Adenocarcinoma in situ (ductal type) ex pleomorphic adenoma of the lacrimal gland

PURPOSE: To present the clinical and histopathological characteristics of a rare case of ductal carcinoma in situ ex pleomorphic adenoma in the lacrimal gland. OBSERVATIONS: A 73-years-old Caucasian female presented with complaints of double vision and pain in the left eye region. Clinical examination revealed ptosis and exophthalmos of the left eye as well as diplopia on downward gaze. Magnetic resonance imaging of the left orbit demonstrated a 17 × 22 mm homogeneous tumor in the left lacrimal fossa. The tumor was excised in toto. Histopathological examination revealed a pleomorphic adenoma with ductal structures with benign looking epithelial cells, surrounded by myoepithelial cells. Tumor areas with cribriform architecture consisting of ductal structures with abnormal luminal epithelial cells and intact myoepithelial cell layer were also present. The surgical margins were clear. All luminal and myoepithelial cells were positive for cytokeratin 7, the luminal cells in the cribriform areas were positive for human epidermal growth factor 2 and androgen receptor. The myoepithelial cells were positive for cytokeratin 5, calponin and focally for glial fibrillar acid protein. The findings were diagnostic for ductal carcinoma in situ ex pleomorphic adenoma. Next generation sequencing Oncomine Comprehensive Assay mutation analysis found mutations in the BRCA2 (p.K3326*), BAP1 (p.S395*), and TP53 (p.E285K) genes in the ductal carcinoma in situ and BRCA2 (p.C9976A) in the pleomorphic adenoma part. CONCLUSION AND IMPORTANCE: To our knowledge, this tumor is only the second described ductal carcinoma in situ ex pleomorphic adenoma of the lacrimal gland.