Atypical clinical presentation of orbital adenoid cystic carcinoma.

Orbital adenoid cystic carcinoma (ACC) always originates from epithelia of lacrimal gland and typically presents as lacrimal fossa mass. We describe two cases of biopsy-proven orbital ACC without definite lacrimal gland mass. Orbital images showed that the lesions of the two patients were located mainly in retrobulbar space, extending posteriorly to the orbital apex. Both of them had relatively normal lacrimal gland images. Each patient underwent complete ophthalmologic examination and orbital surgery. Histopathological assessment proved to be ACC. Immunohistochemistry showed invasion of the nerve fibers. This report suggests the possibility of orbital ACC without obvious lacrimal gland mass. The two cases of atypical orbital ACC reinforced the differential diagnosis of the diseases.