reexamination, and the pulmonary lesions were surgically removed. Immunotherapy (Tislelizumab) and targeted therapy (Apatinib) are then given. After consulting several laboratories and testing institutions, the final diagnosis was (sigmoid colon) Malignant gastrointestinal PEComa involves (right) ovary and (right upper lung) lung metastasis. The patient died a month ago from complications. Discussion: Clinicians must understand PEComa in order to achieve early detection, early diagnosis and early treatment.