Metastatic Malignant Perivascular Epithelioid Cell Tumor (PEComa) in Parotid Gland Diagnosed by Fine Needle Aspiration Biopsy- a Case Report and Literature Review

Abstract

Perivascular Epithelioid Cell Tumors (PEComas) are exceedingly rare mesenchymal tumors in salivary glands; no case of metastatic malignant PEComas in salivary gland was described. Here we reported a case of a 74-year old female with a history of malignant PEComa of retro peritoneum, who underwent surgical resection 11 years ago. She had metastatic PEComas in her liver and right upper extremity 7 months prior to the current presentation, with a 0.6 cm soft mobile palpable nodule in the right parotid region without tenderness. Fine needle aspiration biopsy showed spindle-shaped cells with indistinct cell border, wispy acidophilic cytoplasm, and oval to cigar-shaped hyper chromatic nuclei with evenly distributed fine chromatin. No epithelioid form was identified. Immunohistochemistry study showed the neoplastic cells were positive for smooth muscle actin, h-caldesmon and negative for cytokeratin, S-100 and HMB-45. Diagnosis of metastatic malignant Perivascular epithelioid cell tumor was made and the patient was continued with chemotherapy. This case is the first report of metastatic malignant PEComa in parotid gland. The patient’s known history of malignant Perivascular epithelioid cell tumor is important when cytopathologists make the differential diagnosis for the mesenchymal neoplasm of salivary gland. Perivascular Epithelioid Cell Tumor (PEComa) is a family of mesenchymal neoplasms [1-2]. The most common PEComas include renal Angiomyolipoma (AML), pulmonary Lymphangioleiomyomatosis (LAM) and Clear Cell Sugar Tumor (CCST) of the lung. It is exceedingly rare in salivary glands, to our knowledge, only 3 cases of primary angiomyolipoma of parotid gland were reported [3]. No case of metastatic malignant PEComas in salivary gland was described. We report a case of metastatic malignant PEComa in parotid gland diagnosed by fine needle aspiration biopsy. The literatures on this rare mesenchymal neoplasm are reviewed.