Category Archives: Articles

Skin turnover gone rogue!

Skin turnover gone rogue!

*By: Ibrahim Bahabri


 It is quite easy for us to forget about many processes that go on in our bodies to maintain normal homeostasis. One can go as far as claim that we only notice these fine delicate balancing acts when they cease to work properly; for example, you do not notice that your pancreas is constantly releasing insulin and glucagon to maintain a particular blood glucose level, but a type-1 diabetic who is always a single missed insulin dose away from a trip to the ER sure notices! In similar fashion, when you look at the skin of a healthy individual and see a seemingly slowly if ever changing layer of inert covering, you might forget that you are looking at the result of a continuous balancing act starting from the division of stem cells in the Stratum Basale and the controlled denucleation and migration to the Stratum Corneum. This article looks at a disease where the delicate balancing act in the skin is disturbed, and the consequences that ensue.

Pathophysiology:

The clinical manifestations of Psoriasis are attributed to an autoimmune process mediated by T lymphocytes and dendritic cells primarily, this inflammatory cascade causes an increase in the number of stem cells in the epidermis along with an acceleration of the rate of DNA synthesis in these cells; these changes are also accompanied by a shortening of the normal 1-month epidermis turnover cycle to less than 5 days! Leading to excessive uncontrolled growth of irritable skin and accumulation of extra cells as scales.

Clinical forms:

1- Plaque Psoriasis:

  • The most common manifestations of Psoriasis, lesions in this variation are typically symmetrical raised erythematous scaly plaques that appear on the limbs (especially extensor surfaces), trunk and scalp. Scraping off psoriatic scales can demonstrate the Auspitz sign.
  • Lesions can also appear in intertriginous areas (inverse psoriasis), where lesions tend to be less scaly due to the moister nature of these areas.
  • Lesions are not typically pruritic (which helps to differentiate it from eczema).
  • Treatment of limited disease relies mainly on emollients and topical corticosteroids, with more widespread lesions (more than 10% of total body surface area) requiring systemic immunosuppression.
http://psoriasisfreetips.com/plaque-psoriasis-epidemiology/

http://psoriasisfreetips.com/plaque-psoriasis-epidemiology/

http://dermatologyoasis.net/category/psoriasis/page/4/

http://dermatologyoasis.net/category/psoriasis/page/4/

 

 

 

 

 

 

 

 

2- Guttate (Eruptive) Psoriasis:

  • Can appear along with plaque psoriasis or independently. It can be triggered by infections such as strep throat.
  • Characterized by numerous (possibly pruritic) scaly red papules.
  • Treatment mainstay is phototherapy and topical steroids, with adding antibiotics to the regimen being an area of controversy. Phototherapy and sun exposure can also be used in treatment.
http://www.pcds.org.uk/clinical-guidance/guttate-psoriasis

http://www.pcds.org.uk/clinical-guidance/guttate-psoriasis

3- Pustular Psoriasis:

One of the more dangerous forms of psoriasis, characterized by a breakout of scaly erythema and pustules that can be triggered by withdrawal of oral immunosuppressive therapy.

http://psoriasisfreetips.com/psoriasis-photos/pustular-psoriasis-photos/

http://psoriasisfreetips.com/psoriasis-photos/pustular-psoriasis-photos/

4- Nail Psoriasis:

Psoriasis can often induce nail pitting and onycholysis that typically develop after the appearance of the primary skin disease, and considering the association of nail involvement of nail pitting with other Seronegative Spondyloarthropathies (such as Ankylosing Spondylitis), the presence of nail pitting can be a clue pointing to concomitant or impending psoriatic arthritis.

http://www.sterishoe.com/foot-care-blog/toenail-fungus/is-it-psoriasis-eczema-or-toenail-fungus/

http://www.sterishoe.com/foot-care-blog/toenail-fungus/is-it-psoriasis-eczema-or-toenail-fungus/

https://psoriasislab.com/nail-psoriasis/

https://psoriasislab.com/nail-psoriasis/

 

