A very rare case of uterine PEComa HMB45 negative: primitive or relapse?

Perivascular epithelioid cell tumors (PEComas) represent a rare group of tumours with uncertain malignancy potential exhibiting an immunophenotype characterized by actin and Human Melanoma Black 45 (HMB45) immunoreactivity. Our case concerns about a rare malignant uterine perivascular epithelioid cell tumour diagnosed in a patient underwent to subtotal hysterectomy with unclear diagnosis, 12 years before. Histological diagnosis after colposcopic exam with biopsy revealed a perivascular epithelioid cell tumor, with immunohistochemical profle negative for HMB45. Negativity for HMB45, already described in literature, could be due to important cellular modifcations of tumoral tissue. In our case, tumour was unresectable, progression of disease occurred during medical treatment and the patient died after 6 months. Lack of information about frst surgery doesn't allow to surely categorized the tumor as primitive or relapse. Further studies are necessary to understand some immunohistochemical anomaly like negativity for HMB45.