A 27-year-old woman with no remarkable medical history presented with an asymptomatic tumor of several years’ duration on the scalp. Physical examination revealed a firm, skin-colored, pedunculated lesion with a diameter of approximately 2 cm.

Evaluation of the lesion with polarized light dermoscopy showed a polymorphous vascular pattern with hairpin, dotted, glomerular, and arborizing vessels with elliptical endings, white areas around the vessels, and blue-gray peripheral pigmentation. The histopathologic features were consistent with pigmented eccrine poroma (Figs. 1, 2).

Figure 1.

Photograph of lesion on the frontoparietal area of the scalp.

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Figure 2.

Dermoscopic appearance of the lesion (polarized light dermoscopy).

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Eccrine poroma is a benign adnexal tumor derived from acrosyringeal cells. Onset is most common between the fourth and sixth decades of life and the tumor shows no predilection for sex.1–3 It usually occurs on the hands and feet, but has been reported in other areas, although scalp lesions are rare.4,5 Clinically, it presents as a firm nodule, papule, or plaque.1,5,6 Pigmented and nonpigmented variants exist, although the latter are less common.1,3,5

Eccrine poroma exhibits a wide variety of dermoscopic patterns frequently suggestive of other common skin tumors.4,5 One of these patterns is the polymorphous vascular pattern, which consists of different types of vessels, including cherry blossom vessels. These are arborizing vessels with elliptical or semi-elliptical endings and they were a key diagnostic finding in our patient.3–5 Other characteristic dermoscopic findings are structureless yellowish areas, milky red globules, interlacing white areas around vessels, and blue-gray globules in pigmented lesions.3–5

Histologic findings include nests or cords of basaloid cells connected to the epidermis1,4,6 as well as differentiation towards poroid cells, characterized by the formation of small ductal lumina.1,4,6 Melanocytes and melanin are observed in pigmented variants.2,4

The differential diagnosis includes benign lesions such as pyogenic granuloma, seborrheic keratosis, and angiofibromas, and malignant lesions, such as squamous cell carcinoma, basal cell carcinoma, and melanoma.1,5,6 Although the definitive diagnosis of eccrine poroma is histopathologic, dermoscopic features, while not pathognomonic, can help establish a tentative diagnosis.1,3,5

Although eccrine poroma is benign, the treatment of choice is surgery, as there have been reports of transformation to eccrine porocarcinoma.2

The authors declare that they have no conflicts of interest.