OBJECTIVETo clarify clinical and morphological features and immunophenotype of T lymphoblastic lymphoma/leukaemia (T-LBL/ALL) and to further improve the knowledge and diagnostic accuracy for T-ALL/LBL.

METHODS128 cases of T-LBL/ALL were analyzed for the clinical features, morphology, immunophenotype and TCR gene rearrangement using routine eosin and haematoxylin stain, immunohistochemistry and polymerase chain reaction combining with the clinical findings.

RESULTSIn 128 cases of T-LBL/ALL, there were 94 male and 34 female. The ratio of male/female was 2.8:1. The age of patients ranged from 4 to 88 years, with an average of 27 years and a median of 22 years. Lymph nodes and extranodal areas were involved in 58/128 and 27/128 cases of T-LBL/ALL, respectively. The other 43 cases had involvement of both nodal and extranodal areas. Cervical node and mediastinum were involved in 74 cases and 43 cases, respectively. Diffuse growth pattern of tumor cells was predominant. Nodular growth pattern was seen only in a few cases. Most cases composed of small to medium-sized lymphoblasts, and other 7 cases showed a composition of large lymphoblasts. Tumor cells expressed TdT in 121/128 (94.5%) cases, CD34 in 48/98 (49.0%) cases, CD3 in 78/108 (72.2%) cases, CD7 in 104/108 (96.3%) cases, CD43 in 56/63 (88.9%) cases, CD79a in 5/70 (7.1%) cases, CD10 in 25/76 (32.9%) cases, CD99 in 58/60 (96.7%) cases and Pax-5 in 4/91(4.4%) cases. All of the cases were negative for MPO. A follow up data, ranging from 1 to 53 months, was obtained in 51/128 (39.8%) patients. The over all survival rate was 68.6% and the median survival time was 12 months. Under a similar condition of carrying a positive staining result on CD3 in tumor cells, there was a statistically significant difference between patients in the group of over 30 of age and that with the age ranging from 11 to 30. Patients associating with a CD10 positive staining of tumor cells showed also a shorter survival period. In addition, there were 4 out of 5 cases showing the presence of TCR gene rearrangement.

CONCLUSIONST-LBL/ALL are aggressive in behavior, associating mainly with enlarged cervical lymph nodes and masses in the mediastinum, occurring predominantly in children and young adults. Although small to medium-sized tumor cells with diffuse pattern were found in most cases, however, large-sized tumor cells and nodular pattern could also be obtained in a few cases. Immunohistochemistry staining particularly adoption of CD7, Pax-5, TdT, CD34 and Ki-67 stainings in combination are helpful of making a diagnosis for T-LBL/ALL. Analysis of TCR gene rearrangement will be helpful for the diagnosis of a few difficult cases.