[Primary pulmonary plasmacytoma. Case report of a rare lung tumor]

A 45-year old man, suffering from dry cough without haemoptysis, was admitted for evaluation of pulmonary changes of uncertain aetiology. A chest radiograph and computed tomography (CT) had shown a large space-occupying lesion in the left hilus. His general condition was poor and he had resting dyspnoea and stridor. On auscultation of the lung there were decreased breath sounds and dry rales over the left and vesicular breathing over the right lung.

CT revealed a 7.0 x 6.0 cm space-occupying lesion in the left hilus and ipsilaterally a tumour in the dorsolateral lower lobe surrounding the left lower lobe bronchus. Initial bronchoscopy showed this bronchus to be involved in the tumour process. Biopsy demonstrated monomorphic proliferating plasma cells which on immunochemical testing showed selective staining to lambda-light chains and immunoglobulin G. The first serum electrophoresis was unremarkable, but a later repeat discovered a small amount of paraprotein for IgG-lambda type. Bence-Jones protein was demonstrated in the urine. On the basis of these findings an extramedullary plasmacytoma of the lung (PPP) was diagnosed.

At first the patient was given i.v. chemotherapy, and to prevent a threatening bronchial occlusion oral dexamethasone was given. Pericardial effusion and recurrent retention pneumonia developed. 6 month after onset of symptoms radiotherapy was begun and the tumour became markedly smaller.

PPP should be included in the differential diagnosis of pulmonary space-occupying lesions even when initial serum protein electrophoresis is negative for monoclonal paraproteinaemia. Pericardial effusion may be caused by pulmonary involvement of the plasma cell tumours.