OBJECTIVETo recognize the importance of analyzing the result of immunohistochemical staining correctly.

METHODReview of the three misdiagnosed cases lymphoma and exploring the causes of misdiagnosis through reviewing their clinics, histopathology and immunohistochemistry.

RESULTSCase 1 of lymphocyte rich classical Hodgkin's lymphoma (LRCHL) was misdiagnosed as follicular lymphoma (FL) initially, the RS cells were overlooked morphologically and wrongly determined BCL-2 and CD20-positive cells as tumor cells immunohistochemically; also once misdiagnosed as nodular lymphocyte predominant Hodgkin's lymphoma (NLPHL) because the CD20-negative RS misjudged cells as the positives. Case 2 of AML tumor cells expressed TdT, CD7 and CD43 unspecifically, which misdiagnosed as T-cell lymphoblastic lymphoma (T-LBL). Case 3 of type B1 thymoma was misdiagnosed as T-LBL, because CK wasn't expressed satisfactorily resulting in neglecting neoplastic epithelial cells, and lymphocytes in the background were TdT and CD99-positive.

CONCLUSIONThe diagnosis of lymphoma should be based on morphology, immunohistochemistry, clinics, and genetics. Moreover, the correct judgment of immunohistochemical staining is essential to make right diagnosis.