Plasma cell tumors of the skull base are rare in neurosurgical practice. True 
solitary osseous plasmacytoma of the skull base without development of multiple 
myeloma is extremely rare. We report a case of typical Gradenigo's syndrome, 
including left abducens nerve palsy, left facial pain and paresthesia in V1 and 
V2 distribution of trigeminal nerve caused by solitary osseous plasmacytoma of 
the left petrous apex. The patient was a 46-year-old man who presented with 
diplopia for two days. Magnetic resonance imaging (MRI) of the brain showed a 
hyperintense mass on T1-weighted images and slightly hypointense mass on 
T2-weighted images in the left petrous apex and left parasellar area. Through a 
left subtemporal middle fossa approach, subtotal resection of the lesion was 
performed. Histopathological examination of the lesion revealed plasmacytoma. 
The patient received 54 Gy radiation for the local tumor. Four months after 
radiation, the abducens palsy improved. Four years after treatment, the patient 
remained well with no symptoms or signs of local recurrence or progression to 
multiple myeloma.