What Is Stucco Keratosis?
Stucco keratosis is a painless, benign skin lesion that tends to develop in patients as they age. It is one of the variants of a skin condition called seborrheic keratosis. It is also known as keratosis alba. It was first described by F Ofner and E Kocsard in 1965. It is most commonly located on the feet, toes, and ankles but not on the soles. The less common sites of stucco keratosis include thighs and forearms. Stucco keratosis can develop in anyone regardless of age, but it most commonly develops in adults older than 40. In addition, it most commonly appears in males than in females.
What Causes Stucco Keratosis?
The exact cause of stucco keratosis is unknown. Some studies suggest that surface friction of the underlying epidermis can lead to the development of stucco keratosis. However, a study conducted in 2010 revealed that mutation in the PIK3CA (phosphatidylinositol - 4, 5-bisphosphonate 3-kinase catalytic subunit alpha) gene leads to the development of stucco keratosis.
It is also proposed that sunlight contributes to the development of stucco keratosis. But the fact is not completely clear since stucco keratosis lesions are not prevalent over the face region.
How Do Stucco Keratosis Skin Lesions Look Like?
The clinical features of stucco keratosis lesions include;
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The lesions clinically appear as small flat or raised keratotic papules (a small, well-demarcated bump on the skin) or plaques most commonly found on the lower extremities.
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The lesion size typically ranges from one to ten millimeters in diameter.
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The color of the lesion is generally white or gray, but sometimes the color of the lesion may vary between yellow or light tan.
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The lesion always exhibits a dry and scaly appearance that looks different from a mole.
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The lesions are mostly asymptomatic and do not cause pain or itching.
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It is more visible during the winter season as the skin becomes drier.
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It most commonly develops in elderly patients.
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The lesion does not regress on its own.
How Is Stucco Keratosis Diagnosed?
A dermatologist generally diagnoses the stucco keratosis lesions by undergoing a skin examination. A skin examination looks for the specific clinical features of stucco keratosis lesions that help diagnose the condition.
Sometimes a dermatologist will recommend a biopsy to determine whether the lesion is stucco keratosis or not. A small skin sample is scraped off from the lesion in a biopsy and sent for pathological examination. It gives a definitive diagnosis by delineating stucco keratosis from other skin conditions.
What Are the Differential Diagnoses of Stucco Keratosis?
The differential diagnoses of stucco keratosis include;
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Seborrheic Keratosis: Seborrheic keratosis is a benign skin growth that looks similar to a mole. However, unlike stucco keratosis, the color of seborrheic keratosis lesions looks dark brown or black. It can be seen more commonly over the face, scalp, abdomen, groin, shoulders, and back.
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Lichen Planus: Lichen planus is an inflammatory mucocutaneous skin condition and autoimmune disorder characterized by the pink or purplish papules on arms, legs, and oral region. It differs from stucco keratosis lesions since the lesions of lichen planus are more pruritic (itching). In addition, the presence of a white reticulated surface on the lesion makes it look different from stucco keratosis.
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Arsenical Keratosis: Arsenical keratosis is a precancerous skin condition in patients with chronic arsenic toxicity. It is characterized by hyperkeratotic plaques or papules that primarily affect the palms and soles.
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Actinic Keratosis: Actinic keratosis is a skin condition that is caused by chronic sunlight exposure. The lesions are more sessile (not free moving) with an erythematous base that makes them look different from stucco keratosis.
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Melanoma: Melanoma is a skin cancer that arises from melanocytes (pigment-producing cells that produce melanin). Melanoma lesions are differentiated from stucco keratosis using the ABCDE signs of melanoma, such as;
A - Asymmetry.
B - Borders irregularity.
C - The color difference is seen in lesions.
D - The diameter of melanoma lesions is generally greater than 6mm (millimeter).
E - Evolving of skin lesions with time.
How Is Stucco Keratosis Treated?
Stucco keratosis lesions are usually asymptomatic and do not cause discomfort to the patient; therefore, treatment is not necessary. But if the patient bothers about how it looks, then the dermatologist may suggest a few treatments such as;
1) Topical Medications: Dermatologists may prescribe topical medications that help improve the appearance of stucco keratosis lesions. It can be available in the form of easy-to-use topical lotions or ointments. Some of the common topical medications used for stucco keratosis include;
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Imiquimod 5% topical cream.
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Topical keratolytic (compounds that help soften the keratin), such as lactic acid, salicylic acid, and urea.
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12% ammonium lactate lotion.
2) Cryotherapy: Cryotherapy, also known as cryoablation or cold therapy, uses freezing or near-freezing temperatures to freeze and ablate an abnormal tissue. It is also used in the treatment of many skin conditions. Cryotherapy for stucco keratosis lesions uses liquid nitrogen to freeze the lesion, and the lesions fall off after a few days of cryotherapy. The freeze cycles depend on the thickness of the lesion, and generally, two freeze cycles for three to ten seconds are required. The treatment usually does not cause any side effects, but sometimes skin ulceration can occur if deep freezing of lesions is done.
3) Curettage: The dermatologist may suggest a curettage to remove the stucco keratosis lesions. In curettage, the lesions are generally scrapped off using a curette (a small surgical instrument used for scrapping lesions). It does not cause any bleeding, but the dermatologist may suggest topical antibiotic cream after curettage to reduce the risk of infection.
Loss of skin pigmentation may occur as a consequence of the treatments.
Do Stucco Keratosis Lesions Cause Any Harm?
Stucco keratosis lesions are harmless, and they do not cause any severe discomfort to the patients. The lesions are always benign (noncancerous) and do not cause any symptoms in individuals. In addition, they are not contagious; therefore, the patient should avoid the fear of the spread of lesions to different body parts or other people.
Conclusion
Stucco keratosis lesions are benign and asymptomatic; therefore, they do not require any treatment. But the dermatologist may suggest completely removing lesions only if the patient desires. The treatments for stucco keratosis include topical medications, cryotherapy, and curettage. These treatments help improve the appearance of the lesion; however, they do not provide any cure nor prevent any formation of new lesions.
