Primary lacrimal sac tumor is extremely rare, and moreover, glandular tumor is exceptional. Herein, we described the first documented case of primary ductal adenocarcinoma of the lacrimal sac. A 79-year-old Japanese female presented with persistent swelling of her left lower eyelid. Computed tomography demonstrated an irregular-shaped tumor involving the left lacrimal sac, lower eyelid, sinonasal tract, and internal side of the left orbit. Biopsy from the eyelid revealed a poorly differentiated adenocarcinoma. Histopathological study of the resected lacrimal sac tumor revealed an infiltrative neoplastic growth that was composed of cribriform structures with comedonecrosis. The neoplastic cells had relatively rich granular eosinophilic cytoplasm and large round to oval nuclei containing conspicuous nucleoli. The left cervical lymph nodes had metastatic carcinoma. Immunohistochemically, the neoplastic cells were diffusely positive for gross cystic disease fluid protein-15 and androgen receptor. Moreover, mammalian target of rapamycin (mTOR), 4E-BP1, and p4E-BP1 were expressed. According to these results, an ultimate diagnosis of primary ductal adenocarcinoma of the lacrimal sac was made. Only 9 cases of primary lacrimal sac adenocarcinoma have been reported, and this is the first reported case of ductal adenocarcinoma of the lacrimal sac. Ductal adenocarcinoma of the salivary gland shows an aggressive clinical course, and the present case had multiple cervical lymph node metastases. This report is the first to demonstrate that mTOR pathway proteins, which are central proteins involved in carcinogenesis, are activated in ductal adenocarcinoma. Therefore, mTOR inhibitor may be a potential candidate for treatment of this highly aggressive carcinoma.
Keywords: Ductal adenocarcinoma; lacrimal sac; mTOR pathway.