The cutaneous lesions of Kikuchi's disease: a comprehensive analysis of 16 cases based on the clinicopathologic, immunohistochemical, and immunofluorescence studies with an emphasis on the differential diagnosis.

Kikuchi's disease is a self-limited necrotizing lymphadenitis that is characterized by cervical lymphadenopathy and fever. Although it has been reported that some patients with Kikuchi's disease have cutaneous manifestations, the specific skin changes of patients with Kikuchi's disease have not been fully described. We report here on 16 patients of Kikuchi's disease with cutaneous manifestations. We reviewed the clinical histories of the patients who underwent lymph node and skin biopsies. Immunohistochemistry, immunofluorescence, and Epstein-Barr virus-encoded RNA (EBER) in situ hybridization were performed. The patients ranged in age from 7 to 39 years and included 4 males and 12 females. All the patients had histiocytic necrotizing lymphadenitis. The clinical impression was variable according to the various cutaneous manifestations. The skin biopsies showed vacuolar interface changes (12/16; 75.0%), necrotic keratinocytes (11/16; 68.8%), superficial (16/16; 100.0%) and deep (9/16; 56.3%) lymphohistiocytic infiltration, karyorrhexis (16/16; 100.0%), deposition of mucin (5/16; 31.3%), and panniculitis (9/15; 60.0%). Based on immunohistochemistry, the infiltrating cells were predominantly CD68 and CD163-positive histiocytes and CD3-positive T lymphocytes. Of the 16 patients, 13 (81.3%) had a slight predominance of CD8-positive lymphocytes. Direct immunofluorescence staining and EBER in situ hybridization were all negative. Although the clinical and histopathologic findings are very heterogenous, the presence of a lymphohistiocytic infiltration with nonneutrophilic karyorrhexis helps to make the diagnosis of Kikuchi's disease with skin involvement.