Stucco Keratosis 

Updated: May 17, 2017
Author: Katherine H Fiala, MD; Chief Editor: Dirk M Elston, MD 

Overview

Background

Stucco keratosis was first described by Kocsard and Ofner in 1965 and later by Willoughby and Soter in 1972.[1, 2]

Stucco keratosis is a keratotic papule that is usually found on the distal lower acral extremities of males. Stucco keratosis seems to appear with a higher frequency in males.

Usually, multiple lesions are found in stucco keratosis; in one study, between 7 and more than 100 lesions were noted on the patients. The lesion is asymptomatic, and patients usually do not complain of having the lesions. The name stucco keratosis is derived from the "stuck on" appearance of the lesions.

Pathophysiology

Stucco keratosis appears to be produced by thickening of the epidermis. On microscopic examination, the epidermis is usually exophytic with a church spire–like appearance. The surface may be regularly distributed into folds with elongation of papillae. The stratum corneum is thickened.

Surface friction may contribute to the development of stucco keratosis lesions. The tumor grows outward and does not penetrate into the dermis. The lesions are usually found in elderly patients.

With a nested polymerase chain reaction technique, human papillomavirus types 9, 16, 23b, DL322, and 37 were detected in a 75-year-old nonimmunosuppressed man with very extensive stucco keratosis lesions.[3] This finding requires confirmation in other patients.

Various genetic mutations, including PIK3CA and FGFR3 have been reported in common seborrheic keratoses.[4] A 2010 study demonstrated that three of five stucco keratosis samples revealed a PIK3CA mutation, but not the FGFR3 mutation.[5] Further study will likely highlight the genetic background for stucco keratoses.

Epidemiology

Frequency

The incidence of stucco keratosis is approximately 10% of the senior population in the United States. Stucco keratosis predominantly occurs in elderly men.

Race

Stucco keratosis is found in persons of all races. No reports have been noted on race as a factor in stucco keratosis.

Sex

The incidence of stucco keratosis is higher in males than in females.

Age

Elderly people are susceptible to stucco keratosis. The stucco keratosis lesions begin to appear around age 45 years.

Prognosis

The lesions of stucco keratosis are benign growths similar to those of seborrheic keratosis. Clinically, stucco keratosis lesions may be mistaken as a melanoma.

Patient Education

Patients with stucco keratosis can be informed that the lesions are not cancerous. Because lesions are found in elderly patients, the patients can be taught the "ABCDEs" of melanoma.

 

Presentation

History

Stucco keratosis is a benign lesion that is best regarded as a form of seborrheic keratosis. Stucco keratosis lesions are often seen in elderly men. The stucco keratosis lesions are asymptomatic and usually go unnoticed by both the patient and the clinician.

Physical Examination

Stucco keratosis lesions appear as keratotic papules or plaques on the lower extremities but are sometimes found on the upper extremities, usually acrally. The lesions are typically less than 1 centimeter in size and are usually white in color.  Note the image below. If the lesion is removed by curetting, a peripheral collarette of scale is sometimes left.

Stucco keratosis in a 70-year-old male veteran. A Stucco keratosis in a 70-year-old male veteran. A few scattered white plaques are on the lower extremity.

Causes

No known cause of stucco keratosis has been reported. The epidermis is hyperplastic and usually exophytic with no dysplasia. This is similar to what is seen in seborrheic keratosis.  

Various genetic mutations, including PIK3CA and FGFR3 have been reported in common seborrheic keratoses.[4] A 2010 study demonstrated that three of five stucco keratosis samples revealed a PIK3CA mutation, but not the FGFR3 mutation.[5] Further study will likely highlight the genetic background for stucco keratoses.

 

DDx

Diagnostic Considerations

Hard nevus of Unna has a similar histopathologic feature of a saw tooth epidermis. The term hard nevus is not used anymore in the literature but could be a term that includes what is described as stucco keratosis.[6, 7, 8]

Actinic keratoses are typically spinier, less sessile, and often have an erythematous base.

Lichen planus papules are more violaceous and pruritic and may have Wickham striae, which is a reticulated white surface.

Arsenical keratoses arise on the palms and soles of acral surfaces rather than the dorsal surfaces.

Differential Diagnoses

 

Workup

Approach Considerations

No laboratory or imaging studies are required in stucco keratosis. If the diagnosis is in question, then a shave biopsy can be performed to confirm the diagnosis.

Histologic Findings

A church spire–like epidermal hyperplasia similar to that in hyperkeratotic seborrheic keratosis is seen, as in the image below.

Photomicrograph of characteristic church spires of Photomicrograph of characteristic church spires of stucco keratosis.
 

Treatment

Medical Care

Stucco keratosis is a benign lesion that can be removed by curettage or cryotherapy.

Different methods or a combination of methods can be used to remove the stucco keratosis lesions. The most common methods in practice are liquid nitrogen therapy and curettage.

Liquid nitrogen therapy in stucco keratosis

Lesions can be frozen with liquid nitrogen by either the spray method or the dipstick method. Because the lesions are benign, the required temperature of the lesion should reach -25°C.

Depending on the thickness of the lesion, two freeze cycles of 3-10 seconds are usually required. The lesions fall off in a few days, and, if the procedure is not successful, liquid nitrogen therapy may be repeated. Ambient temperature and skin temperature, as well as underlying vascularity, must be taken into account. Ulceration can occur if cryotherapy is too vigorous.

Curettage in stucco keratosis

Stucco keratosis can be removed by curettage. Lesions can be removed by gentle scraping. Once the lesion is removed, topical petrolatum can be applied.

Other methods used in stucco keratosis

The lesion can be removed by using an electrodesiccator.

Shave removal is performed only if the lesion appears malignant, does not respond to cryotherapy and/or curettage, or requires a definitive diagnosis.

Surgical Care

No surgical care is required in stucco keratosis.

Long-Term Monitoring

Patients with stucco keratosis should be advised to have a periodic skin examination.

 

Medication

Medication Summary

No medical therapy is required in stucco keratosis.