Kikuchi's histiocytic necrotizing lymphadenitis. Diagnosis by fine needle aspiration.

Two cases of Kikuchi's histiocytic necrotizing lymphadenitis diagnosed by fine needle aspiration (FNA) of enlarged lymph nodes are reported. The FNA smears contained randomly activated lymphoid cells, necrotic debris, karyorrhectic cells and prominent histiocytes, suggesting the presence of reactive lymph nodes. The true nature of the lesions was evident from the examination of cell block sections prepared from tissue fragments in the aspirates, which preserved the architectural relationships of the different cell types. The same patterns were found in retrospectively and subsequently examined excised lymph nodes from these cases. The differential diagnosis of this entity, which may simulate a malignant lymphoma because of the presence of large numbers of activated lymphoid cells, is discussed and the value of preparing FNA cell blocks is emphasized. Though this rare benign disease may be suspected clinically in the more typical cases, such as young women with cervical lymphadenopathy, fever, neutropenia and otherwise excellent condition, the diagnosis cannot be made without a lymph node biopsy, which FNA may be able to provide in some instances.