Seborrheic Keratoses in Elderly People

A 75-year-old man complained of the sudden appearance of multiple “moles” on his back. He had no history of skin cancer. Past medical history was significant for prostate cancer, which had been diagnosed and treated 2 years previously.

Physical examination of the trunk showed multiple well-demarcated, light and dark brown warty papules and plaques with a “stuck on” appearance, consistent with seborrheic keratoses. A total body skin examination revealed no lesions suspicious for skin cancer.

Seborrheic keratoses are extremely common, benign epidermal lesions that usually develop in later life, often in large numbers, primarily on the trunk and face. They typically appear verrucous; patients often report that portions of the lesions have been readily scraped or rubbed off with a fingernail or towel. Some seborrheic keratoses demonstrate cystic openings plugged with horny material. The lesions range in color from tan to light or dark brown; lesions that have been traumatized by picking or irritation from clothing may appear crusted or pink and inflamed.

A variant of seborrheic keratosis called dermatosis papulosa nigra is especially common in blacks, often appearing in early adulthood. This condition manifests clinically as multiple minute, warty dark brown papules, often around the zygomatic bone. Another variant is stucco keratosis; it usually affects the distal extremities and is characterized by flat, white to gray, hyperkeratotic papules.

The sudden appearance of multiple seborrheic keratoses in patients thought to have an underlying internal malignancy is referred to as the sign of Leser-Trlat. Most experts now discount this sign for several reasons: both malignancy and seborrheic keratoses are common in the elderly; the patient's history of sudden onset of the keratoses may not be accurate; and reviews of cases in the literature where there appeared to be a true association of sudden-onset multiple pigmented warty lesions and an internal malignancy suggest that the patients had acanthosis nigricans (velvety, hyperpigmented plaques affecting the neck and axillae, sometimes in association with warty tan and brown skin tags), rather than seborrheic keratoses.

Seborrheic keratoses require no treatment, although patients often request treatment for cosmesis.

Options include cryotherapy, electrosurgery, curettage, and shave removal. However, it is recommended that one of the latter two modalities-which allow for histopathologic examination of the lesion-be used, since the differential diagnosis includes malignant melanoma. Other entities that must be considered in the differential diagnosis of seborrheic keratoses include benign melanocytic nevi and pigmented basal cell carcinoma.