[Solitary intrasellar plasmocytoma revealed by a diplopia: a case report]

Plasmocytomas rarely invade the skull base. It can be solitary or multiple. The clinical presentation mainly consists in a progressive neuropathy involving many cranial nerves, or may simply present as an optochiasmatic syndrome.

The authors report a case of a female patient aged 68 years presenting with an optochiasmatic syndrome with an anosmia and paralysis of the right sixth (VI) cranial nerve progressing over two years prior to her hospitalisation. Cerebral MRI showed a voluminous intrasellar lesion, isointense on T1 and hyperintense on T2, enhancing intensely after gadolinium injection with evidence of invasion of the sphenoid and cavernous sinuses. The endocrinologic assay was normal. A sphenoidal biopsy by the rhinoseptal route permitted the diagnosis of a plasmocytoma. A complete radiologic and laboratory assessment of the patient was accomplished, the patient benefited from local radiotherapy.

Plasmocytomas are malignant tumors that are essentially osseous. The cervicocephalic region is rarely afflicted (1%). Extension to the cranial base seldom occurs. Less than 30 cases have been described in the literature simulating the other numerous neoplastic intrasellar lesions.

Plasmocytomas of the cranial base revealing a myeloma represent a very rare entity. Nevertheless, whether solitary or multiple, a plasmocytoma must be considered amongst the differential diagnoses in the face of any invasive lesion of the sphenoid sinus.