TCL-362: Clinicopathological Profile of Peripheral T-Cell Lymphoma-NOS and Angioimmunoblastic T-cell Lymphomas

Context: Peripheral T-cell lymphomas derived from the mature T-cells are a heterogeneous group with varying biological and clinical behaviour. Objective: We analysed the epidemiological, clinical, histomorphological, immunophenotypic, and mutational characteristics of PTCLs in our centre. Design: This was a retrospective study including all cases of PTCL from 2015 to 2019 retrieved from the archive of Department of Pathology, AIIMS, New Delhi. The cases were reclassified according the WHO 2016 classification. Additional immunohistochemistry (PD1, ICOS, Bcl6 and CD10), EBERish, and mutational studies for IDHR172 and RHOA G17V) were done in cases diagnosed as PTCL-NOS and AITL. The clinical profile was correlated with the above factors and the prognostication index. Results: Of the total 441 lymphoma cases diagnosed of T-cell lineage, 35.37% were of the precursor type, and the rest were mature T-cell lymphomas. A male predominance was noted. PTCL-NOS was the most common subtype among the mature type (n=76; 17.23%) followed by ALCL, ALK+ (n=70; 15.87%), extranodal NK-/T-cell lymphomas (n=58, 13.15%), and AITL (n=16; 3.63%). They were dominant in the adult age (19–65 years, n=207), followed by pediatric and adolescents (n=43) and elderly (n=35) populations. The primary site of involvement was a mixture of nodal (n=138) and extranodal (n=147). The patients presented in advanced stages with a mean IPI score of 3/5. High LDH levels with direct Coombs test positivity was noted among AITL patients. With the help of immunohistochemistry, a few of the diagnosed PTCL-NOS were reclassified as AITL, and one of the diagnosed AITL was reclassified as PTCL with TFH phenotype. A few of the diagnosed AITL cases immunonegative for EBV-LMP1 proved their causal relationship with EBERish positivity. An overall mean survival of 20 months was noted among 30 cases with a maximal follow up of 3 years. Conclusions: A higher prevalence of immature cell neoplasm and ALCL was noted among the Indian population. Though morphologically there may be an overlap in the diagnosis among the various PTCL subtypes, immunohistochemistry and molecular studies can help in reaching the definite diagnosis. Funding: Thanks to the Science Engineering Research Board (EEQ/2016/402, ECR /2015/452) and All India Institute of Medical Science Research Section (A-653).