What is the likely diagnosis for small, raised, grayish skin lesions that can be lightly scraped off, reveal normal skin, and then recur?

Seborrheic Keratosis

The clinical description of small, raised, grayish lesions that can be scraped off with normal underlying skin and then recur is classic for seborrheic keratosis (SK), the most common benign epidermal tumor in dermatology. 1

Clinical Characteristics That Confirm the Diagnosis

• Seborrheic keratoses present as raised, well-demarcated lesions with a characteristic "stuck-on" appearance that can be lightly scraped or picked off, revealing normal skin underneath. 1
• The grayish tint you describe is consistent with the pigmentation patterns seen in SK, which can range from tan to brown to gray. 1
• Recurrence after superficial removal is expected because the lesion extends into the epidermis and will regrow if not completely removed. 1
• These lesions are biologically benign and do not require removal for medical reasons unless they become symptomatic or traumatized. 2

Critical Caveat: When Biopsy Is Mandatory

However, you must never assume a lesion is benign SK without histologic confirmation if there are any atypical features. The evidence reveals a critical pitfall:

• Melanoma can arise within seborrheic keratosis, and this combination is easily missed if the lesion is removed without pathologic examination. 3
• Squamous cell carcinoma can also develop within SK, particularly in immunosuppressed patients (19% vs 3% in non-immunosuppressed). 4
• Dermatoscopy can help differentiate SK from melanoma, but it cannot replace histopathology and should only be used by experienced clinicians. 5

When to Proceed with Clinical Diagnosis Alone

You may confidently diagnose SK clinically and observe without biopsy only if:

• The lesion has no features of the ABCDE criteria: no asymmetry, irregular borders, color heterogeneity, diameter >7mm, or recent evolution (change in size, shape, or color). 5
• There is no bleeding, inflammation, ulceration, or patient-reported pain. 5
• The patient is not immunosuppressed (especially transplant recipients, who have 10% risk of SCC within SK). 4

When Excisional Biopsy Is Non-Negotiable

If any of the following are present, you must perform complete excisional biopsy with a 2mm margin using a scalpel:

• Any change in size, color, or shape of the lesion. 5
• Asymmetry, irregular borders, or heterogeneous pigmentation. 5
• Bleeding, ulceration, or rapid growth. 5
• Patient history of immunosuppression or organ transplantation. 4

Never use cryotherapy, laser, shave biopsy, or electrocautery on a pigmented lesion without first obtaining tissue for histopathology. 5 These destructive techniques eliminate the ability to measure Breslow thickness, assess ulceration, and confirm the diagnosis—creating catastrophic consequences if the lesion is actually melanoma. 6

Treatment Options for Confirmed Benign SK

Once histology confirms benign SK, treatment is elective and based on patient preference:

• Cryosurgery is the most common removal method used by dermatologists. 2
• Other effective options include shave excision, electrodesiccation, or curettage. 2, 7
• Careful patient selection is required to optimize cosmetic results, particularly in patients with skin of color or thick/numerous lesions. 2
• No effective topical therapy currently exists for SK. 2

Bottom Line Algorithm

1. If the lesions are symmetric, uniform in color, have no recent changes, and the patient is not immunosuppressed → clinical diagnosis of SK is reasonable, and treatment is optional for cosmetic reasons. 1, 2

2. If there is any atypical feature (ABCDE criteria), recent change, or immunosuppression → excisional biopsy with scalpel is mandatory before any treatment. 5, 3, 4

3. All excised tissue must be sent to pathology—this is non-negotiable. 5