INTRODUCTION Sebaceous cell carcinoma is a highly malignant neoplasm that arises from sebaceous glands, and the vast majority of these occur around the eyelids. It can derive from the meibomian glands, glands of Zeis, and from sebaceous glands associated with the pilosebaceous unit. Sebaceous cell carcinoma is an aggressive tumor with a high recurrence rate, a significant metastatic potential, and a notable mortality rate. Although relatively rare, sebaceous gland carcinoma represents the third most common eyelid malignancy, accounting for 1.0% to 5.5% of all eyelid cancers. It affects all races and occurs more commonly in women than in men. It usually presents in the sixth to seventh decades, but cases in younger patients, even children, have been reported. There is a clear link between sebaceous gland carcinoma and prior radiation therapy. It may invade locally into the globe, the orbit, the sinuses, or the brain. Metastases spread via local lymphatics to preauricular and submandibular lymph nodes or by hemotogenous spread to distant sites. Once metastases develop, the five-year survival rate is only 30% to 50%.
CLINICAL PRESENTATION The upper eyelid is the site of origin in about two thirds of all cases, presumably due to a greater number of meibomian glands on the upper eyelid. The clinical appearance is varied and sebaceous cell carcinoma is very frequently misdiagnosed as a benign process. Often it presents as a firm, yellow nodule that resembles a chalazion. It can mimic a chronic blepharo-conjunctivitis or meibomianitis that does not respond to standard therapies (the so-called masquerade syndrome). A more worrisome presentation may be as a plaque-like thickening of the tarsal plate with destruction of meibomian gland orifices and tumor invasion of eyelash follicles leading to madarosis, or loss of lashes. Tumor tends to invade the overlying epithelium which may result in the formation of nests of malignant cells. This is known as pagetoid spread. Pagetoid spread of the tumor may result in diffuse spread of the tumor that replaces the entire thickness of the conjunctiva (intraepithelial carcinoma) and mimics conjunctivitis. This lesion can exhibit multicentric spread to the conjunctiva, corneal epithelium and even to the other eyelid. It may also spread through the caniliculus to the lacrimal excretory system and the nasal cavity.
HISTOPATHOLOGY Sebaceous carcinoma varies from well- to poorly-differentiated tumors, depending on the number of neoplastic cells with sebaceous differentiation. The cells with sebaceous differentiation have abundant, finely vacuolated cytoplasm creating a foamy appearance. The other neoplastic cells have hyperchromatic nuclei, prominent nucleoli, and lightly basophilic cytoplasm. A lobular pattern of tumor is most common in the eyelid, though full-thickness involvement and Pagetoid spread of tumor cells in the conjunctiva or epidermis are also encountered. The tumor cells around the periphery of the lobules often have less cytoplasm and are more basophilic than those toward the center of the lobule. Oil red O stains for lipid within the tumor cells is rarely needed for diagnosis.
DIFFERENTIAL DIAGNOSIS The differential diagnosis includes basal cell carcinoma, squamous cell carcinoma, papilloma, blepharitis, chalazion, ocular cicatricial pemphigoid, cutaneous horns, discoid lupus, pyogenic granulomas, lacrimal sac tumors, and superior limbic keratoconjunctivitis.
TREATMENT Any suspicious eyelid lesion or one that does not respond to medical therapy or recurs in the same location deserves a biopsy. Because eyelid margin sebaceous carcinomas often originate in the deep tarsus, superficial shave biopsies may reveal chronic inflammation but miss the underlying tumor. A full-thickness eyelid biopsy with permanent sections may be required to determine the correct diagnosis. Alternately, a punch biopsy of full-thickness tarsal plate may be diagnostic. Wide surgical excision with microscopic monitoring of the margins is the treatment of choice. Mohs' micrographic surgical excision may be used, but it may not be as successful as in basal cell carcinoma or squamous cell carcinoma due to the possibility of multicentric skip lesions and pagetoid spread. If the tumor is very large or recurrent with spread to the bulbar conjunctiva or to orbital tissues, a subtotal or complete exenteration may be necessary. If evidence of spread to regional lymph nodes is present, the patient will require lymph node or radical neck dissection. Radiation therapy can be considered as an adjunct to local surgery. However, primary treatment with irradiation alone is inadequate, and recurrence usually occurs within three years.
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