Erdheim-Chester Disease in a Patient after Double Lung Transplantation for Pulmonary Langerhans Cell Histiocytosis.

Both, Langerhans cell histiocytosis (LCH) and Erdheim-Chester Disease (ECD) belong to the heterogeneous group of histiocytoses. Their association is exceptional and thought to be linked to the BRAF mutation. Both diseases express with different radiographic and histopathologic phenotypes. Radiological features of pulmonary LCH include cystic and fibrotic changes sparing the costophrenic angles. On histology, positive staining with CD1a and Langerin is characteristic. Lung transplantation is the only therapeutical option in end-stage LCH. Radiologic manifestations of ECD include sclerotic bone lesions, retroperitoneal fibrosis, and cardiovascular involvement with infiltration of tissues by foamy histiocytes negative for CD1a. With an end-stage pulmonary LCH, a 38 years old man received a double lung transplantation (DLuTX). The explanted lungs revealed on histology clusters of Langerhans cells histiocytes positive for CD1a. Nine years after DLuTX and continuous immunosuppression, a PET-CT presented sclerotic changes in the scapula and 3rd thoracic vertebra, soft-tissue infiltration of the right atrium and circumferentially surrounding aorta and right coronary artery ("coated" aspect) and edematous thickening of the renal capsule ("hairy kidney"). The imaging findings were thus compatible with ECD. Bone biopsy showed fibrosis of the bone marrow. Biopsy of the retroperitoneum revealed fibrosis, cells inconsistent with Langerhans cells, immune-histochemically lacking CD1a expression. The mediastinal changes slowly progressed over years, requiring biopsy, which also yielded fibrotic tissue. Additionally, the patient developed a massive jaundice and anorexia. The abdominal CT showed intra- and extrahepatic cholangiectasis with circumferential soft tissue sheathing of the common bile duct (CBD). An ERCP with biopsy of the CBD revealed cells positive for langerin and CD1a. Further cranial CT showed symmetric sclerotic bone lesions. Patient died 12 years after DLuTx due to cardiovascular complications. He had never developed any dysfunction of his lung allografts. Distinctive histopathologic results of various tissues at different time points and the extensive radiologic features in the same patient indicate the concomitant occurrence of two distinct histiocytoses, LCH and ECD after DLuTX. [ABSTRACT FROM AUTHOR]