Photo Quiz

Rapidly Growing Red Nodule on the Scalp


Am Fam Physician. 2021 Jun 15;103(12):755-756.

A 79-year-old patient presented with a lesion on the scalp, which they noticed one month earlier because of a short episode of bleeding. The lesion was asymptomatic but enlarged rapidly. There was no improvement with topical antibiotics. The patient had a history of coronary artery disease and hypertension but no history of malignancy.

Physical examination revealed a 2-cm, fleshy, erythematous, round, exophytic nodule over the frontal scalp (Figure 1).




Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?

  • A. Amelanotic melanoma.

  • B. Angiosarcoma.

  • C. Cutaneous metastasis.

  • D. Keratoacanthoma.

  • E. Porocarcinoma.


Answer is E: porocarcinoma. Eccrine porocarcinoma is a rare eccrine gland tumor that accounts for 0.005% to 0.01% of all cutaneous tumors.1 The disease is most prevalent in adults 50 to 80 years of age.1 The pathogenesis of porocarcinoma is not fully understood. The lesion may develop from eccrine poromas (porocarcinoma's benign counterpart) through various triggers, including chronic actinic damage.2

Clinically, a porocarcinoma typically presents as an asymptomatic erythematous nodule. 3 The lesion most commonly appears on the lower extremities but may occur anywhere on the body, including the scalp.1 Porocarcinomas may be aggressive with distant metastasis. A history of bleeding, rapid growth, pain, or pruritus may indicate a more aggressive clinical course.3 Histologically, eccrine porocarcinomas typically appear as broadly anastomosing bands of epithelial downgrowths composed of small pleomorphic atypical epithelioid cells, conspicuous mitotic activity, ductal differentiation, and increased dilated blood vessels in the dermis.1,2

Although no standard of care has been established, a recent systematic review recommends imaging to rule out metastasis in patients with porocarcinomas on the extremities, buttocks, or genitalia and in those with worrying clinical features.1 A wide local excision with 2- to 3-cm margins is first-line therapy for eccrine porocarcinomas.1 Mohs micrographic surgery has also been shown to be an appropriate treatment and may have a lower local recurrence rate and reduced rates of metastasis than wide local excision.1

Amelanotic, or hypomelanotic, melanoma may be difficult to diagnose because the lack of pigment inhibits use of color criteria in its detection.4 This uncommon form of melanoma has been described in all histologic melanoma subtypes and typically presents as a rapidly growing, skin-colored to red papule or nodule on chronically sun-exposed skin in older patients. It may bleed or ulcerate. Amelanotic melanoma has a poorer prognosis than pigmented forms, possibly because of diagnostic delay.

Angiosarcomas are rare aggressive soft tissue vascular neoplasms that commonly present as rapidly growing bruises, blue-black n

Address correspondence to Ossama Abbas, MD, at Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


show all references

1. Nazemi A, Higgins S, Swift R, et al. Eccrine porocarcinoma: new insights and a systematic review of the literature. Dermatol Surg. 2018;44(10):1247–1261....

2. Belin E, Ezzedine K, Stanislas S, et al. Factors in the surgical management of primary eccrine porocarcinoma: prognostic histological factors can guide the surgical procedure. Br J Dermatol. 2011;165(5):985–989.

3. Riera-Leal L, Guevara-Gutiérrez E, Barrientos-García JG, et al. Eccrine porocarcinoma: epidemiologic and histopathologic characteristics. Int J Dermatol. 2015;54(5):580–586.

4. Wee E, Wolfe R, Mclean C, et al. Clinically amelanotic or hypomelanotic melanoma: anatomic distribution, risk factors, and survival. J Am Acad Dermatol. 2018;79(4):645–651.e4.

5. Young RJ, Brown NJ, Reed MW, et al. Angiosarcoma. Lancet Oncol. 2010;11(10):983–991.

6. El Khoury J, Khalifeh I, Kibbi AG, et al. Cutaneous metastasis: clinicopathological study of 72 patients from a tertiary care center in Lebanon. Int J Dermatol. 2014;53(2):147–158.

7. Kwiek B, Schwartz RA. Keratoacanthoma (KA): an update and review. J Am Acad Dermatol. 2016;74(6):1220–1233.

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

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