Medial rectus muscle myositis as an atypical presentation of mucosa-associated lymphatic tissue lymphoma: A case report

Abstract

Here we describe the rare case of a 55-year-old man with medial rectus muscle myositis as an atypical presentation of non-Hodgkin B-cell mucosa-associated lymphoma (MALT). Pathology and immunohistochemistry of the affected muscle confirmed the diagnosis of a neoplasm. The primary etiology of orbital myositis is Graves' ophthalmopathy, but several other diseases may cause this clinical presentation. Therefore, the neoplastic causes must be eliminated from the differential diagnoses. Non-Hodgkin B-cell mucosa-associated lymphoma is the most common histological type of lymphoma in the orbit, with the conjunctiva and lacrimal glands being the most commonly affected sites. However, it may also present in atypical forms involving others sites and tissues.