ECCRINE SYRINGOMA
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.
