Treating Hyperkeratotic Skin Conditions
Keralyt® (Salicylic Acid)
The normal functions of the skin include providing a barrier to protect the body from dehydration and environmental insults, thermal regulation and acting as a sensory organ for touch and temperature. The three layers of tissue that comprise the skin are the outer epidermis, the dermis, and the inner hypodermis. The barrier function is mainly performed by the epidermis.
The epidermis is maintained by stem cells which reside in the basal layer and where they generate daughter cells that migrate outward toward the surface of the skin. During this process, keratinocytes undergo a series of biochemical and structural changes that form the various layers of the epidermis.
The outer layer of the epidermis is the stratum corneum, consisting of flattened, dead cells called corneocytes. Corneocytes are keratinocytes that have completed their differentiation and have lost their nucleus and cytoplasmic organelles. Corneocytes are composed primarily of insoluble bundles of keratin surrounded by cross-linked proteins and covalently bound lipids. The epidermis and stratus corneum are continuously renewed by cell division and differentiation from lower basal layers of the skin.
Eventually, outer corneocytes are sloughed from the skin surface through desquamation as new cells arrive. Under normal circumstances, the rate of corneocyte loss is balanced by new cell regeneration. This is a continuously ongoing process of self-renewing and exfoliation takes 20-40 days to complete.
Hyperkeratosis is an umbrella term that refers to the thickening of epidermis that occurs when an increase in corneocytes exceeds the rate of cell sloughing. In some instances, this skin thickening is a natural response to pressure, rubbing or irritation of the skin resulting in protective calluses that most often occur on the hands and feet. Calluses are not painful but may be unattractive. While calluses are a normal response to skin irritation, other forms of hyperkeratosis are due to various skin disorders.
Plaque psoriasis is a chronic autoimmune condition that affects millions of individuals. It typically involves the abnormally rapid production of new skin cells. Skin cells build up and form patches of thick, rough, reddened skin and shed silvery-white scales. As the condition can cause pain and itching, scratching can lead to broken skin, bleeding, and infection. The unsightly appearance can affect psychological and social well-being1 and be socially stigmatizing.2
Plantar and Palmar Plaques
Palmoplantar psoriasis is a variant of psoriasis that characteristically affects the skin of the palms and soles.3 As it directly affects daily living activities, this form of psoriasis has a significant negative impact on quality of life.4,5 The exact cause of palmoplantar pustulosis is unknown; however, it appears to be caused by a combination of genetic and environmental factors.
Keratosis pilaris is a common skin condition which appears as tiny bumps or papules on the skin that may look like small pimples. These rough-feeling bumps are actually plugs of dead skin cells that occur most often behind the upper arms and on the front of thighs.6 Patients with keratosis pilaris usually are asymptomatic with complaints limited to cosmetic appearance or mild pruritus; however, some patients find the appearance of the condition psychologically distressing.6,7
Seborrheic dermatitis is a common disorder affecting the face, chest, back, axilla, and groin areas.8 On the scalp, it is commonly known as dandruff.9 The cause is not known with certainty although genetic and environmental factors, and medical comorbidities may be predisposing factors.10 Seborrheic dermatitis is generally benign but may have a negative impact on patient quality of life.11,12
Treatments for Hyperkeratoses
Keratolytic is a term used to describe agents used to remove skin scales, to smooth the skin, and to treat hyperkeratosis. Keratolytics act by dissolving the intercellular substances in the stratum corneum causing the epidermal cells swell, soften, and desquamate, or by softening and solubilizing keratin.
Salicylic acid is beta-hydroxy acid that differs significantly from traditional keratolytics. The structural integrity of epidermal cells depends upon desmosomes. Salicylic acid decreasing corneocyte cohesiveness of the stratum corneum by disrupting the attachment of desmosomes.13-15 As a result, the loss of epidermal cell cohesion leads to exfoliation.16 As it works differently that keratolytics, it is regarded as a desmolytic agent.17
Salicylic acid is the best studied topical agent for treating plaque psoriasis.18 Although it often responds poorly to treatment, salicylic acid was effective in reducing the scaling of psoriatic lesions in one clinical trial.19 It removes scale and allows other topical medications to penetrate psoriasis lesions.20 It is most beneficial for treating very thick or scaly psoriatic plaques.20 There is consensus that salicylic acid is effective as initial and adjunctive treatment for patients with chronic plaque psoriasis.21 One clinical study demonstrated that salicylic acid used as a monotherapy was highly effective, well-tolerated, and acceptable in with scalp psoriasis.22
Topical salicylic acid can be beneficial for treating keratosis pilaris 7 and in one study, the twice-daily application of a salicylic acid cream improved the appearance of keratosis pilaris by 52%.23 Although salicylic acid is not a first-line therapy for palmoplantar psoriasis, it is frequently added to treatment to improve the stability of anthralin and to increase its penetration and efficacy.24
Keralyt® 5 (Salicylic Acid)
Salicylic acid is a well-established topical agent for treating a variety of dermatoses associated with hyperkeratosis, including chronic plaque psoriasis, calluses, and keratosis pilaris. Once considered to be a keratolytic agent, the activity of salicylic acid as a desmolytic agent, because of its ability to disrupt cellular junctions rather than disrupting intercellular keratin filaments. Keralyt® 5 (Salicylic Acid) is available in several elegant forms; gel, cream, and a shampoo for the scalp. Keralyt® 5 (Salicylic Acid) improves the scaling and roughness in hyperkeratotic skin conditions.
