Sebaceous adenoma (SA) was first reported in 1949 by Van Walbeek¹ and was characterized as a benign tumor that presents clinically as a tan, pink, or yellow nodule or papule. It is a very rare benign tumor that is a common finding in Muir-Torre syndrome (MTS), so much so that it has been regarded as pathognomonic for that disorder.² However, isolated nonsyndromic cases have also been described.³

MTS is a rare cancer predisposition syndrome characterized by unusual cutaneous tumors and internal systemic malignancies.⁴,⁵ The cutaneous tumors associated with MTS are primarily SA and sebaceous carcinoma, keratoacanthoma, and basal cell carcinoma.⁴,⁵,⁶ Colorectal adenocarcinoma and genitourinary carcinoma are the most common types of internal malignancies, occurring in 40% and 25% of cases, respectively.⁶,⁷

On the eyelids, SA is exceedingly rare. Jagan et al⁸ identified only 9 cases of SA (0.15%) among 5884 eyelid lesions. Nevertheless, the diagnosis of a solitary SA should raise a strong suspicion of MTS, and these patients, as well as their first-degree relatives, should undergo a systemic evaluation to exclude gastrointestinal and genitourinary malignancy.⁶ These systemic malignancies may occur many years after the onset of SA so that long-term surveillance is necessary. It is therefore important to counsel all patients with an SA that there is a small increased risk of internal malignancies long after the initial diagnosis of SA.⁶,⁹

Sebaceous glands are found abundantly in the eyelids as glands of Zeiss and meibomian glands, and SA on the eyelids can arise from these structures. The tumors are usually small in size, measuring 5 mm or less,¹⁰,¹¹ although rarely they can attain a much larger size of up to 2 cm associated with rapid growth.¹² SA lesions can also rarely develop in the caruncle, which contains both conjunctival and cutaneous dermal elements.¹³,¹⁴,¹⁵ Less commonly they have been reported in the bulbar conjunctiva,¹⁶,¹⁷,¹⁸,¹⁹,²⁰ even though sebaceous glands are normally not present in the conjunctiva.¹³,¹⁴,¹⁷,²¹ It is unclear how a tumor of sebaceous origin can arise in the bulbar conjunctiva, but it has been suggested that this might occur from faulty migration of sebaceous gland cells from the caruncle through the nasal bulbar conjunctiva or derived from pluripotent basal cells of the conjunctival epithelium.¹⁸ One case of an SA of the cornea has been reported. The mechanism of its development is unknown, but it was suggested to derive from pluripotential limbal epithelial stem cells that differentiated into sebaceous cells, then developed into an SA with intraepithelial growth into the cornea.²² Alternatively, previous trauma could have initiated the development of the SA from conjunctivalization of the cornea.

Fewer than 20 cases of SA involving the eyelid or conjunctiva have been reported.³,⁹,¹²,¹⁷,²³,²⁴,²⁵

The mean patient age at diagnosis of the eyelid lesion was 54.4 years (range 23-83 years), and most patients were male (93%). The upper eyelid was predominantly involved, with rare involvement of the medial canthus.¹²,²⁴,²⁶,²⁷