Skin nonmelanocytic tumor
Adnexal tumors
Sweat gland derived (apocrine & eccrine glands)
Syringoma
Authors: Aadil Ahmed, M.D., Sara C. Shalin, M.D., Ph.D.
Resident / Fellow Advisory Board: Caroline I.M. Underwood, M.D.
Minor changes: 16 March 2021
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Syringoma skin[title] pathology
Table of Contents
Definition / general | Essential features | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Ahmed A, Shalin SC. Syringoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticsyringoma.html. Accessed June 23rd, 2021.
Definition / general
- Benign adnexal neoplasm of sweat gland (eccrine) origin
- Most common clinical presentation on lower eyelids of women
- Appears to derive from sweat duct ridge
- Malignant counterpart can be termed syringomatous carcinoma / sweat gland carcinoma
Essential features
- Often multiple 1 - 4 mm, firm papules
- Well circumscribed dermal lesion with comma shaped ductules lined by basaloid cells and with sclerotic stroma
ICD coding
- ICD-10: D23.9 - other benign neoplasm of skin, unspecified
Epidemiology
- F > M for all syringomas (J Am Acad Dermatol 2016;74:1234)
- Typically occurs after puberty; most common during reproductive years (may be due to hormonal influence)
- More common in people of Asian decent
- Increased incidence in Down, Nicolau-Balus and Brook-Spiegler syndromes
- Possible familial association (up to 20%)
Sites
- Dependent on clinical variant (for example, localized versus eruptive) (J Am Acad Dermatol 2016;74:1234)
- Localized variant: periorbital > vulvar / penile > scalp > axillary > facial > forearm / hand (J Am Acad Dermatol 2016;74:1234)
- Eruptive variant: anterior trunk > neck > axillae (Indian J Dermatol 2013;58:326)
- Most common site < 15 years old: neck and anterior trunk (Indian J Dermatol 2013;58:326)
Pathophysiology
- Represents adenoma of acrosyringium, the intraepidermal eccrine sweat duct (Arch Dermatol 1967;96:500)
Etiology
- Uncertain, possible hormonal influence
- Clear cell variant has an association with diabetes (Am J Dermatopathol 1984;6:131)
Clinical features
- Generally asymptomatic
- Vulvar syringomas often present with pruritus and are often bilateral (J Am Acad Dermatol 2003;48:735)
- Oral contraceptive pills or menstruation may worsen symptoms or increase lesion size
- Symptoms may worsen in summer
- Clinical variants
- Localized
- Generalized
- Multifocal
- Eruptive
- Down syndrome
- Familial
Diagnosis
- On face, in particular, can be clinically suspected
- Biopsy required for confirmation
Prognostic factors
- Benign, nonprogressive lesions but can be cosmetically bothersome if multiple
- Recurrence, scarring and dyspigmentation after treatment
Case reports
- 18 year old woman with disseminated syringomas on forearm / hands (Cureus 2018;10:e3619)
- Woman in her 30s presenting with disseminated asymptomatic papules diagnosed as eruptive syringomas (JAMA Dermatol 2018;154:835)
- 40 year old woman with vulvar nonclear cell syringoma associated with pruritus and diabetes mellitus (Case Rep Dermatol Med 2013;2013:418794)
- 68 year old woman with plaque type syringoma associated with pruritus and masquerading as microcystic adnexal carcinoma (Am J Dermatopathol 2019;41:e98)
Treatment
- Treatment necessary only for cosmetic reasons or quality of life
- Excision or cryotherapy / laser therapy is most common
- Does not respond to topical steroids
- Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Clinical images
Gross description
- 1 - 4 mm, firm, skin colored papule with or without eruption
Gross images
- See clinical images
Microscopic (histologic) description
- Well circumscribed proliferation with 2 components:
- Epithelial cells forming ductules, nests, cysts and cords
- Cells are basaloid, cuboidal and double layered (in ductules) with an eosinophilic cuticle
- Ducts: often round, comma or tadpole shaped (paisley pattern)
- May have cytoplasmic clearing due to glycogen accumulation (clear cell syringoma), more common in diabetics
- Some small cysts may have squamous lining
- Variable luminal proteinaceous debris / keratin debris
- Stromal fibrosis / sclerosis
- Epithelial cells forming ductules, nests, cysts and cords
- Usually in superficial reticular dermis, rarely deep dermal extension
- No cytologic atypia
- Very rare mitoses
- Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Microscopic (histologic) images
Contributed by Aadil Ahmed, M.D. and Sara C. Shalin, M.D., Ph.D.
