Primary Eosinophilic Granuloma of Lymph Node: Case Report of an Enigmatic Disease

Eosinophilic granuloma with solitary involvement of a lymph node is very rare. It occurs mainly in children. We present a rare case report of an adult male with primary eosinophilic granuloma of a lymph node, which had regressed following fine-needle aspiration cytology (FNAC) and again to reappeared after 1 month. Eosinophilic granuloma is most likely to be a reactive process directed against one or more yet unidentified agents. Isolated lymph node involvement in Langerhans cell histiocytosis still remains an enigmatic entity, as its pathogenesis is not fully unraveled. Careful morphological examination and immunohistochemistry studies will help to arrive at the correct diagnosis of this rare entity. This case is presented due to its rarity, uncommon age group of presentation, and histology with completely effaced lymph node architecture and regression episode following FNAC.