OBJECTIVETo study the clinicopathologic features and prognostic significance of ZAP-70 protein expression in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).

METHODSThe histologic features of 52 cases of CLL/SLL with lymph node and/or bone marrow biopsies performed were retrospectively reviewed. Immunohistochemical study using EliVision for ZAP-70 protein was adopted.

RESULTSThe lymph nodes of the 12 cases studied showed effacement of the nodal architecture and was replaced by a monotonous infiltration of small lymphoid cells. Among them, proliferation centers were identified in 6 cases. Similar morphologic pattern was seen in the 40 bone marrow biopsy samples, but no proliferation center formation obtained. The infiltration pattern of tumor cells in the bone marrow were further subdivided into nodular (n = 9), interstitial (n = 3), mixed (n = 9) and diffuse types (n = 19). There was no significant difference found on survival rates between the diffuse infiltration and non-diffuse infiltration groups (Fisher's exact test, P = 0.199). ZAP-70 protein was mainly located in the cytoplasm and nuclei of lymphoma cells. There were 21 cases (40.4%) positive for ZAP-70 and among them, 11 died of this disease or the related infections. On the other hand, ZAP-70 was negative in 31 cases (59.6%) and only 4 of them died of this disease or related infections. The overall survival in ZAP-70-negative group was higher than that of the ZAP-70-positive group (59 months versus 39 months, chi(2) = 6.991, P = 0.008). Follow-up information was available in 51 patients. Among the 21 dead cases, 15 died of CLL/SLL or the related infection.

CONCLUSIONA positive expression of ZAP-70 protein in CLL/SLL suggests a poor prognosis.