A 26-year-old woman comes to the physician for evaluation of a lesion on her left foot. She initially noticed a small bump 6-7 months ago that has gradually become firm and slightly pigmented. She has no pain or itching around the site and has no other medical conditions. The patient has no history of tobacco or alcohol use. She works as an accountant. Her temperature is 36.1 C (97 F), blood pressure is 128/76 mm Hg, and pulse is 78/min. Skin examination (shown below) reveals a 0.8 cm hyperpigmented nodule with dark edges. There is a central dimple that develops when the lesion is pinched at the edges. The remainder of her physical examination is within normal limits. Which of the following is the most likely diagnosis?

Question

A 26-year-old woman comes to the physician for evaluation of a lesion on her left foot.  She initially noticed a small bump 6-7 months ago that has gradually become firm and slightly pigmented.  She has no pain or itching around the site and has no other medical conditions.  The patient has no history of tobacco or alcohol use.  She works as an accountant.  Her temperature is 36.1 C (97 F), blood pressure is 128/76 mm Hg, and pulse is 78/min.  Skin examination (shown below) reveals a 0.8 cm hyperpigmented nodule with dark edges.  There is a central dimple that develops when the lesion is pinched at the edges.  The remainder of her physical examination is within normal limits.  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

This patient's skin lesion is consistent with a dermatofibroma (DF), which is due to fibroblast proliferation causing isolated or multiple lesions, most commonly on the lower extremities. The etiology is unknown, but some patients may develop lesions after trauma or insect bites. Typical lesions are nontender and appear as discrete, firm, hyperpigmented nodules that are usually <1 cm in diameter. The lesions have a fibrous component that may cause dimpling in the center when the area is pinched ("dimple" or "buttonhole" sign). Diagnosis of DF is made clinically based on the appearance of the lesion. Treatment (cryosurgery or shave excision) is usually not required unless the lesion is symptomatic, bleeds, or changes in color or size. Patients may also request treatment for cosmetic reasons or because of recurrent cuts when shaving the legs. (Choice A) Basal cell carcinoma is the most common type of skin cancer and presents as a pearly nodule with small telangiectasias in sun-exposed areas. Although it can be pigmented, basal cell carcinoma does not dimple in the center when pinched and is uncommon in young patients. Basal cell carcinoma (Choice C) Kaposi sarcoma is due to human herpesvirus-8 (HHV-8) and is frequently seen in immunocompromised patients (especially AIDS-related). Lesions are typically multicentric, red, purple, or brown macules, plaques, or nodules that can appear on the trunk, extremities, or face. Kaposi sarcoma (Choice D) Pyogenic granuloma is a benign vascular skin tumor that presents as a small red papule that grows rapidly over weeks or months to a pedunculated or sessile shiny mass. The lesions most commonly occur on the lip and oral mucosa and can bleed with minor trauma. Pyogenic granuloma (Choice E) Squamous cell carcinoma is the second most common skin cancer and usually occurs on sun-exposed areas. Typical lesions are firm and scaly papules, plaques, or nodules that do not usually have a central dimple with pinching. Squamous cell carcinoma Educational objective: Dermatofibromas are nontender, firm, hyperpigmented nodules that are usually <1 cm in diameter. They are due to fibroblast proliferation and most commonly occur on the lower extremities. The lesions have a fibrous component that causes the central area to dimple when pinched. References: Dermatofibroma: a possible model of local fibrosis with epithelial/mesenchymal cell interaction (http://www.ncbi.nlm.nih.gov/pubmed/19175704)

A 26-Year-Old Woman Comes to the Physician for Evaluation of a Lesion