[Differentiation of granulomatous lesions in the bone marrow]

Granulomas are an infrequent finding in bone marrow biopsies and may be associated with a broad spectrum of infectious and non-infectious disorders. In this context sarcoidosis generally reveals the highest incidence of such bone marrow lesions. Other granulomas may be encountered in drug-induced secondary changes (toxic myelopathy) and in particular also in HIV myelopathy. In these cases the granulomas are small, ill-defined and difficult to recognize. Special staining methods are required to detect microorganisms. Fibrin ring granulomas (doughnut granulomas) are typical for Q-fever, but may also be seen in reactive conditions, after drug therapy and in the course of other infectious disorders, such as Lyme disease. Therefore a broad serological testing should be performed. In conclusion, in most cases the morphological findings in the bone marrow are not specific so that a synoptical approach regarding histological, clinical and serological data is warranted to reach the correct diagnosis.