TELEDERMATOLOGY READER REPORT1
History
Chief complaint
Presenting for diagnosis of a lesion.
History of present illness
A 50-year-old man presents with a "scaly pink spot" on his lower leg that he believes has been present for about 6 months. Prior treatment: none. His primary symptom: This lesion is asymptomatic. Prior biopsy: none. He has no personal or family history of skin cancer or melanoma. Other significant laboratory/study findings: none.
Image Quality Assessment
Fully satisfactory.
TELEDERMATOLOGY IMAGING READER REPORT
One image was provided that shows a solitary annular hyperkeratotic plaque with a hypopigmented glassy center involving the lower leg. The plaque is separated from normal skin by a distinctive raised ridge-like scale with a thin furrow in the middle.
INTERPRETATION OF IMAGES
Lesion A
Findings
The presented lesion (see Figure 1) shows a glassy center (suggestive of mild atrophy) and distinctive hyperkeratotic ridge (suggestive of a coronoid lamella). These findings, along with the history, are most consistent with the diagnosis of a porokeratosis.
RECOMMENDATIONS
Skin Care and Treatment Recommendations
We recommend reassurance of the benign nature of this lesion to the patient. There is a very low risk of malignant potential so sun protection and watching for changes of malignant degeneration should be discussed. Per patient preference, if treatment is requested, light cryotherapy can be performed on this solitary lesion, or 5-fluorouracil cream can be used twice daily until a brisk inflammatory reaction occurs.
RECOMMENDED FOLLOW-UP
Type of Visit
Return to primary provider for reassurance and to discuss treatment, if patient would like to pursue treatment.
CLINICAL PEARL
Porokeratosis initially begins as a scaly papule that spreads outward. Over time, it often becomes annular with an atrophic center and develops a peripheral keratotic ridge. This keratotic ridge correlates with the hallmark finding histologically, which is the coronoid lamella. The coronoid lamella shows evidence of localized keratinocyte dysplasia, which suggests that porokeratosis is because of an expanding clone of abnormal keratinocytes (Sertznig, von Felbert, & Megahed, 2012). Because the coronoid lamella is the principal feature seen with pathology, the edge of a lesion must be included in a biopsy for diagnosis.
There are multiple variants of porokeratosis that can be distinguished based on clinical features and a thorough history. Classic porokeratosis of Mibelli is usually a larger singular lesion sometimes associated with immunosuppression and often on the extremities. Disseminated superficial actinic porokeratosis is the most common variant and usually presents in adults with multiple lesions on sun-exposed skin. Linear porokeratosis is usually seen in children with lesions distributed along Blaschko's lines. Porokeratosis palmaris et plantaris disseminata presents with small uniform hyperkeratotic papules on the palms and soles, which can sometimes be generalized or on the mucosa (Spencer, 2014). There are also many more variants of porokeratosis, which are beyond the scope of this article and rarely seen in clinical practice.
Porokeratosis is generally considered to be a benign condition, but development of squamous cell carcinoma in long-standing lesions can occur. The highest risk of malignant degeneration is found in linear porokeratosis, and disseminated superficial actinic porokeratosis has the lowest risk. Treatment of porokeratosis is challenging and often unnecessary given the benign nature. If treatment is required, light cryotherapy or application of 5-fluorouracil cream should be considered. To avoid recurrence, destruction of the abnormal clone of keratinocytes is required (Requena, Requena, & Cockerell, 2012). If an area is suspected to have malignant changes, a biopsy followed by an appropriate surgical excision should be performed.
REFERENCES