Clinical Molecular Diagnosis of T-Cell Receptor Gene Rearrangement in Thai Patients.

Thirteen Thai patients, seven with pathologic diagnosis of T-cell lymphoma, four with clinical and/or pathological suspicion of T-cell lymphoma, one with lymphadenitis and one with chronic hypertrophic tonsillitis, were investigated for T-cell receptor gene rearrangement (TCR-GR) by polymerase chain reaction (PCR). Clonal TCR-GR was demonstrated in each T-cell lymphoma whereas polyclonal TCR-GR was found in the rest of the patients, including the four cases that were suspected of T-cell lymphoma.

Aim: To identify T-cell receptor gene rearrangement in malignant lymphoma in Thai patients.

Material and method: Thirteen specimens of formalin-fixed, paraffin-embedded tissue were collected from Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University. After conventional morphological evaluation and immunohistochemical studies, DNA in each specimen was extracted from 10μm thick paraffin sections using QIAamp DNA mini kit (QIAGEN) for TCR-GR analysis by multiplex PCR. Two pairs of primers were selected for Vγ11 (VγI), Vγ101(VγIII/IV), Jγ12(Jγ1/2) and Jp12(JPγ1/2). DNA of the four cases suspected of malignant lymphoma were repeated by using IdentiClone™ TCRG Gene Clonality Assay kit (InVivoScribe Technologies).

Results: According to the WHO classification (2001), the seven cases of T-cell lymphoma were angioimmunoblastic type (3 cases) and unspecified type (4 cases). All cases showed monoclonal TCR-GR. Only one of the four cases suspected of T-cell lymphoma was doubtful for nasal NK/T-cell lymphoma while the others were suspected clinically. All of these four cases and the two reactive conditions revealed polyclonal TCR-GR. After using IdentiClone™ kit twice, the four cases suspected of T-cell lymphoma still showed polyclonal TCR-GR.

Conclusion: The molecular analysis of TCR-GR performed in thirteen cases demonstrated the monoclonal TCR-GR in all seven cases of T-cell lymphoma and polyclonal TCR-GR in the four cases suspected of T-cell lymphoma and the two cases of reactive condition. Therefore, this technique is very useful to confirm the diagnosis of T-cell lymphoma and to provide information for further management in patients suspected of malignant lymphoma.