Makindo Medical Notes

Epidemiology

• Rare in individuals under the age of 30: Seborrheic keratosis is uncommon in younger individuals.
• Incidence increases with age: The condition is more frequently diagnosed in older adults, particularly those over 40.
• Genetic factors: Seborrheic keratosis often follows an autosomal dominant inheritance pattern, meaning it can run in families, increasing the likelihood of multiple lesions in affected individuals.

Clinical Presentation

• Characteristic appearance: The lesions typically present as well-defined, waxy papules or plaques with a "stuck-on" appearance, making them easily recognizable.
• Variation in presentation: Seborrheic keratosis can vary in color (from light tan to black), size (from small to several centimeters), and shape (round or oval). They may become more warty, greasy, and pigmented over time.
• Common sites: Lesions are most often found on the face, trunk, and upper extremities. However, they can develop on nearly any part of the body, except for the palms and soles, which are typically spared.

Pathophysiology

• Benign epithelial tumour: Seborrheic keratosis is a common, benign epithelial tumour arising from the outer layer of the skin. It is considered non-cancerous.
• Growth pattern: The tumours develop due to the abnormal proliferation of basal keratinocytes, leading to the formation of lesions on the skin's surface.

Differential Diagnosis

Several skin conditions can resemble seborrheic keratosis, so it’s crucial to differentiate them for proper management. These conditions include:

• Malignant melanoma: Particularly lentigo maligna and nodular melanoma, which can appear similar to seborrheic keratosis but are malignant and require immediate attention.
• Melanocytic nevi: These are benign moles that may resemble seborrheic keratosis, especially if they have irregular borders or color.
• Pigmented basal cell carcinoma: Basal cell carcinoma may mimic seborrheic keratosis due to its pigmentation, but it often presents with more irregular borders and growth patterns.
• Solar lentigo: Also known as age spots, these lesions may resemble seborrheic keratosis but usually appear as flat, pigmented areas with a uniform color.
• Spreading pigmented actinic keratosis: Actinic keratosis can appear similar to seborrheic keratosis, especially in areas of sun-damaged skin.

Investigations

• Clinical Diagnosis: Seborrheic keratosis is usually diagnosed based on its characteristic appearance and clinical features, so biopsy is not typically required.
• Biopsy: A skin biopsy may be performed if there is any doubt about the diagnosis or concern for malignancy. A biopsy is helpful in distinguishing seborrheic keratosis from other skin conditions with similar appearances.
• Dermatoscopy: Dermatoscopic examination may be used to evaluate the lesion in more detail, especially when the diagnosis is unclear.

Management

Most cases of seborrheic keratosis do not require treatment unless the patient has cosmetic concerns or the lesions cause discomfort. Treatment options include:

• Liquid nitrogen cryotherapy: A common and effective method for freezing off seborrheic keratosis lesions. The procedure is quick, though it may cause temporary redness or swelling.
• Curettage: The lesion is scraped off using a specialized instrument under local anesthesia. This method is particularly useful for raised lesions.
• Electrosurgery: In some cases, electrosurgical excision may be used to remove the lesion, especially when it is difficult to remove by curettage.
• Laser therapy: Some patients may benefit from laser treatment, which can be used for larger or more resistant lesions, offering a less invasive option for removal.
• Topical treatments: In certain cases, topical agents such as 5-fluorouracil or imiquimod may be prescribed, although these are not as commonly used for seborrheic keratosis as for other skin conditions like actinic keratosis.
• Observation: If the lesions are asymptomatic, non-cancerous, and not a cosmetic concern, a watchful waiting approach may be recommended.