Simultaneous presentation of orbital mantle cell lymphoma and endocrine mucin-producing sweat gland carcinoma

Mantle cell lymphoma is a rare malignancy to present in the orbit, comprising only 1-5% adnexal lymphomas. Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is an equally uncommon adnexal tumor of sweat gland origin that may present on the eyelid. Herein we present a case of a 77-year old man with no previous cancer history who presented with painless progressive left globe proptosis and an enlarging left upper lid margin lesion, ultimately determined upon biopsy to be simultaneous orbital mantle cell lymphoma with systemic involvement and isolated eyelid EMPSGC. The pathogenesis, clinical manifestation, and management for each rare disease entity are reviewed and concept of collision tumors is discussed.