Histiocytoid Sweet Syndrome: A Distinct Entity Within the Spectrum of Myeloid Dermatoses

Histiocytoid Sweet syndrome (H-SS) is a variant of Sweet syndrome characterized by a dermal infiltrate of immature myeloid cells with histiocytoid morphology rather than mature neutrophils. These cells express myeloid markers including myeloperoxidase, lysozyme, CD15, and CD13. H-SS has been associated with hematologic malignancies and demonstrates higher relapse rates compared with classic Sweet syndrome. This review synthesizes current evidence on the clinicopathologic features, immunophenotype, disease associations, and treatment of H-SS, and examines its position within the broader spectrum of myeloid cutaneous infiltrates.