Congenital Myoepithelial Carcinoma of Soft Tissue Associated With Cystic Myoepithelioma

Myoepithelial neoplasms of soft tissue represent a heterogeneous group of lesions, encompassing both benign entities as myoepithelioma (ME) and highly aggressive tumors as myoepithelial carcinoma (MEC). We describe a case of pediatric soft tissue MEC with peculiar features that may lead to misdiagnosis: congenital onset and presence of a benign component with predominant cystic structure. Few cases of congenital MEC have been reported, but the coexistence of MEC with ME is even more rare, accounting for less than 1% of myoepithelial tumors. Moreover, an extensive cystic appearance had never been described in either ME or MEC of soft tissue. Despite several predictors of poor prognosis, the patient has been showing a favorable clinical course since the administration of ICpE (ifosfamide, cisplatin, and etoposide) chemotherapy. This report provides valuable information in the differential diagnosis of cystic congenital tumors and supports a possible efficacy of adjuvant combined treatment for patients with localized disease after surgery.