Non-Langerhans-Cell Histiocytoses

Non-Langerhans-cell histiocytoses include a myriad of histiocytoses, many of which have primarily cutaneous manifestations. The following have been described in the lung.

Part 1 Erdheim-Chester Disease

Timothy C. Allen

Erdheim-Chester disease is a rare nonfamilial histiocytic disorder of unknown etiology. It primarily affects adults middle-aged and older, and bone pain is the most common presenting symptom. It has characteristic long-bone radiographic findings, namely, sclerotic changes in the diaphyses and metaphyses. Approximately half of cases have involvement of nonosseous tissue, and lung involvement occurs in approximately 20% of cases. Differential diagnosis includes pulmonary Langerhans-cell histiocytosis, Rosai-Dorfman disease, and usual interstitial pneumonia.

Histologic Features

Accumulation of foamy or clear histiocytes with variable amounts of associated fibrosis and a variable lymphoplasmacytic infiltrate.
Histiocytes and associated fibrosis and inflammation lie in a characteristic lymphangitic distribution: subpleural, intralobar septal, and bronchovascular.
Generally immunopositive for CD68 and factor XIIIa and immunonegative for CD1a; S-100 immunostain is variably positive.