Unusual case of intraosseous primary intracranial malignant melanoma.

Primary intracranial malignant melanoma (PIMM) represents 0.07% of central nervous system tumours; clinical behaviour and prognosis are not well documented. Preoperative diagnosis of PIMM is complex and it could be easily misdiagnosed, especially with malignant meningioma. We are reporting a case of a man with a history of rapidly arising motor slowing associated with urinary incontinence, presenting with mild convergent strabismus caused by paralysis in abduction in the right eye. A brain CT showed a lesion compatible with malignant spheno-orbital meningioma, and the patient underwent gross total resection. Intraoperatively, the blackish lesion infiltrated and eroded the bone; it was placed externally on the dura mater with a mild reaction and without attachment. Histological examination confirmed PIMM. Intraosseous localisation of PIMM has been observed in the basic bone structure of the oral cavity. We report the first intraosseous spheno-orbital PIMM case and present an embryological theory about how this unusual tumour can develop. [ABSTRACT FROM AUTHOR]