Malignant peripheral nerve sheath tumor with rhabdomyoblastic differentiation and glandular component

An exceptional case of malignant peripheral nerve sheath tumor with striate d muscle differentiation and glandular component is reported, in a 52-year old man. This tumor measured 8 cm in diameter, and was localized in the che st wall, infiltrating the skeletal muscle. The mesenchymal portion of the t umor was composed mostly of spindle cells arranged in interlacing fascicles . Between these fascicles, there were large cells with abundant eosinophili c cytoplasm and clear elongated nucleus. Immunohistochemical study demonstr ated cytokeratin, EMA and CEA expression in the glandular component and S10 0 protein expression in the major portion of the mesenchymal component. The large cells identified as rhabdomyoblasts, expressed desmin, myoglobin, al pha-SR actin and alpha-SM actin. The tumor recurred 5 years after its resec tion. Histological and immunohistochemical features were identical. We thin k that positivity of neoplastic striated muscle cells with alpha-SM actin r eflects an early differentiation phase of these cells.