Mantle cell lymphoma (MCL) is a B cell lymphoma with four morphologic variants recognized by the current World Health Organization classification. MCL mimicking marginal zone lymphoma (MZL) (MCL mimicking MZL) is the rarest variant and could be a potential diagnostic pitfall due to its deceiving "monocytoid" appearance. We report two cases of extranodal MCL mimicking MZL occurring at different sites-the oropharynx and the rectosigmoid colon. Both cases showed unexpected diffuse submucosal lymphoid infiltration of small- to medium-sized lymphocytes with focal monocytoid appearance. Immunohistochemistry showed the presence of an abnormal CD5(-)/CD10(-) B cell population expressing cyclin D1. The diagnosis of MCL was further substantiated by cytogenetic evidence of t(11;14)(q13;q32). Ki-67 proliferation indexes of both cases were low. In summary, MCL mimicking MZL may have unusual morphologic and immunophenotypic characteristics that could be a diagnostic pitfall.
- CD5 negativity
- Mantle cell lymphoma
- Mantle cell lymphoma mimicking marginal zone lymphoma
ASJC Scopus subject areas
- Pathology and Forensic Medicine