Plasmacytomas are plasma cell neoplasms that rarely involve ocular adnexal tissues as a primary lesion or secondary manifestation of plasma cell myeloma. Only one case of plasmacytoma involving the lacrimal drainage system, to our knowledge, is described in the literature. The clinical presentation of ocular adnexal primary plasmacytoma typically relates to its mass effect. In this clinicopathologic report, we describe an unusual presentation of primary plasmacytoma of the lacrimal canaliculus as infectious canaliculitis.