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U tuyến Pleomorphic chiếm khoảng 5% của tất cả các khối u quỹ đạo, 25% khối lượng hố lệ đạo và 50% của tất cả các khối u biểu mô của tuyến lệ đạo. Hầu hết các ảnh hưởng đến các thùy quỹ đạo và trở nên rõ ràng trong thập kỷ thứ tư và thứ năm là một khởi đầu chậm chạp của proptosis không đau | PLASTIC and ORBITAL SURGERY Very rarely the affected ductule will become infected with Actinomyces this causing a slightly inflamed and chronically discharging eye. Pleomorphic adenoma Pleomorphic adenomas account for about 5 of all orbital tumours 25 of lacrimal fossa masses and 50 of all epithelial tumours of the lacrimal gland. Most affect the orbital lobe and become evident in the fourth and fifth decade as a slow onset of painless proptosis and infero-medial displacement of the globe the much rarer palpebral lobe lesions present in young people with a shorter history of a hard mobile mass above the lateral part of the upper tarsus. Orbital lobe tumours show a smooth expansion of the lacrimal gland fossa by an oval lesion in which calcification is rare the mass causing displacement of orbital structures and often flattening of the globe Figure 12.10 it is unusual for these tumours even when large to extend anterior to the orbital rim. In contrast the rare palpebral lobe tumours show a normal gland with an enlarged rounded anterior surface extending outside the orbital rim on CT scan. The key to treatment of pleomorphic adenomas is recognition on the basis of Figure 12.10 CT scan of a typical pleomorphic adenoma showing displacement and flattening of the globe by a round lesion that may cause scalloping of the bone in the lacrimal fossa. clinical history and radiological signs with avoidance of biopsy. Because of the long-term risk of spontaneous malignant transformation tumours of the orbital lobe should be excised intact through a lateral orbitotomy and breach of the pseudocapsule of compressed tissues avoided to this end the tumour is handled at all times with a malleable retractor and not with any form of forceps. Palpebral lobe pleomorphic adenomas sometimes mistaken for large chalazia and curetted are excised intact through an upper eyelid skin-crease incision. Breach of the pseudocapsule of these tumours risks a pervasive recurrence of tumour sometimes .
