Cytodiagnosis of multiple myeloma presenting as orbital involvement: a case report

Plasma cell neoplasms represent autonomous proliferations of plasma cells and can manifest as diffuse myeloma with systemic involvement (plasma cell myeloma or multiple myeloma), monoclonal gammopathy of undetermined significance (MGUS), or as variants of plasma cell myeloma such as indolent myeloma, smoldering myeloma, osteosclerotic myeloma, plasma cell leukaemia and non-secretory myeloma. Localized neoplastic proliferation of plasma cells presents as solitary plasmacytoma of bone or extramedullary plasmacytoma. Involvement of orbit can occur as a solitary plasmacytoma, or as part of systemic involvement in multiple myeloma, the clinical outcome being significantly worse in the latter setting. Orbital involvement in multiple myeloma is very rare with less than 50 cases reported in the literature. Early cytological diagnosis of such lesions is vital for timely institution of appropriate therapy. As far as we are aware only six previous cases of cytological diagnosis of multiple myeloma involving the orbit are on record.

A 37 year old male presented with low grade fever showing evening rise, headache, diplopia and swelling in the right periorbital and temporal region. Imaging studies revealed destructive lesion of sphenoid, frontal bone and zygomatic arch with soft tissue component extending to infratemporal fossa and orbit. A fine needle aspirate from the temporal region swelling showed features of a plasmacytoma, and subsequent workup confirmed the presence of systemic disease. A final diagnosis of multiple myeloma with orbital involvement at presentation was made.

Present case describes the extremely rare presentation of multiple myeloma with orbital involvement and highlights the utility of cytology in such lesions. Fine needle aspiration diagnosis of plasmacytoma at extramedullary sites offers an opportunity for non-invasive verification of systemic involvement, and thus plays a major role in early diagnosis and management of these patients.