Abstract

Sweet syndrome (SS), acute febrile neutrophilic dermatosis, is an uncommon reactive skin condition that can be associated with myeloid disorders. The infrequently reported subcutaneous Sweet syndrome (SSS) is a rare variant of SS that is almost exclusively associated with underlying myeloid disorders. We describe a 61-year-old woman with myelodysplastic syndrome with excess blasts-2 (MDS-EB-2) who developed SSS. Ten months after her MDS-EB-2 diagnosis and treatment, she presents with afebrile cellulitic skin lesions followed by multiple non-tender nodules on her left knee and bilateral forearms. Biopsy of the lesion is performed to differentiate possible leukemic infiltrate, drug-induced dermatitis, and infectious skin disease. The lesion shows septal and lobular neutrophilic panniculitis with dermal sparing. The infiltrate comprises predominantly mature neutrophils with occasional leukocytoclasis. No blasts, vasculitis, granulomatous inflammation, or microorganisms are seen on H&E and special stains (Grocott, Ziehl-Neelsen and PAS). With her history of MDS, and after exclusion of infection, drug reaction, and cutaneous leukemic infiltrates, the diagnosis of SSS is made. Any variant of SS is commonly seen and often precedes underlying malignancies. This reactive cutaneous lesion can be a sign of undiagnosed malignancy or a cancer recurrence in a patient with previous malignancy. In addition to its association with underlying myeloid disorder, SS may also be induced by chemotherapy or other medications. Based on the histological findings with clinical correlation, the exclusion of infection, drug reaction, and leukemic infiltrate, neutrophilic panniculitis in a patient with MDS is most compatible with SSS.