Pigmented Basal Cell Carcinoma Masquerading as a Melanoma

Abstract

Basal cell carcinoma is the most common skin cancer. Pigmented basal cell carcinoma is an uncommon clinical presentation that can resemble a melanoma. We present the clinical and pathologic features of three individuals whose pigmented basal cell carcinomas masqueraded as melanomas. All of the patients were Hispanic and ranged in age from 63 years to 77 years. They presented with a pigmented lesion that was ultimately diagnosed as a pigmented basal cell carcinoma; one woman had a collision tumor consisting of a pigmented basal cell carcinoma and a seborrheic keratosis. All of the patients had their tumors removed using Mohs micrographic surgery, without recurrence. The clinical differential diagnosis of a black tumor-particularly in patients with darker skin types-should include pigmented basal cell carcinoma in addition to melanoma; a biopsy of the lesion will establish the diagnosis.

Keywords: basal; carcinoma; cell; collision; masquerading; melanoma; mimic; nodular; pigment; pigmented.

Figure 1. Pigmented basal cell carcinoma on the nasal tip mimicking melanomas

Views of the basal cell carcinoma (within the black circle) prior to biopsy, from the right side (A), frontal (B), and left side (C), of the nasal tip of a 74-year-old Hispanic woman demonstrate an ulcerated (blue arrows), black nodule (black arrows). A paramedian forehead flap was used to repair the wound following Mohs micrographic surgery; the right side (D), frontal (E), and left side (F) of her nasal tip show excellent healing of the flap (within red circle) and hypertrichosis (white arrows) from the tissue used to cover the surgical defect.

Figure 2. Pigmented basal cell carcinoma on the left nasal bridge mimicking melanoma

Distant (A), closer (B and C), frontal (A and B), and left side (C) views of a pigmented basal cell carcinoma (within the black circle) on the left nasal bridge of a 63-year-old Hispanic man. The tumor consists of black pigment (black arrows) adjacent to ulcerated (blue arrow) and intact red and flesh-colored areas.

Figure 3. Pigmented basal cell carcinoma (with concurrent seborrheic keratosis) masquerading as melanoma.

Distant (A) and closer (B and C) views of a collision tumor consisting of a pigmented basal cell carcinoma that presented as a large ulcerated black nodule (black arrow) and a seborrheic keratosis (orange arrows) appearing as pigmented patches adjacent to the centrally located black nodule on the left breast of a 77-year-old woman. Distant (D) and closer (E) views of the left breast following a layered closure (white arrows) of the surgical wound. The tumor was cleared after one stage of Mohs micrographic surgery.