- Wu JJ. Contemporary management of moderate to severe plaque psoriasis. Am J Manag Care. 2017;23:S403-416.
- Feldman SR, Malakouti M, Koo JY. Social impact of the burden of psoriasis: effects on patients and practice. Dermatol Online J. 2014;20:13030.
- Farley E, Masrour S, McKey J, Menter A. Palmoplantar psoriasis: a phenotypical and clinical review with introduction of a new quality-of-life assessment tool. J Am Acad Dermatol. 2009;60:1024-1031.
- Pettey AA, Balkrishnan R, Rapp SR, Fleischer AB, Feldman SR. Patients with palmoplantar psoriasis have more physical disability and discomfort than patients with other forms of psoriasis: implications for clinical practice. J Am Acad Dermatol. 2003;49:271-275.
- Chung J, Callis Duffin K, Takeshita J, et al. Palmoplantar psoriasis is associated with greater impairment of health-related quality of life compared with moderate to severe plaque psoriasis. J Am Acad Dermatol. 2014;71:623-632.
- Hwang S, Schwartz RA. Keratosis pilaris: a common follicular hyperkeratosis. Cutis. 2008;82:177-180.
- Maghfour J, Ly S, Haidari W, Taylor SL, Feldman SR. Treatment of keratosis pilaris and its variants: a systematic review. J Dermatolog Treat. 2020;Sep 14: Epub ahead of print.
- Borda LJ, Perper M, Keri JE. Treatment of seborrheic dermatitis: a comprehensive review. J Dermatolog Treat. 2019;30:158-169.
- Janniger CK, Schwartz RA. Seborrheic dermatitis. Am Fam Physician. 1995;52:149-155.
- Johnson BA, Nunley JR. Treatment of seborrheic dermatitis. Am Fam Physician. 2000;61:2703-2710.
- Sampogna F, Linder D, Piaserico S, et al. Quality of life assessment of patients with scalp dermatitis using the Italian version of the Scalpdex. Acta Derm Venereol. 2014;94:411-414.
- Goldenberg G. Optimizing treatment approaches in seborrheic dermatitis. J Clin Aesthet Dermatol. 2013;6:44-49.
- Davies M, Marks R. Studies on the effect of salicylic acid on normal skin. Br J Dermatol. 1976;95:187-192.
- Huber C, Christophers E. “Keratolytic” effect of salicylic acid. Arch Dermatol Res. 1977;257:293-297.
- Lin AN, Nakatsui T. Salicylic acid revisited. Int J Dermatol. 1998;37:335-342.
- Roberts DL, Marshall R, Marks R. Detection of the action of salicylic acid on the normal stratum corneum. Br J Dermatol. 1980;103:191-196.
- Arif T. Salicylic acid as a peeling agent: a comprehensive review. Clin Cosmet Investig Dermatol. 2015;8:455-461.
- Fluhr JW, Cavallotti C, Berardesca E. Emollients, moisturizers and keratolytic agents in psoriasis. Clin Dermatol. 2008;26:380–386.
- Akamine KL, Gustafson CJ, Yentzer BA, et al. A double-blind, randomized clinical trial of 20% alpha/poly hydroxy acid cream to reduce scaling of lesions associated with moderate, chronic plaque psoriasis. J Drugs Dermatol. 2013;12:855-859.
- Lebwohl M. The role of salicylic acid in the treatment of psoriasis. Int J Dermatol. 1999;38:16–24.
- Naldi L, Rzany B. Psoriasis (chronic plaque). BMJ Clin Evid. 2009;2009:1706.
- Kircik L. Salicylic acid 6% in an ammonium lactate emollient foam vehicle in the treatment of mild-to-moderate scalp psoriasis. J Drugs Dermatol. 2011;10:270–273.
- Kootiratrakarn T, Kampirapap K, Chunhasewee C. Epidermal permeability barrier in the treatment of keratosis pilaris. Dermatol Res Pract. 2015;2015:205012.
- Kneczke M, Rahm C, Landersjö L. The influence of salicylic acid on the in vitro release of anthralin from an o/w cream. Acta Pharm Nord. 1990;2:313-318.