RESUMO

Extramedullary plasmacytoma represents less than 5% of plasma cell malignancies, 85% corresponding to head and neck masses. Symptoms are related to compressive effects according to location, aesthetics issues and can be misleading associated with soft tissue disorders. In this case report, we discuss a 70-year-old woman who presented with a 3-month history of a growing painless forehead lump and confusion, for which she had an emergent simple head computed tomography scan. The images revealed a well-defined mass eroding the frontal bone with multiple lytic lesions that were also found along with long bones radiography. The mass biopsy showed a monomorphic plasmatic cell infiltrate, bone marrow studies confirmed the diagnosis of a light chain secreting multiple myeloma. Extramedullary plasmacytoma is a very unusual first presentation form of multiple myeloma and represents a clinical and radiological challenge. A systematic approach of lytic bone lesions along with the differential diagnosis of head masses are skills the clinician should develop to promptly recognize this condition considering further complications of delayed treatment. In this case, the histopathological confirmation allowed the patient to avoid neurosurgery and the early start of systemic chemotherapeutic treatment.