Mantle cell lymphoma (MCL) is a rare and aggressive non-Hodgkin's B cell lymphoma characterized by the translocation t(11;14) (q13;32) and overexpression of CCND1. MCL is immunophenotypically identified as CD20+, CD5+, CyclinD1+, CD43+, CD10-, BCL6-, and CD23-. It is often distinguished from B cell lymphomas of germinal center cell origin by the absence of CD10 expression. Here we report the unique clinicopathologic features of a patient with CD10+ MCL with gastrointestinal involvement and review current literature identifying this unique immunophenotype.