Histiocytic necrotizing lymphadenitis:a clinicopathological and immunohistochemical study of 24 cases

Objective To study the clinicopathological and immunohistochemistry features of 24 cases histiocytic necrotizing lymphadenitis (HNL). Methods The clinicopathological features of 24 cases HNL were analyzed. Immunophenotyping and detection of apoptotic DNA fragments were performed using SP and TUNEL methods respectively. Results There were 20 females and 4 males, with age ranged from 18~46 years (mean 29 years). Superficial lymph nodes are primarily involved, especially the cervical lymph nods swelling with fever. Histologically variable sized discrete or confluent nodules were seen in the paracortex, which were composed of proliferative pleomorphic histiocytes, transformed lymphocytes and karyorrhectic debris. Immunohistochemistry revealed CD3(+) and CD45RO(+)for lymphocytes, CD68(+)for histiocytes, and no expression for CD15, CD30 and CD20 in the lesion. Conclusions HNL is often mistaken for malignant lymphoma. A backgroud of reactive lymphadenopathy, prominent karyorrhexis and pathy nodal involvement in the form of non-expansive patchs are the important points of differential diagnosis. The presence of pleomorphic histiocytes, transformed T-cells, and karyorrhectic debris in the biopsy of lymph nodes, together with thd absence of neutrophils support the diagnosis of HNL.