Eccrine Hidrocystoma or Ductal Cyst

Definition: benign cystic lesion of the eyelid characterized by cuboidal epithelium and fluid content.
Incidence/ Prevalence: Although not well studied eccrine hidrocystomas account for less than 5% of all eyelid biopsies.
Etiology: The morphology suggests the cysts are ductal in origin, hence the more common name ductal cyst.
Clinical Findings: The mean age is about 59 years with a range from 39-91 in one series (Singh et al). The patient usually present with a single clear cystic tumor that is close to but not involving the upper eyelid margin. The lesions are usually solitary (71%), and located on the upper eyelid (2/3). Almost all are less than a cm in size and 1/3 are less than 1 mm. About 90% of ductal cysts are close to the eyelid margin but generally don’t involve the margin. Proximity to the lid margin distinguishes the ductal cyst from the apocrine hidrocystoma. The lesion may be pigmented although this occurs in less than 10% of ductal cysts. The lesions may be bilateral although this is also rare.
Gross: The lesion is cystic, contains clear fluid and lined by a smooth surface with occasional infoldings. In the accompanying image one can see a clear cyst (magnified of course) demarcated by the black arrows. There is surrounding fibrous tissue as this lesion was shelled out from the conjunctival surface. Ductal cysts may arise from the conjunctiva as well as from eyelid. The cysts contain clear fluid as opposed to keratinaceous material that is often seen in epidermal or sebaceous types of cysts.
Histopathology: The classic description features a cystic cavity (number 1) with lightly eosinophilic staining material in the center. There is perhaps eosinophilic proteinaceous contents here although it is poorly defined (arrows 5). Eccrine hidrocystoma is lined by a double layer of cuboidal cells (arrows 2 and 3). The inner layer facing the cyst shows some minor budding toward the lumen arrow 2).




















However, often the basal layer is actually flattened evidence that this cyst is of ductal origin. Note in the figure that the surface of the biopsy specimen is keratinized stratified squamous epithelium. This finding may seem trivial but indicates that the location is skin at least slightly away from the eyelid margin; sometimes pathologists are not given that information. Also note just for fun, the pigmentation of the basal layer, extravasated erythrocytes and free pigment in the superficial dermis in combination with a mild perivascular inflammatory infiltrate. Not all eccrine hidrocystomas have a uniform or consistent lining we have seen parts of the cyst lined by stratified squamous epithelium.
Treatment: Complete excision is generally performed without recurrence.
Reference
1. Singh et al. Eye 2005 19;77-9.