Actinic keratosis is a chronic skin disease characterized by intraepithelial dysplasia, atypia of keratinocytes. The pathology is localized in areas of the skin exposed to sun exposure and occurs after prolonged natural or artificial ultraviolet radiation in genetically predisposed people. Solar keratosis is considered a predictor of skin carcinogenesis and often precedes invasive squamous cell skin cancer. All this determines the relevance of dermatoscopy for timely diagnosis of dermatosis and determination of tactics.
- Clinical forms of actinic keratosis
- Features of dermatoscopy dermatosis: pigmented and non-pigmented forms
Clinical forms of actinic keratosis
Typical erythematous form of actinic keratosis is characterized by the development of single or grouped foci in the form of spots or papules of irregular shape ranging in size from 0.3 cm to 3–5 cm. Such skin lesions are covered with keratinized, tightly attached scales. Color ranges from pale pink to brownish red. With erythematous form lesions are localized on the forehead, in the area of the nose, temples, auricles, on the red border of the lips, lateral surface of the skin, forearm, hands, anterior surface of the lower leg.
Fig.1 Classical form of actinic keratosis
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For hypertrophic form actinic keratosis is characterized not only by chronic influence of ultraviolet radiation, but also by chronic irritation – constant friction. Skin lesions in this form are localized on the back of the hands, skin of the face and on the skin of the scalp. One of its manifestations is the appearance of a dense keratinous mass above the surface of the skin.
Randomized trial of four approaches to the treatment of actinic keratosis
In the proliferative form histologically hyperkeratosis with foci of parakeratosis prevails, slight papillomatosis is observed, less often – thickening of the granular layer.
Epithelial cells lose their polarity, are characterized by polymorphism and atypia.
Lichenoid actinic keratoses are lichenoid papules red or red-beige that tend to coalesce. Histologically, the lichenoid form is characterized by a pronounced lymphocytic infiltrate in the superficial layers of the dermis.
Acantholytic keratosis clinically resembles seborrheic keratosis in the form of light brown flat lesions that have a finely warty surface.
Seborrheic keratosis: clinical manifestations, diagnosis
Bovenoid form of actinic keratosis is characterized by acanthosis with continuation and thickening of epidermal outgrowths, hyperkeratosis, focal prakeratosis.
In the presence of atrophic form of the disease, histologically, atrophy of the epidermis, atypia of cells of the basal layer.
Features of dermatoscopy of dermatosis: pigmented and non-pigmented forms
The characteristic dermoscopic signs of non-pigmented forms of actinic keratosis are:
- Erythema, which is represented by thin linear-wavy vessels, surrounding the openings of the hair follicles and forming a pink-red pseudo-network;
- White-yellow superficial scales;
- In the hypertrophic variant, the openings of the hair follicles are filled with yellowish keratotic plugs and are surrounded by a white halo – target-like structures.
Fig.2 A) pink-red pseudonetwork, B) surface scales, C) target-like structures.
In pigmented form of actinic keratosis, the following signs are observed during dermatoscopy:
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- Many grey and dark brown dots and globules surrounding hair follicle openings. Histologically, this pattern corresponds to a cluster of macrophages loaded with melanin located in the upper part of the dermis;
Fig.3 A) gray-brown dots and globules, B) annular granular structures. C) gray-brown pseudo-network.
- Dots and globules are able to merge, forming annular granular structure;
- Gray Brown Pseudo-Network.
The pathognomonic feature that characterizes the non-pigmented form of actinic keratosis is the "strawberry pattern".
This is a pseudo-reticular structure of pink or red color, localized between the follicular openings, which are surrounded by a white halo.
Actinic Keratosis Treatment Tactics
The "strawberry pattern" is thought to be due to the bipolar optical refraction of keratin in the actinic keratosis lesion.
The use of dermatoscopy in the diagnosis of actinic keratosis as a modern highly informative method for non-invasivediagnosis of neoplasms and precancerous skin diseases, makes it possible to reliably establish clinical diagnosis at an early stage.
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