Granzyme B-positive primary gastric T-cell lymphoma: Gastric T-cell lymphoma with the possibility of extrathymic T cell origin

A case of primary gastric T-cell lymphoma, which was positive for granzyme B, is reported. The patient was a 47-year-old Japanese female who complaine d of a dull upper abdominal pain. Radiographic and endoscopic examinations revealed an ulcerative infiltrative lesion in her stomach. Following the co nfirmation of a high-grade malignant lymphoma, a distal gastrectomy with re gional lymph nodal dissection was performed. The histology of the gastric l esion revealed a malignant lymphoma of the diffuse pleomorphic type without lymph nodal involvement. Immunohistochemistry revealed that the tumor cell s were positive for LCA, CD3, TIA-1 and granzyme B, but were negative for C D4, CD8, CD56, CD30, L-26, EMA, TCR alpha/beta and TCR gamma/delta. Because the tumor cells showed T cell nature with cytotoxic activity proved by TIA -1 and granzyme B, and without evidence of further maturation of T cell, a malignant lymphoma originating from extrathymic-derived T cells was suggest ed.