Malignant melanoma arising from the sphenoidal sinus--case report.

Malignant melanomas arising from the sella turcica or sphenoidal sinus with bilateral invasion of the base of the skull or cavernous sinus are extremely rare. Whether the sella turcica or sphenoidal sinus is the site of origin is difficult to determine based on neuroradiological findings. An 83-year-old Japanese female presented with headache as the initial symptom. She suffered rapid progression of bilateral obstruction of the nasal cavity, left nasal bleeding, and bilateral visual field defects. The preoperative diagnosis was pituitary adenoma, metastatic tumor, or malignant paranasal tumor. Biopsy was performed. The histological diagnosis was malignant melanoma. Postoperatively, the tumor progressed rapidly. She suffered several cranial nerve pareses and hypopituitarism. She died within 6 months. Tumors arising from the sphenoidal sinus cause obstruction of the nasal cavity or nasal bleeding first, and then cause cranial nerve pareses by invasion of the cavernous sinus. This sequence of clinical manifestations can be attributed to the anatomical relationships between the sphenoidal sinus, nasal cavity, and cavernous sinus. Differential diagnosis of the origin in the sella turcica or sphenoidal sinus appears to be relatively easy based on further observation of the clinical course and symptoms.