[Cardiac glomus tumor: An unusual localization of pericytic (perivascular) tumor]

Glomus tumor are rare mesenchymal neoplasm, belonging to the pericytic (perivascular) tumor family, witch recent molecular characterization has allowed highlight recurrent molecular abnormalities. In fact, glomus tumor involves frequent MIR143-NOTCH gene fusion whereas others pericytic tumor (myopericytoma and myofibroma) involve mutations of PDGFRB gene. Glomus tumor are usually developed in superficial localization. However visceral locations have been described. Cardiac location is exceptional with only one case reported in literature. Here, we report the case of cardiac glomus tumor (glomangiomyoma) developed in the left ventricle in a 34 year-old patient, diagnosed after chest pain. The length of tumor was 4cm in greatest dimension. Histologically, the tumor concerned both round glomus cells and smooth muscle cells with prominent branching thin-walled vessels. By immunohistochemistry, these two contingents exhibited diffuse expression of smooth muscle actin and heterogeneous expression of H-caldesmone whereas cytokeratins, melanocytic markers and chomogranine were negative. Next Generation molecular analysis using RNA sequencing highlighted the characteristic MIR143-NOTCH gene fusion witch supports the diagnosis of glomus tumor. In this observation, we recall histological and immunohistochemistry features of glomus tumor and we make a synthesis concerning the molecular data recently described in sporadic glomus tumor.