A Case of Histiocytoid Sweet Syndrome without a Hematologic Disorder

Kong, Tae Seok; Han, Tae Young; Lee, June Hyunkyung; Son, Sook Ja

Abstract

Histiocytoid Sweet syndrome (HSS) is a recently described rare variant of acute febrile neutrophilic dermatosis. HSS is clinically characterized by painful inflammatory plaques or nodules with high fever and neutrophilia. About 20% of HSS patients also have an associated malignancy, most commonly of hematologic origin. Histopathologically, HSS is characterized by dense histiocytic infiltration with prominent upper dermal edema, and little neutrophil infiltration. A 69-year-old female presented with a 1-week history of painful erythematous plaques on both elbows accompanied by fever. She was diagnosed with acute pyelonephritis and treated with ciprofloxacin for 2 weeks. Routine laboratory tests showed elevated white blood cell count (predominantly neutrophils), erythrocyte sedimentation rate, C-Reactive Protein, and a mildly elevated liver function test. Peripheral blood smears were normal. Histopathologic examination showed papillary dermal edema and diffuse interstitial infiltration of histiocytoid cells. Immunohistochemical studies revealed that the histiocytoid cells were positive for CD 68 and myeloperoxidase. After treatment with systemic glucocorticoids, the skin lesions and fever gradually resolved. Based on the clinical and histopathologic examination, we diagnosed HSS with no evidence of a hematologic disorder. Herein, we report an unusual case of HSS without associated bone marrow dysplasia.