Prognosis and expression of lambda light chains in solitary extramedullary plasmacytoma of the head and neck: two case reports and a literature review.

Two cases of extramedullary plasmacytoma (EMP) of the head and neck, an uncommon plasma cell neoplasm, were studied. Both patients had good outcomes and have been followed for 17 and 12 years without recurrence or systemic disease. In these two cases, the tumours measured were 4 cm and 0.3 cm, and both cases were positive for lambda light chain restriction on immunohistochemistry. Prognostic factors were considered, based on a review of EMP of the head and neck, including published reports and the authors' clinical experience. Of all plasma cell tumours, EMP has the best prognosis, especially when located in the head and neck region. Variation in the biological behaviour of EMP and the limited number of documented cases make it difficult to determine prognostic factors. Some series have found that age, tumour size, site of origin (extramedullary versus bone), grade, M-protein, light chains and radiotherapy dose all influence the outcome in EMP patients.