Lymphoid interstitial pneumonia after allogeneic bone marrow transplantation. A possible manifestation of chronic graft‐versus‐host disease

Interstitial pneumonia (IP) is a frequent and serious complication of bone marrow transplantation with a median time of onset about 2 months posttransplant. Most cases result either from toxicity of radiation and chemotherapy or from infection with pathogens such as cytomegalovirus. Described are two patients with chronic graft‐versus‐host disease (GVHD) who presented with late‐onset IP 242 and 632 days posttransplant. Histologic examination of lung biopsy specimens disclosed a lymphoid interstitial pneumonia (LIP) in both cases. The major lymphocyte subset found in bronchoalveolar lavages and lung tissue was OKT8(+) and showed a positive dot staining for acid phosphatase. Contrary to peripheral blood mononuclear cells, most OKT8(+) lymphocytes in the lungs were OKT3(‐). Since acute GVHD lesions are mediated mainly by cytotoxic T‐lymphocytes, our data suggest that LIP in marrow‐grafted patients may be a manifestation of chronic GVHD. It should be distinguished from the more common types of IP encountered following bone marrow transplantation.