From the Guidelines
Seborrheic keratosis can be described on physical examination as a well-demarcated, waxy, stuck-on appearing growth on the skin. These lesions typically range from light tan to dark brown or black in color, have a rough, warty, or velvety texture, and vary in size from a few millimeters to several centimeters 1. They often have a characteristic "greasy" feel and may display a "pasted-on" appearance as if they could be easily scraped off. Seborrheic keratoses commonly feature small keratin-filled cysts called horn cysts that appear as tiny white or yellow dots on the surface. The lesions may be flat or raised, with some having a verrucous or papillomatous surface. They frequently occur on sun-exposed areas such as the face, neck, shoulders, and back, but can appear anywhere except the palms and soles. Multiple lesions are common, especially in older individuals. Unlike melanoma, seborrheic keratoses typically have regular, well-defined borders and do not change rapidly in appearance 1. These benign growths result from the proliferation of epidermal cells and tend to become more numerous with advancing age. It's worth noting that seborrheic keratosis can be distinguished from other skin lesions such as actinic keratosis, with which it can be confused, especially in the context of sun-damaged skin 1. Key characteristics to look for in differentiating seborrheic keratosis from other lesions include its stuck-on appearance, color variation, and the presence of horn cysts. Given the potential for confusion with more serious skin conditions like melanoma or squamous cell carcinoma, a thorough physical examination and, when necessary, diagnostic procedures such as biopsy are crucial for accurate diagnosis and appropriate management.
From the Research
Physical Examination of Seborrheic Keratosis
Seborrheic keratosis (SK) can be described on physical examination as a common benign epidermal tumor with various clinical presentations. The key characteristics of SK include:
- Occurrence on all areas of the body except for the palms and soles, with the most common sites being the face and upper trunk 2, 3
- Remarkable variability in clinical presentation, raising some differential diagnoses 3
- Different subtypes based on clinical presentation and histologic findings 2, 4
- Increasing incidence with age and exposure to ultraviolet light 3, 5
Clinical Presentation
The clinical presentation of SK can vary, but it is usually characterized by:
- A benign epidermal tumor with a pigmented or non-pigmented appearance 4
- A lesion that can be flat or raised, with a smooth or rough surface 5
- A lesion that can occur singly or in multiple numbers, with a range of sizes and colors 2
Diagnostic Techniques
The diagnosis of SK is usually made clinically, but can also be aided by: