Benign brown-black and pigmented skin growths

10: Benign brown-black and pigmented skin growths


The vast majority of brown-black skin growths are benign; however, they are frequently a cause for concern among patients who believe they may have a malignant melanoma. The ability to recognize common benign brown-black skin growths can spare patients anxiety and the scar from a biopsy. This chapter reviews common brown-black skin growths that are not discussed elsewhere in this book.

Key terms:

seborrheic keratosis

café au lait macules


congenital melanocytic nevus

acquired digital fibrokeratoma

blue nevus

Seborrheic keratoses

Layla Kazemi and Afton Chavez

Clinical features

Differential diagnosis

The differential for SKs includes solar lentigo, verruca vulgaris, condyloma acuminatum, Bowen disease, squamous cell carcinoma (SCC), melanocytic nevus, melanoma, acrochordon, and tumor of the follicular infundibulum.


Initial steps in management

Warning signs/common pitfalls


You have seborrheic keratoses, which are very common benign skin lesions. They are seen in nearly all older individuals. You will likely continue to develop more throughout your lifetime and there is no way to prevent this, but they are not contagious or dangerous. The cause of seborrheic keratoses is unknown, but they seem to run in families and studies suggest that sun exposure may play a role.

Seborrheic keratoses are usually asymptomatic; however, they can become itchy and inflamed, and catch on clothing. If your lesions become symptomatic or you would like them removed for cosmetic reasons, there are options available. The most common option is cryosurgery, which involves freezing the lesion with liquid nitrogen. They can also be removed under local anesthesia by scraping the lesion from the skin or cutting it off with a small, flat blade. Their removal should cause minimal scarring, but the skin may be lighter than the surrounding area; this can either fade with time or stay permanently.

If you notice any changes in your lesions or a sudden increase in their number, you should make an appointment with a dermatologist so they can be reexamined.

Acquired digital fibrokeratoma

Erisa Alia and Philip E. Kerr

Clinical features

Acquired digital fibrokeratoma (ADFK) is a relatively rare, benign, fibroepithelial tumor with a predilection for the fingers and toes. Occasionally, it can be found on the dorsum of the hand, elbow, prepatellar area, nail bed, and heel. ADFK presents as small, firm, solitary, skin-colored to pink, exophytic papulonodules. Its surface is hyperkeratotic, and it is surrounded by a characteristic collarette of slightly raised skin at its base. ADFK is usually asymptomatic.

It has a tendency to gradually increase in size and occurs more often in middle-aged adults. The etiology remains unknown; however, trauma to the site may be contributory.

Differential diagnosis

ADFK is most commonly diagnosed based on history and physical examination. Nevertheless, to predict the response to treatment, it is important to differentiate ADFK from other cutaneous lesions in the differential diagnosis. These include verruca vulgaris (the common wart), supernumerary digits, periungual/subungual fibroma, and pyogenic granuloma (PG).

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Jul 22, 2021 | Posted by in Dermatology | Comments Off on Benign brown-black and pigmented skin growths

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