The term “barnacles on humans” is a colloquial phrase describing a common, non-cancerous skin growth, not an actual infestation by marine organisms. True barnacles are crustaceans that cement themselves permanently to hard surfaces like rocks, ships, and whales; they do not attach to human skin. The popular, though medically inaccurate, nickname stems from the visual similarity between these growths and the rough, clustered appearance of barnacles on a ship’s hull. The condition people are typically searching for is a benign growth known as Seborrheic Keratosis (SK). This misnomer persists because the growths often look like they have been stuck or pasted onto the skin’s surface, mimicking the firmly attached shell of a barnacle.
The Common Skin Growth Mistaken for Barnacles
The actual skin condition is Seborrheic Keratosis (SK), one of the most frequently observed non-cancerous skin tumors, especially in older adults. These growths are characterized by a dull, waxy, or rough surface texture, often described by dermatologists as having a distinctive “stuck-on” look. SK color varies widely, presenting as light tan, brown, black, yellow, or gray.
They range in size from millimeters to over an inch across, and an individual may develop a single lesion or hundreds over time. While they can appear almost anywhere, they commonly aggregate on the face, scalp, neck, chest, and back, but not on the palms or soles of the feet. SK represents a slow, gradual overgrowth of keratinocytes, the most common type of skin cell. Their prevalence is high, with over half of all adults expected to develop at least one growth in their lifetime.
Causes and Characteristics of These Growths
The primary risk factor for Seborrheic Keratoses is age, leading to the nickname “barnacles of aging.” They rarely appear before middle age, and their number and size increase substantially after age 50. Genetic predisposition is also a significant factor, as these growths often run in families.
Specific genetic mutations, such as those involving the Fibroblast Growth Factor Receptor 3 (FGFR3) gene, have been identified, indicating a cellular mechanism for their formation. Sun exposure is correlated with their occurrence, particularly on the face and upper trunk, but SK can also develop on covered areas of the body. This suggests UV radiation is a contributing factor, but not the sole cause.
SK is generally asymptomatic, causing no discomfort, but lesions can become irritated, itchy, or bleed if rubbed by clothing or jewelry. Specialists differentiate SK from potentially cancerous lesions like melanoma by noting their regular borders, uniform appearance, and “stuck-on” look. Any growth that changes rapidly, has irregular borders, or contains multiple colors should be examined promptly.
Management and Removal Procedures
Since Seborrheic Keratoses are benign, treatment is not medically necessary unless they become chronically irritated or the patient requests removal for cosmetic reasons. Removal procedures are typically simple, in-office procedures performed by a dermatologist.
Removal methods include:
- Cryotherapy: Liquid nitrogen is applied to freeze and destroy the cells. The treated lesion scabs and falls off within a few weeks, though a temporary or permanent light spot may remain.
- Curettage: The lesion is scraped off the skin surface using a specialized surgical instrument called a curette after the area has been numbed.
- Electrodesiccation: This method uses a targeted electrical current to burn and destroy the tissue, often combined with curettage.
- Laser therapy: Ablative lasers offer precise removal with potentially superior cosmetic results, especially for multiple or difficult-to-reach lesions.