INTRODUCTION
Sweet syndrome (SS), first described in 1964, is a disease constellation of pyrexia, neutrophilic leukocytosis, tender erythematous papules/nodules/plaques, and a diffuse papillary dermal infiltrate of mature neutrophils.1 Three common subtypes of SS have been identified: classic (idiopathic), malignancy-associated, and drug-induced.1 The drug-induced form of SS most often arises with the usage of granulocyte colony-stimulating factor (G-CSF) medications, such as filgrastim, with fewer reports associated with pegfilgrastim, but has also been associated with all-trans-retinoic acid, oral contraceptives, antiepileptics, antihypertensives, antibacterials, and vaccines.
CASE REPORT
A 45-year-old Caucasian female presented with fever (39.2° C), chills, and red spots on her right upper arm and right elbow as well as faint red spots on her left arm appearing 3 days prior. White blood cell count was 21.9 x 109/L. Her past medical history included grade 3 invasive ductal carcinoma with BRCA gene mutation (on chemotherapy), dermatomyositis (on hydroxychloroquine), necrotizing fasciitis subsequent to cesarean section, and tobacco abuse. Her last chemotherapy administration consisted of doxorubicin, cyclophosphamide, and pegfilgrastim (6 mg dose subcutaneous once) 14 days prior.
On dermatologic examination, over the arms, there were semi-firm subcutaneous plaques/nodules, some with overlying erythema (Figure 1). The morphology and clinical picture were concerning for infection (fungal favored over bacterial) versus Sweet syndrome secondary to pegfilgrastim administration. A punch biopsy of the right arm demonstrated skin with an unremarkable epidermis. Within the superficial and deep dermis, extending into the subcutaneous tissue, there was a mild perivascular and interstitial mixed inflammatory infiltrate composed of lymphocytes and neutrophils (Figure 2A and 2B). Histochemical stains for fungus (GMS) and acid-fast bacteria (Fite) were negative. Based upon histology, the differential
On dermatologic examination, over the arms, there were semi-firm subcutaneous plaques/nodules, some with overlying erythema (Figure 1). The morphology and clinical picture were concerning for infection (fungal favored over bacterial) versus Sweet syndrome secondary to pegfilgrastim administration. A punch biopsy of the right arm demonstrated skin with an unremarkable epidermis. Within the superficial and deep dermis, extending into the subcutaneous tissue, there was a mild perivascular and interstitial mixed inflammatory infiltrate composed of lymphocytes and neutrophils (Figure 2A and 2B). Histochemical stains for fungus (GMS) and acid-fast bacteria (Fite) were negative. Based upon histology, the differential
