Is this hard, pigmented nodule malignant?

Case 1:
Several months earlier, this asymptomatic, pigmented, hard nodule arose on the upper arm of a 37-year-old woman.

Is this hard, pigmented nodule malignant?

    A. Pigmented basal cell carcinoma.
    B. Dysplastic nevus.
    C. Melanoma.
    D. Dermatofibroma.
    E. Epidermoid cyst.

 Answer on Next page

Lateral compression of the lesion produced a downward dimpling suggestive of a dermatofibroma, D. This often pigmented, benign fibrous nodule can mimic a melanocytic lesion. No treatment is necessary.

Pigmented basal cell carcinomas usually are not hard and bleed easily. Dysplastic nevi are not hard nodules. Desmoplastic melanomas are hard but typically do not dimple downward. Epidermoid cysts are nonpigmented, feel rounded, and reveal a central punctum, which may exude keratinaceous material with pressure.