Large cell medulloblastoma with myogenic and melanotic differentiation: a case report with molecular analysis.

We present a case of large cell medulloblastoma with myogenic and melanotic differentiation arising in the cerebellar vermis of a 2-year-old boy and following an aggressive clinical course. Histologic and immunohistochemical features of this tumor include primitive neuronal, rhabdomyoblastic, and pigmented epithelial elements, along with large cell features. Immunohistochemical and molecular data (c-myc gene amplification and the presence of isochromosome 17q) support the contention that this histologically diverse tumor represents a pattern of medulloblastoma with striated muscle and pigmented epithelial differentiation, rather than a teratoma or a cerebellar variant of melanotic neuroectodermal tumor of infancy ('progonoma').