S-100 positive multicentric reticulohistiocytosis – report of a rare case with brief review of literature

Background: Multicentric reticulohistiocytosis (MRH) is a rare histiocytic proliferative disorder involving skin, mucosa and joints. Diagnosis is confirmed by histopathological examination. Case Report: A 45 year old patient presented with non-pruritic papules over the body and multiple joint pains. Histopathologically, the lesion was composed of oncocytic macrophages and multinucleate giant cells with abundant, eosinophilic and granular cytoplasm with ground glass appearance. Immunohistochemical expression for CD-68 and S-100 was seen . Conclusion: We describe a case of MRH along with brief review of literature with unusual immunohistochemical expression of S-100 protein which is reported negative in majority of previously presented cases, however CD68 positivity confirmed the non-langerhans cell origin.