Aberrant expression of multiple T cell markers on diffuse large B cell lymphoma: a case report.

BACKGROUND: Aberrant T cell antigen expression has been well documented in diffuse large B cell lymphomas. However, co-expression of multiple T cell antigens including CD3, which has been considered a specific marker for T cells is extremely rare. Awareness about such aberrant expression is important so as not to misdiagnose or wrongly classify a lymphoma. The aim of this article is to report such a case.

CASE PRESENTATION: A 68-year-old postmenopausal lady, diabetic and hypertensive, presented with an axillary lump of one week's duration. There was no other relevant medical history. Ultrasonography revealed multiple hypoechoic cystic lesions varying in size from 3.9 to 4.2 cm3 . Aspiration was suggestive of an infective pathology. Excision biopsy of the mass was diagnosed as diffuse large B cell lymphoma with aberrant T cell antigen expression. She received 4 cycles of chemotherapy after which she was lost to follow-up.

CONCLUSION: The case presented as a diagnostic dilemma for the pathologist. The predicament lies in classifying it as a B cell lymphoma with an aberrant expression of T cell markers versus a T cell lymphoma with an aberrant B cell marker expression which has a significant implication on the treatment offered. This can be solved by looking at the expression of the B cell specific transcription factors. The key to diagnosis lies in the knowledge of their existence and the application of a panel of markers.