Multiple myeloma in remission complicated by bone marrow granulomas

Granulomas are encountered in 1-2% of biopsies performed in various hematological and non-hematological diseases. Almost 50% of bone marrow granulomas are associated with infections and 25% with hematologic disorders, especially lymphoma and multiple myeloma. Toxoplasmosis is reported to induce granulomas in bone marrow inmunosuppressed patients. On the other side, long-term unexplained remissions after conventional treatment in multiple myeloma were mentioned in up to 10% of cases.

A 56-years-old female patient was diagnosed with IgG(kappa) multiple myeloma in 1992. After 5 years, being still in complete remission, frequent bone marrow epithelioid non-caseating granulomas were noticed in biopsy, without clinical symptomatology or modifications of routine paraclinical examinations. The history revealed no treatments with antiarrhythmic, antihypertensive, anticonvulsivants or nonsteroid antiinflammatory drugs. The serologic tests for other infections or systemic diseases known to induce granulomas were negative, except those for toxoplasma gondii IgG. The treatment with azithromycine and pyrimethamine induced the disappearance of granulomas, simultaneously with an important decrease of anti-toxoplasma IgG antibodies titer.

The bone marrow granulomas provide a valuable histologic clue to opportunistic infections and the bone marrow biopsy is useful for their diagnosis. In the specific case of toxoplasmosis, a recently proposed treatment with azithromycin induced the resolution of the granulomas. Due to the usual lack of specificity of the most bone marrow granulomas, a broad and long-term clinical, histopatological and serological follow-up to establish the etiology should be performed.