Coexisting follicular and mantle cell lymphoma with each having an in situ component: A novel, curious, and complex consultation case of coincidental, composite, colonizing lymphoma.

A diagnosis of composite lymphoma is typically prompted by the observation of morphologic discordance. We present a case of a spleen revealing histologic features of follicular lymphoma, without any indication of a second lymphoma. Immunohistochemical stains supported this diagnosis and showed the follicular lymphoma to be BCL2-.