There are a number of cutaneous cystic lesions that can simulate neoplasms. In this section we discuss some of the more important ones that can affect the eyelids, beginning with eccrine hidrocystoma (1,2,3,4,5,6,7,8).

Eccrine hidrocystoma is a ductal retention cyst of an eccrine sweat gland (1). It appears to be more common in the eyelid region than elsewhere in the body (2). It usually occurs on the cheeks and eyelids of adult women and may be similar clinically to other cutaneous cysts. In contrast to apocrine hidrocystoma, which is almost always solitary, eccrine hidrocystoma is more likely to be multiple. Eccrine hidrocystomas develop from retention of sweat. Heat, humidity, and perspiration can cause them to become larger, more numerous, and more symptomatic (3). Hence, they tend to increase in number and size in summer and decrease in winter.

Clinically, eccrine hidrocystoma characteristically appears as a clear cystic translucent lesion, usually near the eyelid margin. The overlying skin is usually smooth and shiny (1,2,3,4,5). It may be indistinguishable clinically from apocrine hydrocystoma. It can occasionally have a bluish color, a finding that is more common with apocrine hidrocystoma (to be discussed). Ultrasound biomicroscopy has been used to detect the cystic nature of the lesion and to differentiate it from melanoma and other solid tumors (8).

Histopathologically, eccrine hidrocystoma is a clear cystic lesion lined by 2 layers of cuboidal epithelial cells. There is no evidence of apocrine decapitation secretion as seen with apocrine hidrocystoma. No myoepithelial cells are observed (1,2,3,4,5,6,7).

Management includes observation or local excision. The cystic structure collapses if traumatized or surgically incised.

Apocrine hidrocystoma (apocrine cystadenoma; sudoriferous cyst) is a retention cyst of an apocrine gland (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16). It can develop from the apocrine glands of the eyelids (glands of Moll), in which case it usually occurs near the eyelid margin, corresponding to the orifices of Moll’s glands. It is more common near the medial canthus. There is no gender predisposition. It generally occurs in adults, with a mean age of 55 years, but is occasionally seen in children (2,5,6).

Apocrine hidrocystoma is a smooth or multiloculated cystic lesion that can develop on the eyelid, eyebrow, or near the medial or lateral canthus (1,2,3,4,5,6,7). It frequently has a bluish color and may resemble a blue nevus or melanoma. It can range from 1 mm to more than 1 cm in diameter.

Microscopically, apocrine hidrocystoma is a cystic lesion with a clear lumen lined by a double layer of cells (1,2,3,4,5,6,7). The innermost layer has apical snouts that project into the lumen, a characteristic feature of apocrine cells. The outermost layer consists of flattened myoepithelial cells. The cells also contain PAS-positive, diastase-resistant granules on their apical surfaces. Some authorities regard apocrine hidrocystoma as a form of papillary cystadenoma rather than a retention cyst, because the secretory cells do not appear flattened, as seen with a true retention cyst (1,4).