Acute febrile neutrophilic dermatosis (Sweet's syndrome) in a patient with hairy-cell leukemia

A case of hairy-cell leukemia that started with cutaneous lesions similar to those of acute febrile neutrophilic dermatosis (Sweet's syndrome) is reported. The patient had leukopenia and a recurrent eruption for a year prior to the diagnosis of the hematologic disorder. Bone marrow examination eventually demonstrated characteristic "hairy" cells with tartrate-resistant, acid-phosphatase activity. Biopsy of a cutaneous lesion suggested an abscess showing a dense neutrophilic dermal infiltrate with perivascular predilection. The findings of IgA, IgM, C3, and fibrinogen in vessel walls by immunofluorescence and vascular disruption by electron microscopy contribute additional evidence for an immunologic determinant in this instance of Sweet's syndrome. It is known that neutrophilic infiltrates of Sweet's syndrome may have a variety of clinical presentations. This is the second case of hairy-cell leukemia with which Sweet's syndrome was associated.