Histiocytoid Sweet syndrome harboring an isocitrate dehydrogenase 1 mutation: A case report and retrospective analysis of 29 cases of histiocytoid Sweet syndrome.

Histiocytoid Sweet syndrome (HSS) is a rare histopathologic variant of Sweet syndrome that demonstrates dermal and/or subcutaneous infiltrate with a prominent component of myeloid cells resembling histiocytes. It has been known to occur in association with hematologic neoplasms, including myelodysplastic syndrome (MDS) and acute myelogenous leukemia, but whether it confers an increased risk of such neoplasms is controversial. Here, we describe a case of a HSS that led to the diagnosis of MDS with an isocitrate dehydrogenase 1 (IDH-1) mutation and a corresponding study looking for additional cases of IDH-1 mutations in biopsies of histiocytoid and conventional Sweet syndrome.