An Unusual Case of a Malignant Lip Perivascular Epithelioid Cell Tumour ( <scp>PEComa</scp> )

ABSTRACT Introduction We report a case of a malignant perivascular epithelioid cell tumour (PEComa) appearing as a swelling on the lower lip. PEComas are mesenchymal neoplasms that contain the distinctive perivascular epithelioid cell. They range from malignant to benign. PEComas occur around blood vessels, infiltrating the smooth muscle of small to medium‐sized vessels. Aim We believe this is a unique case report, the first malignant PEComa case of the lip reported in the literature so far. We hope this case report educates our colleagues on PEComas and how the heterogeneity of initial biopsy samples can prove diagnosis difficult during the initial incisional biopsy stage. Methods This case details a 39‐year‐old female patient who was referred to the oral surgery department by her GP (General Practitioner) for a new‐onset swelling of the lower left lip. The swelling was symptomatic with pain and numbness. The initial incisional biopsy of the lesion proved insufficient for diagnosis due to the heterogeneity and uncertain histology of the sample; it only pointed to a fibrohistiocytic tumour, which was difficult to classify. Only after wide local excision of the lesion was a diagnosis of malignant PEComa established. Conclusion The case highlights how histological analysis of incisional biopsies of PEComas makes initial diagnosis difficult. This case further explores and compares several PEComa cases that present intraorally in the literature, both benign and malignant. It examines treatment modalities of PEComas with surgical treatment, remaining the recommended treatment for PEComas. Currently, there is no consistent evidence that can support adjuvant approaches such as chemotherapy or radiotherapy. Malignant PEComa can be aggressive; local and distant metastasis is possible; therefore, a close clinical follow‐up was arranged in our case.