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.