Necrosis in lymph nodes and their differential diagnoses: application of reticulin staining.

This study aimed to enhance the histopathological diagnosis of necrotic lymph node specimens. A chart review was conducted, revealing that the most common causes of lymph node necrosis were Kikuchi disease (33%), granulomatous inflammation (25%), metastasis (17%), and lymphomas (12%). Histological analysis of necrotic tissue in 333 specimens demonstrated significant differences between the four diseases. The necrotic tissue of Kikuchi disease was amorphous, and hypercellular, and exhibited karyorrhexis and congestion. Granulomatous inflammation presented amorphous necrotic tissue with a nodular-like pattern. Metastasis exhibited heterogeneous morphology that varied between cancer types. Lymphomas displayed extensive necrosis with ghost cells, congestion, and bubbles. Reticulin staining patterns also differed between diseases. Kikuchi disease and lymphomas exhibited preserved reticular fiber networks in the necrotic tissue, resembling the viable tissue. Granulomatous inflammation and metastasis showed disrupted reticular fiber networks in the necrotic tissue. Based on these findings, histological features and reticulin staining patterns can aid in diagnosing Kikuchi disease, granulomatous inflammation, metastasis, and lymphomas in necrotic lymph node specimens.