[Bone marrow granulomas]

To evaluate bone marrow granulomatous lesions in order to establish their etiology.

2,250 bone marrow biopsies were studied during the period of March 1983-March 1991. Granulomas and/or granulomatous lesions were found in 24 of them (1.06%). A correlation between histological characteristics, special stains: PAS, Ziehl Neelsen and Grocott and cultures were done. Immunohistochemistry was done to evaluate B or T cell-lineage in 4 patients.

The 24 patients were biopsied because of the clinical diagnosis of haematological and non-haematological neoplasias, infections, AIDS, sarcoidosis and fever of unknown origin. Bone marrow cellularity ranged from 20% to 75% (M: 49.8%). Myeloid cells were increased in 54% of the cases. The number of granulomas ranged from 1 to 19 (M: 3.9). The epithelioid cells were the predominant component in 66% of the cases. Of the 7 patients with non-Hodgkin's lymphoma, 4 had lymphomatous involvement with granulomatous pattern. These cases showed predominance of lymphoid cells and vessels in addition to epithelioid cells.

We consider that in order to establish a relationship between infection and granuloma, the identification of a microorganism through a culture is a more reliable test. We couldn't find any morphological characteristic which allowed an etiologic diagnosis of bone marrow granulomas. In case of lesions with a great lymphocytic and vascular proliferation plus the presence of epithelioid cells and fibrosis, NHL with bone marrow involvement with a granulomatous pattern should be strongly considered.