Clinical mimics of lymphoma.

Lymphadenopathy is a common clinical finding and is frequently benign. Warning signs suggestive of a malignant etiology include lymph nodes >2 cm in size, supraclavicular location, and generalized lymphadenopathy associated with hepatosplenomegaly or systemic symptoms. A metastatic solid tumor is always in the differential diagnosis of localized lymphadenopathy, particularly in older individuals. In the case of more generalized lymphadenopathy, in addition to the more common lymphomas, benign etiologies as well as benign and atypical lymphoproliferative disorders need to be considered. Benign etiologies of lymphadenopathy can include infections, autoimmune disorders, drug hypersensitivity reactions, sarcoidosis, and amyloidosis. Rare but benign lymphoproliferative disorders include Kikuchi's disease, Rosai-Dorfman disease, and progressive transformation of germinal centers. Atypical lymphoproliferative disorders that bear close surveillance for evolution to a more aggressive malignancy include Castleman's disease, lymphomatoid granulomatosis, and lymphomatoid papulosis. Previously considered in this category but now classified as a true lymphoma is angioimmunoblastic lymphadenopathy with dysproteinemia. Physicians need to be aware of all of these disorders when evaluating suspicious lymphadenopathy, while also considering the more common lymphomas and leukemias.