The correct answer is Sweet’s syndrome (choice “a”), also known as acute febrile neutrophilic dermatosis. Read on for a discussion of this condition.
Mastocytosis (choice “b”) can present with solitary lesions (“mastocytoma”), but biopsy would have shown a marked increase in mast cells, not the mature polymorphonuclear leukocytes seen in this biopsy. Pyoderma gangrenosum (choice “c”) lesions eventually ulcerate, and biopsy would have revealed a mixed infiltrate instead of the purely neutrophilic one seen. Cellulitis (choice “d”) would have manifested acutely, quickly becoming suppurative, in contrast to the persistence seen with this lesion.
Sweet’s syndrome was first described in 1964 and has since been organized into three basic categories: the classic type, often idiopathic since most cases are of unknown origin; malignancy-associated, typically hematologic (eg, myelogenous leukemia); and drug induced, which was first described in association with sulfa-trimethoprim.
The classic presentation can be triggered by, among other things, upper respiratory infections, pregnancy, and inflammatory bowel disease—as in our patient, whose lesion is quite typical. Arguably the most significant association is with a malignancy, a search for which is undertaken when other possible triggers are absent.
The gold standard for treatment of Sweet’s syndrome is systemic corticosteroids, but other drugs have been used with success, including colchicine and dapsone. This patient is being successfully treated with topical clobetasol cream under occlusion, selected because her disease is very limited. Complete blood count and manual differential diagnosis failed to show any evidence for leukemia.