Solitary intracranial plasmacytoma

Solitary intracranial plasmacytomas (SIPs) are rare tumours that may be mistaken radiologically for meningiomas. According to the literature, the predominant feature on polytomography and computed tomography (CT) is a bone-eroding, contrast-enhancing soft tissue mass, part of which might have extended extracranially before initial presentation. The lesions can be solitary and are therefore amenable to surgical excision. Although no recurrence is seen for up to 10 years after treatment, some authors believe progression to multiple myeloma is inevitable. Lesions that are extramedullary in origin are thought to have the best prognosis. We describe three cases treated surgically at Westmead Hospital in the past 6 years. All had CT features similar to those reported previously. On magnetic resonance imaging, which in this condition has not been fully documented, the lesions were slightly hyperintense with the brain on T1-weighted sequences, and were inhomogeneous and hyperintense with T2-weighted images. The two patients who received intravenous contrast showed dense and uniform enhancement. Occasional intralesional signal voids suggested increased vascularity, which was confirmed surgically. The presence of intracellular immunoglobulins may account for the hyperintensity on T2 sequence. Although no specific imaging features were identified to distinguish meningiomas from SIP, the latter should be included in the differential diagnosis of solitary bone eroding intracranial tumours.