Primary apocrine adenocarcinoma of the lacrimal sac: an extremely rare variant of lacrimal sac neoplasm

A 52-year-old male presented with right eye prominence of 1-year duration. Right eye examination revealed proptosis and limitation of extraocular movements. Magnetic resonance imaging (MRI) of the orbit showed soft tissue mass in the inferomedial orbit with medial rectus involvement and involving lacrimal sac. The patient underwent an incisional biopsy. Histopathology confirmed a diagnosis of primary orbital adenocarcinoma. Positron emission tomography computed tomography (PET CT) did not show the involvement of any other organ. Right orbital exenteration was done for disease control. On histopathology the mass was found to be arising from the lacrimal sac and was reported as apocrine adenocarcinoma. The diagnosis was further confirmed by immunohistochemistry with the tumor staining positive for gross cystic disease fluid protein 15 (GCDFP 15). The patient received adjuvant radiotherapy and is alive without any recurrence at 1 year of follow up. Apocrine adenocarcinomas are rare malignant skin adnexal tumors. Involvement of lacrimal sac is extremely rare with only one case reported in the literature till date. Immunohistochemistry utilizing GCDFP 15 stain can confirm the diagnosis.