Syringoma
Key Points
Syringoma is a benign adnexal tumor derived from the intraepidermal eccrine duct
It can be associated with several systemic syndromes including diabetes mellitus, Down syndrome, Brooke-Spiegler syndrome, and Nicolau-Balus syndrome
Syringoma is classified into four clinical variants: a localized form, a familial form, a milia-like form, and a generalized form
The pathophysiology is largely unknown but has been proposed to be a benign hyperplastic growth that arises from the intraepidermal acrosyringium portion of eccrine ducts in response to an inflammatory reaction or as a hamartoma of pluripotent stem cells
Syringomas typically appear as 1- to 3-mm, soft to firm, skin-colored, yellowish, or translucent papules
Treatment for cosmetic improvement can include laser ablation, electrodesiccation, cryosurgery, trichloroacetic acid, dermabrasion, and chemical peels
Syringomas have been reported to spontaneously regress in rare cases, and improvement following treatment can range from 60% to 100%
Syringoma is a benign adnexal tumor derived from the intraepidermal eccrine duct. It may present as single or multiple papules at puberty or later in life where it affects females more frequently than males, and is seen in about 1% of the population.1,2 Syringoma was first described by Kaposi in 1872,3 and Darier and Jacquet later described the eruptive form as a variant.4
In a large series of 244 cases, Ciarloni et al5 reported a male:female ratio of 1:3.7 and a mean age at presentation of 42 years (range 8-85). Lesions were multiple in 76% of cases, and in 29% the type was eruptive. More than half of these cases involved the face, with 36% occurring on the eyelids. Other sites included the chest (18%) and the neck (17.5%).
Several systemic syndromes have also been associated with syringoma, including diabetes mellitus, Down syndrome, Brooke-Spiegler syndrome, and Nicolau-Balus syndrome. Diabetes mellitus is associated with a clear cell variant of syringoma, consisting of nests of clear cells containing glycogen.6,7 It is thought that elevated glucose accumulates in the skin and within the clear cells.8 In Down syndrome, the incidence of syringomas has been reported in up to 40% of individuals and can be associated with calcinosis cutis.9,10,11 Brooke-Spiegler syndrome is a rare autosomal dominant syndrome with cutaneous manifestations that include syringomas and trichoepitheliomas.12 Nicolau-Balus is a rare autosomal dominant disorder consisting of atrophoderma vermiculata and syringomas.13
In 1987, Friedman and Butler14 proposed a classification of syringoma consisting of four clinical variants: a localized form, a familial form, a generalized form that involved multiple eruptive syringoma lesions, and a milia-like form. Localized syringomas typically occur as isolated or multiple lesions on localized regions of the body and have been reported on the foot, penis, vulva, scalp, face, and eyelids. They usually present as small, firm dermal papules that are flesh colored to red, tan, or brown.
Syringomas can have a rare familial occurrence,15 and a positive family history was reported in 11.5% of 61 patients with syringoma in one study.16 Familial syringomas may be inherited as an autosomal dominant trait or result from either germline or somatic mutations.17,18,19 The most commonly involved site for familial syringomas is the face, particularly the eyelids, followed by the trunk, and less frequently the neck.2,20 An eruptive or generalized presentation is very rare and is most prominent on the trunk.2,21 Milia-like syringoma is a rare variant with a white center similar to milia. Most patients with this variant are Asian with a single lesion.22
The incidence of syringoma in patients with Down syndrome has been reported to be 30 times greater than that in the general population,23 with a prevalence reported to be approximately 18% to 40%.24 While these usually are located in the periorbital region,24 widespread eruptive syringomas associated with Down syndrome are common and have also been reported.25,26 Milia-like syringomas associated with Down syndrome have a higher rate of calcification, which may progress to calcinosis cutis.9,10,11,27,28,29,30 Eruptive syringoma is a rare variant, typically occurring in a generalized form.2,18,31 They usually present at puberty or during childhood in successive crops on the chest, abdomen, neck, arms, eyelids, and upper cheeks. It has been suggested that cases of eruptive syringoma may represent a hyperplastic response to an inflammatory reaction rather than a true adnexal neoplasm.32
The plaque type of syringoma was first described in 1979 by Kikuchi et al33 as another rare distinct variant that is more commonly associated with symptoms, such as pruritus. Cases have been reported on the face, neck, trunk, penis, and acral areas.33,34,35,36,37,38 Plaque-type syringomas are more frequently misdiagnosed as malignant lesions such as morpheaform basal cell carcinoma and microcystic adnexal carcinoma from which they can be differentiated on histopathology.34,35,38
Etiology and Pathogenesis
The pathophysiology of syringomas is largely unknown, but several hypotheses have been proposed for the pathogenesis of the various types.18,21,31 One is that syringomas are benign hyperplastic growths that arise from the intraepidermal acrosyringium portion of eccrine ducts in response to an inflammatory reaction.39,40 Another is that syringomas represent a hamartoma of pluripotent stem cells that precede the pathological process in eruptive syringomas.32,41 An alternate hypothesis suggests that phosphorylase deficiency, resulting from hyperglycemia seen in diabetes, leads to an accumulation of glycogen in the skin and within the clear cells of syringomas.42 Additionally, syringomas may be under hormonal influence. Some vulvar syringomas exhibit estrogen and progesterone receptors demonstrated by immunohistochemical staining.43,44 One report showed that syringomas of the vulva exacerbated during pregnancies with regression in the periods between pregnancies.45
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