CD56 positive diffuse large B-cell lymphoma: a case report and literature review.

CD56 positive B-cell lymphoma is very rare. We experienced a case of CD56 positive diffuse large B-cell lymphoma, occurred in a young child. A 5-year-old girl complained with snoring and open mouth breathing. No any abnormality in laboratory or physical examination was present, except enlarged both tonsils. Bilateral tonsillectomy was performed. Cut sections of right tonsil showed a 2 cm size, solid mass. On microscopically, large monomorphic lymphoid cells were diffusely proliferated and showed positivity for CD20 and CD56 and negative for Epstein-Barr virus (EBV) polymerase chain reaction (PCR). Monoclonality was observed on immunoglobulin heavy chain gene rearrangement. This is a unique case with incidentally found and occurred in a young child.