Divergent differentiation in medulloblastoma; a potential diagnostic trap

Abstract

Background Medulloblastoma is the most common malignant tumour of the childhood, and usually arises from the cerebellar vermis. Several histological variants of medulloblastoma have been described. Myogenic and melanotic differentiated medulloblastoma are rarely seen. Cases series We describe four cases of medulloblastoma, two with myogenic differentiation and two with melanotic differentiation, reported at LabPlus, Auckland City Hospital, between 2005 and 2013. The four cases were for children aged 2-11 years old. Discussion Medulloblastoma with myogenic differentiation (medullomyoblastoma) is a rare tumour of the CNS; its first published description was in 1933. Microscopically, it is characterised by a mixture of neuroectodermal and rhabdomyoblastic cells. The current treatment is similar to the treatment strategy for patients with medulloblastoma. Medulloblastoma with melanotic differentiation (melanotic medulloblastoma) is another rare variant of medulloblastoma, first described in 1962. Microscopically it is characterised by classic medulloblastoma cells in addition to melanin containing cells which are often arranged in small clusters or tubules. The few reported cases indicate that this variant may imply greater resistance to therapy and a worse prognosis. Medulloblastoma is the most common malignant tumour of the childhood, and usually arises from the cerebellar vermis. Several histological variants of medulloblastoma have been described. Myogenic and melanotic differentiated medulloblastoma are rarely seen. We describe four cases of medulloblastoma, two with myogenic differentiation and two with melanotic differentiation, reported at LabPlus, Auckland City Hospital, between 2005 and 2013. The four cases were for children aged 2-11 years old. Medulloblastoma with myogenic differentiation (medullomyoblastoma) is a rare tumour of the CNS; its first published description was in 1933. Microscopically, it is characterised by a mixture of neuroectodermal and rhabdomyoblastic cells. The current treatment is similar to the treatment strategy for patients with medulloblastoma. Medulloblastoma with melanotic differentiation (melanotic medulloblastoma) is another rare variant of medulloblastoma, first described in 1962. Microscopically it is characterised by classic medulloblastoma cells in addition to melanin containing cells which are often arranged in small clusters or tubules. The few reported cases indicate that this variant may imply greater resistance to therapy and a worse prognosis.