Interfollicular Hodgkin's disease: an uncommon pattern that may cause diagnostic difficulty.

Interfollicular Hodgkin's Disease is characterised by reactive follicular hyperplasia with involvement of the interfollicular area of lymph node by Hodgkin's lymphoma. It represents a peculiar pattern of focal involvement of lymph node and does not constitute a classical subtype. Its importance rests in the fact that it can be misinterpreted as one of the many causes of reactive hyperplasia of lymph node and not as Hodgkin's disease. Eleven cases of interfollicular Hodgkin's disease were diagnosed in a period of five years. Majority of the patients were less than twenty years and all had localised lymphadenopathy. Lymph node biopsy showed follicular hyperplasia with expanded interfollicular area. Careful search of the interfollicular area showed infiltration by inflammatory cells and scattered Reed-Sternberg and Hodgkin's cells. Immunohistochemistry with CD 15 and CD 30 highlighted the atypical cells. This report emphasises on the problems in diagnosis of interfollicular Hodgkin's disease.