What type of cyst is associated with lesions on the external angle of the eye, including hair follicles?

A dermoid cyst is correctly identified as the type of cyst associated with lesions at the external angle of the eye, particularly those that may involve hair follicles. Dermoid cysts are benign tumors that typically contain skin components such as hair, sebaceous glands, and sweat glands, and they often present as well-defined lumps near the eye. These cysts can occur along the embryonic fusion lines where ectoderm and mesoderm meet, which explains their location in areas like the outer canthus of the eye.

In contrast, a chalazion is a cyst that arises from a blocked meibomian gland, typically presenting as a localized swelling on the eyelid rather than at the angle of the eye and does not involve hair follicles. A pterygium is a growth of fleshy tissue on the conjunctiva that can extend onto the cornea but is not cystic and does not contain hair follicles. A conjunctival cyst represents a fluid-filled sac on the conjunctiva but is also distinct in appearance and structure from a dermoid cyst and is not commonly associated with hair follicles. Thus, the characteristics of a dermoid cyst make it the only appropriate choice for this question.