Giant Cellulitis-Like Sweet Syndrome Masquerading As Cellulitis and Shingles: A Case Report and Literature Review.

Sweet syndrome (SS) is also known as acute febrile neutrophilic dermatoses. Clinically, SS features fever, arthralgias, and the sudden onset of an erythematous rash. The morphologies of skin lesions in SS are heterogenous, varying from papules, plaques, and nodules to hemorrhagic bullae, which sometimes makes the diagnosis of SS more challenging. We report a 62-year-old obese male with a history of chronic myeloid leukemia in remission for 10 years who presented with a rash for five days. The patient reported prodromal flu-like symptoms with subjective fever, malaise, cough, and nasal congestion followed by a sudden onset, painful, non-pruritic rash. The rash was associated with bilateral hip arthralgias and abdominal pain. The patient denied any recent travel, exposure to sick contacts, or the use of any new medications. Physical examination showed a well-demarcated, non-blanching, confluent, erythematous plaque involving the bilateral buttocks and extending to the lower back and flanks with coalescent "juicy"-appearing plaques and flaccid bullae. No oral or mucosal involvement was noted. Laboratory investigations revealed mild leukocytosis, elevated inflammatory markers, and acute kidney injury. The patient was started on antibiotics given the cellulitis-like skin lesions, leukocytosis with neutrophilia, and elevated inflammatory markers. Dermatology was consulted, who attributed the patient's rash to shingles and recommended initiating acyclovir and obtaining a skin biopsy. However, the patient's rash and arthralgias worsened with anti-viral treatment while awaiting pathology results. Antinuclear antibodies, complement, human immunodeficiency virus, hepatitis panel, blood cultures, and tumor markers were all negative. Flow cytometry showed no evidence of hematopoietic neoplasms. The skin punch biopsy revealed dense neutrophilic infiltration in the dermis with no evidence of leukocytoclastic vasculitis, consistent with acute neutrophilic dermatoses. The diagnosis of giant cellulitis-like Sweet syndrome was established, and the patient was started on prednisone 60 milligrams daily. His symptoms improved promptly with steroid treatment. Our case suggests that SS can camouflage a wide spectrum of diseases, including cellulitis, shingles, vasculitis, drug eruptions, leukemia cutis, and sarcoidosis, which emphasizes the importance of keeping a high index of suspicion for SS when assessing the clinical constellations of fever, neutrophilia, and erythematous plaques suggesting atypical cellulitis. Approximately 21% of Sweet syndrome is associated with malignancy. Sweet syndrome can precede, concur with, or follow the onset of malignancy. Due to the lack of a systematic approach to patients with SS, under-investigation and diagnostic delays are common. Therefore, further screening and continuous monitoring in patients with SS becomes especially important in facilitating the early detection of a potential underlying malignancy and assists in initiating adequate therapy.