Introduction: Perivascular epithelioid cell tumour (PEComa) is a rare family of mesenchymal tumours composed of epithelioid cells. Due to its very rare occurrence, little information is available on the imaging characteristics of this type of lesion. Case Report: A 16-year-old patient was admitted for diagnosis of an incidentally found lesion of unclear origin on MRI of the lumbar spine. Targeted MRI revealed a pathological solid-cystic mass within the pelis, in the left rectovesical pouch, infiltrating the bladder wall. A biopsy of the tumour was performed. On histopathological examination, a PEComa tumour was diagnosed. Control examinations were performed. The tumour was treated with embolization, surgical resection and Sirolimus therapy. Conclusions: The tumour showed the characteristic features of PEC-oma on imaging studies reported in the literature. Radiological diagnosis is not fully specific, therefore histopathological examination is necessary for a definitive diagnosis.