Gastrointestinal T cell lymphoma: Predominant cytotoxic phenotypes, including alpha/beta, gamma/delta T cell and natural killer cells

Gastrointestinal T cell lymphoma (TCL) is a rare subset of peripheral TCL, presenting with or without cytotoxic phenotype, a history of coeliac diseas e (CD) and enteropathy. However, CD is rare in Japan. Here, we describe the clinicopathological features of 18 Japanese cases. Lesions were found in t he small intestine (n=13), stomach (n=3) and colon (n=2). Seven patients pr esented with enteropathy but none had a history of CD. Lymphomas appeared a s ulceration (n=11), tumour formation (n=6), or polypoid growth (n=1). Hist ologically (REAL classification), neoplastic lesions were composed of intes tinal type T cell lymphoma (ITCL, n=13, including one case with NK type), a naplastic large cell (ALCL, n=2), adult T cell leukaemia/lymphoma (ATLL, n= 2), and lymphoblastic type (n=1). Epstein Barr virus infection was detected by EBER-1 in situ hybridization in 6 of 11 cases with ITCL but not in the other types. ALCL expressed CD30. CD56 was expressed in 3 of 11 cases of IT CL but not in other types. Among the 10 examined cases, 8 were alpha beta T cell type [CD2+, CD3+, T cell receptor (TCR)delta-1-, beta F1+], one was g amma delta T cell type [CD2+, CD3+, TCR delta-1+, beta F1-], and the remain ing case expressed natural killer (NK) cell type [CD2+, CD3-, CD56+, TCR de lta-1-, beta F1-]. Among the 8 examined cases, 3 expressed CD103 molecule, which was associated with extrathymic T cells of intraepithelial lymphocyte s. All cases except ATLL expressed the cytotoxicity-associated molecule of TIA-1, and 11 of 14 TIA-1 positive cases expressed activated cytotoxic mole cules of perforin, granzyme B, and/or Fas ligand. Despite the morphological , genetic and phenotypic heterogeneity, prognosis was poor, and 11 of 13 pa tients with small intestinal lesions died albeit appropriate treatment, but 3 of 4 patients with gastric or colonic lesions were still alive. The main cause of death was intestinal perforation. The latter might be due to the site specificity of small intestine and tumour cytotoxicity.