Non-caseating granulomata associated with hypocellular myelodysplastic syndrome

Non-caseating granuloma (NCG) remains a histopathological hallmark for sarc oidosis. Although the exact mechanism for NCG formation is unknown, the pat hogenesis may involve a disordered antigen presentation in the monocyte/mac rophage system, functional abnormalities in activated T-lymphocytes and unc ontrolled cytokine production. Similar immunological dysfunction has been d escribed in myelodysplastic syndrome (MDS). However, the association of NCG and MDS is rarely documented. We report a case of hypocellular MDS associa ted with generalized NCG. Despite treatment for both sarcoidosis and tuberc ulosis, the patient failed to respond. A clonal myeloid disorder which was initially suppressed by T-cell immunosurveillance evolved after treatment w ith anti-thymocyte globulin. Although the coexistence of sarcoidosis remain s a possibility, the lack of supportive clinical evidence of sarcoidosis, t he abnormal appearances of the bone marrow, together with the failure to im prove on high-dose steroid favour the clonal myeloid disorder as the sole p athology.