Amylose localisée à chaîne légère kappa se présentant sous forme d’une masse médiastinale

[A rare cause of pulmonary arterial hypertension: Thoracic amyloidosis]

Isolated thoracic involvement in amyloidosis is a rare and serious condition. Its association with pulmonary arterial hypertension (PAH) usually weakens the prognosis. We report the case of a 40-year-old man with a smoking history, hospitalized for chest pain, abdominal pain and acute respiratory distress. The cardiac ultrasound revealed a circumferential pericardial effusion as well as a pulmonary artery systolic pressure (PAPS) at 80mmHg. Chest imaging (computed tomography scan and magnetic resonance imaging) showed a tissue process developed in the pericardial sheath (60×45mm) sheathing the ascending aorta and infiltrating the trunk of the pulmonary artery and its right branch. Anatomopathological and immunohistochemical study of the process revealed AL amyloidosis. Note that the patient had no signs of extrathoracic amyloidosis. Blood and urine electrophoresis and immunoelectrophoresis as well as bone marrow mylogram and biopsy were normal. The patient was put on oral anticoagulant as he presented with PAH. A therapeutic protocol with thalidomide and dexamethasone has been initiated. The course of the disease was marked by total regression of the clinical signs, a marked decrease in the amyloid process on imaging and a normalization of the PAPS; our follow-up being three years.