PONTINE NEUROCYTOMA

A case of neurocytoma arising in the rostral pontine region of an 18 y ear old man is reported. The patient developed a right trochlear nerve palsy and was shown to have a well circumscribed, contrast enhancing mass on magnetic resonance imaging. The tumour was characterised histo logically by a uniform population of medium sized round nuclei and sli ghtly eosinophilic cytoplasm or occasional perinuclear halos, with del icate branching capillaries, patches of fibrillary matrix, and occasio nal perivascular pseudorosettes. Immunohistochemical studies demonstra ted strong reactivity for synaptophysin in the fibrillary processes an d cytoplasm of tumour cells. The present tumour is an exceptional case of neurocytoma arising in the pens.