Eccrine syringomas are extremely common benign skin growths. They are most often found on the lower eyelids and malar cheek regions of adults. These small tumors are of no clinical significance and are routinely ignored in clinical practice.
Clinical Findings: Eccrine syringomas are some of the most common benign skin tumors to affect human- kind. They are believed to be more common in women than in men. They typically manifest in adulthood as flesh-colored, small (2-4 mm) papules on the lower eyelids or upper cheek regions. They are usually multiple and symmetric. Some have a slight yellow or tan hue. Other areas of the body on which syringomas are seen include the upper eyelids, neck, and chest. They have been reported to occur on any region of the body. Plaque-like syringomas have been reported to occur on the forehead, and they have the appearance of a flesh-colored to slightly yellow, broad, flat plaque with minimal to no surface change. They can be quite large, up to 4 to 5 cm in diameter. They are essentially asymptomatic, but occasionally a patient complains of slight intermittent itching or of an increase in size with strenuous physical activity. This is possibly explained by the eccrine nature of the tumors: Under conditions of activity, an increase in sweating causes the tumors to transiently appear to enlarge. There are specific variants seen in patients with diabetes mellitus and in those with Down syndrome. A form of eruptive syringoma has been described that typically afflicts the anterior trunk and the penile shaft. Linear syringomas have been reported to occur on a unilateral limb, and these have been termed unilateral linear nevoidal syringomas.
The clinical differential diagnosis of eccrine syringomas is relatively limited when the clinician encounters symmetric small papules on the lower eyelids. The differential diagnosis for a solitary syringoma is broad and includes other adnexal tumors as well as basal cell carcinoma. The most difficulty arises when reviewing the histological features of a syringoma that has been biopsied in a superficial manner. If the pathologist is not given a thick enough specimen, the eccrine syringoma can mimic a microcystic adnexal carcinoma. These two tumors, one benign and the other malignant, can have very similar histological features in the superficial dermis. In some cases, it is only with a full-thickness biopsy that a pathologist can confidently differentiate the two tumors.
Histology: The overlying epidermis is normal. The tumor is based within the dermis and is sharply circumscribed. The syringoma typically does not penetrate deeper than the upper third of the dermis. Clusters of cells with a pale cytoplasm are found throughout the tumor. A background of sclerotic stromal tissue is always appreciated. A characteristic finding is the “tadpole” sign. The tadpoleor comma-shaped, dilated ductal eccrine gland apparatus is pathognomonic for eccrine syringoma. Clear cell variants are associated with diabetes mellitus. A microcystic adnexal carcinoma is poorly circumscribed, is asymmetric, and infiltrates into the underlying subcutis.
Pathogenesis: Eccrine syringomas are believed to be an overgrowth of the eccrine sweat ductal apparatus. Researchers have proposed that this proliferation is caused by an inflammatory response to an as yet undetermined antigen. The precise pathogenesis of eccrine syringomas is unclear. Familial patterns suggest a genetic predisposition, but most patients do not have a family history to support genetic transmission.
Treatment: No treatment is necessary. If one wishes to pursue therapy, it should be done with caution, because treatment experiences are anecdotal, and scarring may have a worse appearance than the syringoma itself. Electrocautery, light cryotherapy, chemical peels, laser resurfacing, dermabrasion, and excision have been reported with variable results.