A case of histiocytic necrotizing lymphadenitis diagnosed by a skin biopsy

A 31-year-old man presented with a high fever, cervical lymphadenopathy, and nail-sized indurated erythematous lesions on his face, neck, upper extremities, and trunk. Histopathological examination of a skin biopsy revealed vacuolar interface changes, necrotic keratinocytes, and superficial and deep dermal infiltration of histiocytes and lymphocytes with nonneutrophilic karyorrhexis around the vessels and adnexal structures. Immunostaining showed that the infiltrating cells were predominantly CD68-positive histiocytes and CD3-positive T lymphocytes. The number of CD8-positive lymphocytes was larger than that of CD4-positive lymphocytes. Without any treatment, his condition and skin lesion improved a week later. Based on the clinical and histological findings, the skin disease was diagnosed as the cutaneous manifestations of histiocytic necrotizing lymphadenitis (HNL), which is a self-healing lymphadenopathy. HNL mainly affects young adults and is clinically characterized by cervical lymphadenopathy and high fever. Histopathological cutaneous findings in HNL are similar to those of a lymph node lesion. Therefore, it is important to recognize the cutaneous lesion of HNL, so that more invasive diagnostic procedures, such as lymph node biopsy, can be avoided. Histological analysis of a skin biopsy helps to make the diagnosis of HNL with skin involvement.