Actinic keratosis

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 Authored by: Florentia Dimitriou     ·  Teresa Deinlein     ·  Iris Zalaudek

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Author(s) Florentia Dimitriou · Teresa Deinlein · Iris Zalaudek
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Actinic keratoses (AKs) typically arise on chronically sun-damaged skin and represent the most common lesions in the spectrum of keratinocyte skin cancer. Clinically they present as multiple pink macules or papules with a variably scaly surface.

Nonpigmented actinic keratosisActinic keratosis (also called solar keratosis and senile keratosis; abbreviated as AK) is a pre-cancerous patch of thick, scaly, or crusty skin. These growths are more common in fair-skinned people and those who are frequently in the sun. They usually form when skin gets damaged by ultraviolet (UV) radiation from the sun or indoor tanning beds. AKs are considered potentially pre-cancerous; left untreated, they may turn into a type of cancer called squamous cell carcinoma. Untreated lesions have up to a 20% risk of progression to squamous cell carcinoma, so treatment by a dermatologist is recommended.

Facial skinThis glossary term has not yet been described.

Nonpigmented AKThis glossary term has not yet been described. on the faceis a central body region of sense and is also very central in the expression of emotion among humans and among numerous other species. show four dermoscopic features, allowing an accurate diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions with high sensitivity and specificity:

  • Erythema: Structureless pale-red Areas without any recognizable areas of hypopigmentation
  • Pink-to-Red pseudonetworkA structureless pigment area interrupted by non-pigmented adnexal openings: structureless red areas that resemble Network structure- small white areas correspond to follicular openings of the skin
  • Fine, wavy vesselsThis glossary term has not yet been described. (straight or coiled) surrounding the hair follicles
  • Targetoid hair follicles: Hair follicle openings surrounded by a white halo and filled with a yellowish keratotic plug (white circle surrounding a yellow clod)

Nonfacial skin

On nonfacial skin, AK usually exhibits nonspecific patterns, with features such as surface scale and keratin and dotted vesselstiny pinpoint vessels flat melanocytic lesions inflammatory diseases Bowen disease (tiny red dots densely aligned next to each other).

An additional clue to the diagnosis of AK is the rosette sign, which can only be seen with polarized lightThis glossary term has not yet been described. and consists of a white four-leaf clover-shaped structure. Although the rosette sign can be seen in actinic damaged skin and in tumors such as basal cell carcinomais the most common skin cancer, and one of the most common cancers in the United States.[1] While BCC has a very low metastatic risk, this tumor can cause significant disfigurement by invading surrounding tissues (BCCThis glossary term has not yet been described.) and melanomaThis glossary term has not yet been described., they are more commonly encountered in AK and thin SCCs.


Pigmented actinic keratosis

Pigmented variants of AK (pAK) mostly occur in darker skin phototypes. The discrimination between benignis any condition that is harmless in the long run pAK and pigmented tumors such as Lentigo maligna (LMThis glossary term has not yet been described.) may be challenging, due to the dermoscopic overlapping morphological features. The clinical differentiation from LM may be possible through palpation; pAK are most commonly having a rough texture with scaly-appearing surface and sharp border.

The reported dermoscopic characteristics of the pAK include:

  • Evident follicles: Hair follicle openings of different sizes.
  • White circles: White ring-like structures within the hair follicle. The follicle may have a targetoid appearance with central yellowish keratotic plug surrounded by a white halo
  • Grey rhomboidal structures: Grey confluent dots arranged in lines or grey-to-brown linear structures located between follicular structures


The dermoscopic differential diagnosis of pAK is supported by the presence of a prominent pseudonetwork located between keratin-filled ostial openings. The dermoscopyDermoscopy is a non invasive diagnostic method. of LM may on the other side reveal asymmetrical pigmented follicular openings and a darker dotSee [[Glossary:Dots|Dots]] located within ostial openings (some call this the isobar sign); a finding rarely seen in pAK.


The dermoscopy may help guide the best location to biopsy. Biopsying areas which reveal the most suspicious features, such as annular–granular structures, asymmetric follicular openings, dots within the ostial openings, or rhomboidal structures may provide an accuse histologic diagnosis.




References

  1. An Atlas of DermoscopyDermoscopy is a non invasive diagnostic method., Second Edition. Marghoob A. et al. CRC Press; 2012.
  2. Cuellar, F., Vilalta, A., Puig, S., et al., 2009, New dermoscopic pattern in actinic keratosis and related conditions. Arch Dermatol, 145, 732.
  3. Kittler, H., Riedl, E., Rosendahl, C. & Cameron, A., 2008, Dermatoscopys the examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. of unpigmented lesions of the skin: a new classificationis a general process related to categorization, the process in which ideas and objects are recognized, differentiated, and understood. of vessel morphologyThis glossary term has not yet been described. based on pattern analysisThis glossary term has not yet been described.. Dermatopathol Pract Conc, 14, 4.
  4. Peris, K., Micantonio, T., Piccolo, D. & Concetta, M., 2007a, Dermoscopic features of actinic keratosis. J Dtsch Dermatol Ges, 5, 970–6.
  5. Pock, L., Drlik, L. & Hercogova, J., 2007, Dermatoscopy of pigmented actinic keratosis - A striking similarity to lentigo malignaThis glossary term has not yet been described.. Int J Dermatol, 46, 414–16.
  6. Schiffner, R., Schiffner-Rohe, J., Vogt, T., et al., 2000, Improvement of early recognition of lentigo maligna using dermatoscopys the examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.. J Am Acad Dermatol, 42, 25–32.
  7. Stolz, W., Schiffner, R. & Burgdorf, W.H., 2002, Dermatoscopy for facial pigmented skin lesions. Clin Dermatol, 20, 276–8.
  8. Zalaudek, I., Giacomel, J., Argenziano, G., et al., 2006b, Dermoscopy of facial nonpigmented actinic keratosis. Br J Dermatol, 155, 951–6.
  9. Zalaudek, I., Giacomel, J., Schmid, K., et al., 2012, Dermatoscopy of facial actinic keratosis, intraepidermal carcinoma, and invasive squamous cell carcinomaThis glossary term has not yet been described.: a pro- gression model. J Am Acad Dermatol, 66, 589–97.