Well circumscribed syringoma
Comma shaped ductules and nests
Basaloid proliferation
Paisley or tadpole shaped pattern
Clear cell change
Clear cell syringoma
Conventional and clear cell components
Incidental syringoma
Cytology description
- Basaloid cells, possibly in clusters
- May be clear cells in clear cell variant
- No cytologic atypia
- Very rare mitoses
- Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Positive stains
- Immunohistochemistry generally not required for diagnosis
- CK AE1 / AE3
- CEA: luminal surface of sweat ductal cells
- CK5, EMA: solid strands and outer cells of ductules
- Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Negative stains
- Estrogen receptor / ER and progesterone receptor / PR; however, some studies show PR > ER positivity (J Cutan Pathol 1995;22:442)
- SOX10 (Appl Immunohistochem Mol Morphol 2019;27:114)
Electron microscopy description
- Eccrine origin
Molecular / cytogenetics description
- Multiple syringomas may be inherited in autosomal dominant fashion; linked to chromosome 16q22 (Br J Dermatol 2010;162:1083)
Sample pathology report
- Skin, eyelid, biopsy:
- Syringoma
- Microscopic description: Histologic sections show skin with an unremarkable epidermis. Within the superficial dermis, a circumscribed proliferation of multiple ductular structures lined by 2 layers of epithelial cells is present coursing within densely fibrotic stroma. There is minimal cytologic atypia and mitoses are not abundant.
Differential diagnosis
- Desmoplastic trichoepithelioma:
- Practically nonexistent in vulva, usually single lesion with keratinous cysts next to strands of basaloid cells and no eosinophilic cuticle
- Presence of papillary mesenchymal bodies (if present) and entrapped CK20 positive Merkel cells
- Microcystic adnexal carcinoma:
- Practically nonexistent in vulva, poorly circumscribed, deeply infiltrative, with frequent perineural invasion
- Morpheaform basal cell carcinoma:
- Histologically similar with strand-like growth pattern
- Sclerotic stroma with deeply infiltrative, basaloid cells (Arch Pathol Lab Med 2017;141:1490)
Board review style question #1
Which of these characteristics is typical of this well circumscribed, dermal lesion?
- Associated with Turner syndrome
- May recur after excision
- Often multiple 1 - 4 mm, firm, flesh colored papules
- Painful lesions
- Strongly SOX10 immunoreactive
Board review style answer #1
C. Often multiple 1 - 4 mm, firm, flesh colored papules. The image shows a syringoma. These lesions are often multiple 1 - 4 mm, firm, flesh colored papules. They are typically asymptomatic but may present with pruritus. Various cell components are immunoreactive for CEA, EMA and CK5 but not for SOX10. They have benign behavior and excision is adequate. They are associated with Ehlers-Danlos, Marfan and Down syndromes.
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Board review style question #2
Clear cell change seen in syringomas is due to
- Clearing artifact
- Globulin
- Glycogen
- Lipids
- Mucin
Board review style answer #2
C. Glycogen. The ductal cells in syringoma can infrequently exhibit clear cell change in focal areas that is due to accumulation of glycogen. Rarely, all cells are glycogen rich, termed clear cell variant and commonly associated with diabetes mellitus.
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