Hidrocystomas are benign cystic lesions of sweat glands seen most commonly on the face, especially on the eyelids, in the medial canthus, and less commonly the lateral canthal angle.¹,²,³,⁴,⁵,⁶,⁷ In a large series of more than 5000 benign and malignant noninflammatory lesions excised from the eyelids, 5.9% were hidrocystomas, and these were equally distributed in the upper and lower eyelids.⁴ Other studies reported hidrocystomas to account for 8% to 10.5% of benign eyelid lesions.⁸,⁹

Based on their histologic characteristics and presumed histogenic derivation, hidrocystomas are categorized into apocrine and eccrine types. Apocrine glands are found only at the eyelid margin in association with cilia, and nowhere else in the eyelid skin. Eccrine glands, however, are not present on either the upper or lower eyelid margins or in the perimarginal skin but are sparsely present in the dermis of the pretarsal and preseptal eyelid skin.¹⁰ So eccrine hidrocystomas develop within the eyelid skin away from the eyelid margins and pericilial skin, whereas hidrocystomas on or near the eyelid margins are always apocrine in origin.¹¹,¹²,¹³ De Viragh et al¹² reported that apocrine or eccrine hidrocystomas are often misdiagnosed because the usual histological criteria are masked, probably secondary to intraluminal pressure in the cysts, which flattens their walls and abolishes decapitation secretions.

Apocrine sweat glands are composed of a coiled secretory portion located in the dermis. A short straight excretory duct inserts into the upper infundibular portion of the hair follicle.¹⁴,¹⁵,¹⁶ The apocrine gland secretes an oily fluid with proteins, lipids, and steroids. Secretions appear on the skin surface mixed with sebum since sebaceous glands open into the same hair follicle.¹⁷ Apocrine glands secrete in periodic spurts and release their products by “decapitation,” where membrane-bound cytoplasm from the apical surface of the secretory cells bud off into the lumen of the duct.

Apocrine hidrocystomas were first described by Mehregan in 1964¹⁸ and are thought to derive from the secretory portion of the apocrine gland. They are usually solitary lesions, but can also be multiple,¹⁹ and vary in size from 3 mm to about 15 mm.²⁰ Multiple apocrine hidrocystomas have been described in two rare ectodermal dysplasias. Goltz-Gorlin syndrome (focal dermal hypoplasia syndrome) is a sporadic or X-linked dominant disease most common in females and characterized by atrophic hyperpigmented and hypopigmented macules, linear skin atrophy, microcephaly, microphthalmia, midface hypoplasia, malformation of the ears, apocrine hidrocystoma of the eyelids, syndactyly, and mental retardation.²¹,²² Schopf-Schulz-Passarge syndrome is an autosomal recessive condition characterized by hypotrichosis, hypodontia, palmar and plantar hyperkeratosis, nail fragility, hypotrichosis, and multiple eyelid apocrine hidrocystomas.²³,²⁴

Eccrine glands are composed of an intraepidermal spiral duct, a dermal duct consisting of a straight and coiled portion, and a coiled secretory tubule deep in the dermis.¹⁷ The eccrine gland opens directly onto the skin surface through a sweat pore. These glands produce a clear odorless secretion, consisting primarily of water.

Eccrine hidrocystomas were first reported by Robinson in 1893²⁵ in workers laboring in humid and warm environments. The cysts tend to enlarge with exercise and in warm environments, due to increased sweat retention.²⁶ Eccrine hidrocystomas are most prevalent in adults between 30 and 70 years and present as small, tense, thin-walled cysts 1 to 6 mm in diameter and can occur as single or multiple lesions.²,²⁰ They are very rare in children, and when present can be associated with ptosis and astigmatism.²⁷,²⁸ Solitary eccrine hidrocystomas occur equally among males and females, but multiple cysts are mainly seen in females.²⁹

Graves disease has been associated with multiple eccrine hidrocystomas.³⁰ It is suggested that these are due to hyperhidrosis, which can be seen in hyperthyroid patients, and the cysts tend to disappear after treatment of the hyperthyroidism.³⁰