Keratolysis refers to the softening or breakdown of the skin’s outermost layer, the stratum corneum, which is composed primarily of the protein keratin. This process leads to distinct visual changes in the skin’s texture and appearance. This article focuses on the two most commonly encountered presentations: Pitted Keratolysis and Keratolysis Exfoliativa. Understanding the specific visual signs of each is the first step toward proper identification and management.
The Distinct Appearance of Pitted Keratolysis
Pitted Keratolysis (PK) is identified by small, crater-like depressions on the soles of the feet. These pits are described as “punched-out” erosions, typically measuring between 1 and 7 millimeters in diameter. The condition most frequently affects the pressure-bearing areas of the foot, such as the heel and the ball of the foot, and often involves both feet.
The affected skin often appears white or grayish, particularly when moist (maceration). The tiny pits may cluster together, creating larger, irregular, and shallow areas of erosion. A significant non-visual symptom accompanying PK is a strong, foul odor, often the first sign noticed. This smell results from bacteria producing sulfur compounds as they break down keratin. The condition is generally asymptomatic, meaning it does not cause pain or itching.
Visual Differences of Keratolysis Exfoliativa
Keratolysis Exfoliativa (KE) presents a different visual picture, mainly affecting the hands, though the soles of the feet can also be involved. The condition begins with the formation of small, superficial blisters that contain air rather than fluid. These initial lesions are typically white or yellowish macules that rupture easily.
Once these blisters rupture, they leave behind characteristic circular or oval areas of peeling skin. The peeling involves the superficial layer of the epidermis, often creating a fine, curled rim of shed skin around the edges, known as collarette scaling. The underlying skin may appear slightly red, shiny, or feel tight and mildly sore. This superficial peeling occurs repeatedly, often in cycles, distinguishing KE from the deep pitting of PK.
Underlying Triggers and Risk Factors
The visual symptoms of Pitted Keratolysis are a direct consequence of a bacterial infection, most commonly caused by species like Corynebacterium and Kytococcus sedentarius. These bacteria thrive in environments characterized by excessive moisture and occlusion. Hyperhidrosis (excessive sweating) is a major predisposing factor, creating the warm, damp conditions the bacteria require to multiply.
The bacteria produce protein-digesting enzymes called proteases, which break down the keratin in the stratum corneum, creating the microscopic divots visible as pits. Wearing tight or non-breathable footwear for extended periods traps moisture and significantly increases the risk.
Keratolysis Exfoliativa is not caused by a specific infection, and its exact cause remains unknown. It involves a premature separation of skin cells in the outer layer. Its onset is strongly associated with environmental triggers, including frequent exposure to water, harsh soaps, detergents, and other chemical irritants.
Strategies for Management and Prevention
Management for Pitted Keratolysis focuses on eliminating the bacteria and reducing moisture. Topical antibiotics, such as clindamycin, erythromycin, or fusidic acid, are commonly prescribed to eradicate the causative organisms. Concurrently, managing hyperhidrosis with topical antiperspirants, such as those containing aluminum chloride, is necessary to remove the bacterial growth environment.
Preventing the recurrence of PK involves rigorous foot hygiene, including washing the feet twice daily and ensuring they are thoroughly dried, especially between the toes. Wearing moisture-wicking or wool socks and changing them frequently is advised. Alternating footwear ensures shoes have time to air out and dry completely.
For Keratolysis Exfoliativa, the primary strategy is to protect the hands from irritants like soaps and detergents, often requiring wearing gloves for household tasks. Frequent application of rich emollients and moisturizers is recommended to support the skin barrier function and relieve the dryness that follows the peeling.