Transthyretin amyloidosis with pulmonary involvement in a patient with monoclonal gammapathy

Pulmonary involvement in the course of systemic senile amyloidosis caused by non-mutated transthyretin is rarely described. We report on concomitant monoclonal gammapathy of undermined significance (MGUS) and amyloidosis with non-mutated transthyretin with diffuse lesions in lung parenchyma. A female patient, 67 years old, was admitted with dyspnoea, malaise, weight loss, and disseminated radiological lesions in the lungs. On lung HRCT, signs of pulmonary hypertension, alveolar and interstitial involvement, with thickening of septal lines were found. Echocardiography revealed severe pulmonary hypertension, and electromyography revealed sensoromotoric polyneuropathy with axon and myelin damage. Pathological assessment of lung specimens revealed nodular deposits of amyloid in the bronchial walls and lung parenchyma Congo red staining was positive. Specimens of colon mucosa confirmed amyloidosis. Stainings for AA, AL and beta2-microglobulin were negative but were positive for transthyretin. Bone marrow trepanobiopsy indicated monoclonal gammapathy of MGUS type; Congo red staining was positive. Transthyretin amyloidosis with vascular involvement, particularly of arteriovenous anastomoses, including pulmonary vessels and an insignificant amount of AL protein (perhaps secondary imbibition with AL protein from serum) was diagnosed in amyloid deposits. No mutations of the transthyretin gene (exon 1,2,3,4) were found. The patient was treated with methylprednisolone, melphalan and then with cyclophosphamide. Radiological examinations performed 1 and 2 month/s after initiation of therapy showed progression of pulmonary lesions. The patient died one month later; an autopsy was not performed.