 

 

 

 

 

 

 


*Medical Intern

King Saud University

Riyadh, Saudi Arabia

 

References:

1- https://www.uptodate.com/contents/epidemiology-clinical-manifestations-and-diagnosis-of-psoriasis?search=psoriasis&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2#H14

2- https://www.uptodate.com/contents/treatment-of-psoriasis-in-adults?search=psoriasis&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

3- https://emedicine.medscape.com/article/1943419-overview

The Hair Growth Cycle

The Hair Growth Cycle

*By: Ghadah Alhammad


 Hair shedding is a natural part of the hair growth cycle. We lose hair so that newer hair can replace it. Human hair grows in a life-long cyclic transformation which consists of three primary phases; anagen, catagen and telogen. Throughout the cycle, each hair follicle is independent and goes through the cycle at different times of growth and shedding.

(Photo source: http://dermaluxemedispa.com)

Anagen

The hair growth cycle begins with the anagen or growth phase. During this phase cells in the root of the hair divide rapidly to add to the hair shaft. Hair grows about 1 cm a month. This phase can vary widely in duration based on different factors like age, sex, hormonal status, and genetics. Some people have difficulty growing their hair past a certain length because they have a short anagen phase. On the other hand, people with very long hair and those who are recorded in Guinness World Records with a very long hair usually have a longer anagen phase. About 80% of hairs will be in this phase and it can last anywhere from 2-6 years.

Catagen

At the end of the anagen phase, the hair enters the catagen phase, it is a short transitional stage where the hair is no longer growing. About 2-5% of all hairs are in this phase at any given moment. During this stage, a “club hair” is formed which occurs when the outer root sheath shrinks and attaches to the root of the hair. This club hair isn’t attached to a blood supply and cannot grow any longer. This phase lasts usually for about two to three weeks.

Telogen

Lastly, the hair enters the telogen phase, it is the final resting phase and usually accounts for 15% of all hairs at any given time. This phase lasts for about 2-3 months. During this phase, the hair follicle is completely at rest and the club hair is completely formed. The hair begins to shed at normal levels and the old hair is rested. Simultaneously, a new hair begins the anagen phase and the whole cycle is repeated again.


*Medical Student
King Saud University
Riyadh, Saudi Arabia

References:

  1. https://www.webmd.com/skin-problems-and-treatments/hair-loss/science-hair#1
  2. https://emedicine.medscape.com/article/835470-overview#a1
  3. Fitzpatrick Color Atlas And Synopsis Of Clinical Dermatology, Seventh edition

Skin Whitening Agents

Skin whitening agents

*by Lama Alkahtani 


Skin lightening products work by blocking the undesired pigment formation, during the pigmentation process. The pigment melanin is produced in melanosomes by melanocytes in a complex process called melanogenesis. During melanogenesis tyrosine forms melanin which then forms two types of melanin pigments one exerting a red colour (pheomelanin) and the other exerting a black colour (Eumelanin) , this pathway is controlled by the enzymatic action of tyrosinase. Below is a list of skin lightening drugs that work on different steps in the pathway.

1-Before the synthesis of melanin through the transcription process 

Tretinoin

2-During melanin synthesis

Inhibition of tyrosinase, preventing the conversion of tyrosine to melanin

  • Hydroquinone
  • 4-Hydroxyanisole
  • kojic acid

Peroxidase inhibition:

  • Phenols

3-After melanin synthesis

Skin turnover acceleration:

  • Glycolic acid
  • Lactic acid
  • Retinoic acid

Inhibition of melanosome transfer:

  • Soybean/milk extracts
  • Niacinamide

Tyrosinase degradation:

  • Linoleic acid
  • α-Linolenic acid

* Medical student 

King Saud University 

Riyadh, Saudi Arabia 

References

1- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769151/

2- https://www.ncbi.nlm.nih.gov/pubmed/21265866

3- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3699939/