|Description||Poromas are uncommon, benign sweat gland tumors that are clinically and dermoscopically challenging to diagnose. Dermoscopic features associated with poroma include branched vessels with rounded endings, white interlacing areas around vessels, yellow structureless areas, and milky-red globules.|
|Author(s)||Ofer Reiter · Mike Marchetti · Cristina Carrera|
|Responsible author||Ofer Reiter → send e-mail|
|Status update||September 5, 2018|
|Status by||Ralph P. Braun|
Poromas are uncommon, benign sweat gland tumors that are clinically and dermoscopically challenging to diagnose. Dermoscopic features associated with poroma include branched vessels with rounded endings, white interlacing areas around vessels, yellow structureless areas, and milky-red globules.
Poromas are uncommon benign tumors that are derived from the ducts of eccrine or apocrine sweat glands. They are often located on the volar surfaces of the hands or feet but can be found on any location of the body. Poromas usually present as a red to pink papule, nodule, or plaque. Other clinical features include an indented moat with collarette scale surrounding the lesion and a tendency to bleed with minor trauma  .
In a study conducted by the International Dermoscopy Society , 113 poromas from sixteen contributors were examined dermoscopically and compared to 106 clinically matched control lesions. The features found to be most useful for the diagnosis of poroma included branched vessels with rounded endings (30.1%), white interlacing areas around vessels (23%), yellow structureless areas (31.9%), and milky-red globules (19.5%). Additional findings that were common but not specific for poromas included: polymorphous vessels (36.3%), blood spots (37.2%), erosions/ulcers (25.7%), and milky-red areas (17.7%).
Branched vessels with rounded endings:
White interlacing areas around vessels:
Yellow structureless areas:
Four dermoscopic patterns were described for poromas:
Pattern 1 - Appears most commonly on hands and feet and includes branched vessels with rounded endings, collarette of scale, blood spots, yellow structureless areas, milky-red globules and milky-red areas.
Pattern 2 – Appears on the trunk or non-acral extremities and includes polymorphous vessels, white interlacing areas around vessels, and branched vessels with rounded endings.
Pattern 3 – Appears anywhere on the skin surface as a relatively small papule and is either without vessels or with branched vessels with rounded endings. Clinically, these lesions simulated nodular basal cell carcinoma but dermoscopically they did not have BCC-specific features.
Pattern 4 - Appears anywhere on the skin surface as a relatively large keratotic plaque that is pigmented in up to a third of cases. It frequently exhibited blood spots, keratin/scale, and atypical hairpin vessels.
In the aforementioned study, numerous clinical and/or dermoscopic differential diagnoses were considered for poromas, including: melanoma, squamous cell carcinoma, basal cell carcinoma, seborrheic keratosis, nevus, skin metastasis, pyogenic granuloma, verruca, collision tumor, dermatofibroma, among others. Others have similarly reported that the dermoscopic features of poromas can mimic those found in pyogenic granuloma, angioma, seborrheic keratosis, dermatofibroma, nevus, squamous cell carcinoma, basal cell carcinoma, and melanoma     .
- Marchetti et al.: Dermoscopic features and patterns of poromas: a multicentre observational case-control study conducted by the International Dermoscopy Society. J Eur Acad Dermatol Venereol 2017;. PMID: 29194789. DOI.
- Ferrari et al.: Eccrine poroma: a clinical-dermoscopic study of seven cases. Acta Derm. Venereol. 2009;89:160-4. PMID: 19326001. DOI.
- Lallas et al.: Eccrine poroma: the great dermoscopic imitator. J Eur Acad Dermatol Venereol 2016;30:e61-e63. PMID: 26333195. DOI.
- Bombonato et al.: Pigmented eccrine poroma: dermoscopic and confocal features. Dermatol Pract Concept 2016;6:59-62. PMID: 27648386. DOI.
- Espinosa et al.: Dermoscopy of non-pigmented eccrine poromas: study of Mexican cases. Dermatol Pract Concept 2013;3:25-8. PMID: 23785633. DOI.
- Minagawa & Koga: Dermoscopy of pigmented poromas. Dermatology (Basel) 2010;221:78-83. PMID: 20516657. DOI.