Exclusive Pulmonary Involvement in Erdheim-Chester Disease: A Rare Presentation

Erdheim-Chester disease (ECD) is a rare condition classified as a non-Langerhans cell histiocytosis. We present a case of 40-year-old man with dyspnea and chronic cough. Thoracic CT scan showed bilateral pulmonary consolidations. Histological study of the CT guided biopsy revealed a proliferation of large cells with histiocytic features. On immunohistochemistry, the CD68 marker showed positive staining and confirmed the histiocytic nature of these large cells, which also expressed CD45, CD79, and CD99. In contrast, the staining of the histiocytic cells was negative for CD1a.