title: Paraganglioma of the orbit - an exercise in diagnosis. A case report.
abstract: A case is described of a child presenting with an extremely large orbital tumour, which had an alveolar pattern on histological examination. The differential diagnosis, which included alveolar rhabdomyosarcoma, alveolar soft-part sarcoma and non-chromaffin paraganglioma, could only be made on electron microscopic examination. Exact diagnosis was important because of prognostic and therapeutic implications. The presence of neurosecretory granules in tumour cells was demonstrated on electron microscopy, confirming the diagnosis on non-chromaffin paraganglioma, a benign tumour which is extremely rare in this site.
mesh_terms: D002648:Child; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D009918:Orbital Neoplasms / Q000175:diagnosis* / Q000473:pathology; D010236:Paraganglioma, Extra-Adrenal / Q000175:diagnosis* / Q000473:pathology / Q000648:ultrastructure; D012208:Rhabdomyosarcoma / Q000175:diagnosis; D012509:Sarcoma / Q000175:diagnosis