Sellar region extramedullary plasmacytoma – A rare skull base tumour

Abstract

Plasma cell neoplasms can present either as multiple myeloma, or in <10% of cases, as solitary plasmacytoma. Extramedullary plasmacytoma, a subtype of solitary plasmacytoma, only accounts for <5% of all plasma cell neoplasms, and <1% of all head and neck tumours. Extramedullary plasmacytoma usually arises from aerodigestive tract, and infrequently, from skull base and calvarium. Sellar region extramedullary plasmacytoma is a relatively rare tumour in the sellar region. Sellar region extramedullary plasmacytoma is usually asymptomatic until the lesion is large enough to impinge on surrounding structures, most commonly the cranial nerves. Radiological findings for extramedullary plasmacytoma are rather non-specific, but MR pituitary provides essential information with regards to its origin and its content, which aid in ruling out other diagnoses. The tumour usually enhanced homogenously post-Gadolinium, without involvement of surrounding bones. Due to the rarity of sellar region extramedullary plasmacytoma, tumour histo-pathological examination is recommended to achieve an accurate tissue diagnosis. Apart from neuroimaging, evaluations for plasma cell neoplasms include total body skeletal survey, serum and urine electrophoresis, routine blood count, serum calcium level and bone marrow biopsy. Principally, the diagnosis of plasmacytoma is confirmed by ruling out the presence of multiple myeloma. As for management of extramedullary plasmacytoma, local irradiation is the treatment of choice. Nonetheless, surgery is required for tissue diagnosis and tumour debulking in patients with neurological deficit due to mass effect.A 48-year-old lady presented with 5 months history of progressive bilateral poor vision and worsening headache. Clinically, she had severe visual acuity and visual field defect, but no other neurological deficit. MR imaging showed a large lobulated sellar mass, homogenously enhanced with extension and invasion to surrounding structures. She had undergone bifrontal craniotomy and tumour debulking. Intraoperatively, the tumour was highly vascularised. Tumour histopathological result was reported as extramedullary plasmacytoma. Serial plasma and urine investigations showed negative results for multiple myeloma. Hence, the final diagnosis of skull base extramedullary plasmacytoma was established. She was then scheduled for adjuvant radiotherapy. Unfortunately, her vision impairment persists. Keywords: Extramedullary plasmacytoma, Skull base tumour, Sellar region tumour, Bifrontal craniotomy, Tumour debulking