Biopsy-proven pigmented poroma with no vascular structure in dermoscopy

Dermoscopic-Histopathological Correlation of Eccrine Poroma: An Observational Study

Background

Eccrine poroma (EP) is a benign adnexal neoplasm that can be pigmented in 17% of cases. Four histopathological variants of EP exist. Dermoscopically, EP can mimic many other skin neoplasms.

Objectives

To provide a dermoscopic-histopathological correlation of EP, classifying the clinical and dermoscopic features of EPs on the basis of their histopathological subtype, in an attempt to better characterize these entities.

Patients and Methods

A single-center retrospective study was conducted. Clinical data were collected; patients were classified on the basis of the 4 histopathological variants of EPs. Dermoscopic images were reviewed. A dermoscopic-histopathological correlation was performed, and the results were compared with literature data.

Results

Twenty-six lesions were included, both pigmented and nonpigmented. Three of the 4 histopathological variants were identified. Different dermoscopic features were observed for each distinct histopathological subtype of EP. The lesions mimicked different types of other skin neoplasms, in particular: nonpigmented hidroacanthoma simplex resembled nonmelanoma skin cancer; pigmented hidroacanthoma simplex appeared like a seborrheic keratosis or a solar lentigo; EPs sensu stricto presented as pink nodules if nonpigmented and were similar to seborrheic keratosis if pigmented; dermal duct tumors appeared as pigmented nodular lesions.

Conclusions

Distinct dermoscopic features appeared to be recurrent in each histopathological variant. Dermoscopy can provide important clues for the diagnosis of EP; the final diagnosis is allowed by histopathology. To achieve a correct diagnosis of EP, because of its clinical and dermoscopic variability, surgical excision is recommended.

Dermoscopy of Adnexal Tumors

Cutaneous adnexal tumors include lesions with apocrine, eccrine, follicular, sebaceous, and mixed differentiation. Most are benign and sporadic, although malignant forms are occasionally observed and some cases develop in the setting of inherited syndromes. These tumors often cause immense diagnostic difficulty. Dermoscopy is a noninvasive technique that has greatly improved the diagnostic accuracy of different skin lesions, including these tumors. We provide a review of the literature on the dermoscopic structures and patterns associated with adnexal tumors. Most patterns associated with this kind of tumor are nonspecific and are observed in other nonadnexal tumors, especially in basal cell carcinomas.

Dermoscopic features and patterns of poromas: a multicentre observational case-control study conducted by the International Dermoscopy Society

BACKGROUND

Poromas are benign cutaneous sweat gland tumours that are challenging to identify. The dermoscopic features of poromas are not well characterized.

OBJECTIVE

To determine the clinical-dermoscopic features of poromas.

METHODS

Cross-sectional, observational study of 113 poromas and 106 matched control lesions from 16 contributors and eight countries. Blinded reviewers evaluated the clinical and dermoscopic features present in each clinical and dermoscopic image.

RESULTS

Poromas were most commonly non-pigmented (85.8%), papules (35.4%) and located on non-acral sites (65.5%). In multivariate analysis, dermoscopic features associated with poroma included white interlacing areas around vessels (OR: 7.9, 95% CI: 1.9-32.5, P = 0.004), yellow structureless areas (OR: 2.5, 95% CI: 1.1-6.0, P = 0.04), milky-red globules (OR: 3.9, 95% CI: 1.4-11.1, P = 0.01) and poorly visualized vessels (OR: 33.3, 95% CI: 1.9-586.5, P = 0.02). The presence of branched vessels with rounded endings was positively associated with poromas but did not reach statistical significance (OR: 2.4, 95% CI: 0.8-6.5, P = 0.10). The presence of any of these five features was associated with a sensitivity and specificity of 62.8% and 82.0%, respectively.

CONCLUSION

We identified dermoscopic features that are specific to the diagnosis of poroma. Overall, however, the prevalence of these features was low. Significant clinical and dermoscopic variability is a hallmark of these uncommon tumours, which are most prevalent on non-acral sites.