Extranodal involvement in lymphoma – A Pictorial Essay and Retrospective Analysis of 281 PET/CT studies

OBJECTIVES The aim of this study is to evaluate the role of PET-CT in identification of different patterns of extranodal involvement in Hodgkin's disease (HD) and Non-Hodgkin's Lymphoma (NHL) and to enlist the common sites of extranodal involvement in each histological type and compare our results with the existing literature. METHODS In this retrospective study of 281 cases of lymphomas of various histologies, we illustrate the spectrum of PET/CT features of extranodal lymphoma (ENL) of commonly involved organs and compare our result with the literature. RESULT Extranodal appearance in lymphoma is strikingly varied. Diffuse large B cell lymphoma (DLBCL) is the commonest histological subtype and gastrointestinal tract is the commonest anatomical subsite in NHL. Skeletal system is the commonest site for involvement in HD. CONCLUSION A broad spectrum of extranodal organs is involved in various subtype of lymphoma which can be depicted in PET-CT in the most appropriate manner. Familiarity with the pattern of involvement is essential for comprehensive management.