DERMATOLOGY: PSORIASIS, SCABIES, AND ECZEMA: A TEACHER’S COMPREHENSIVE GUIDE
Welcome, future pharmacists and healthcare professionals!
Skin conditions with a wide range of symptoms, including eczema and acne, are referred to as dermatological disorders. They may be painless or painful, transient or permanent, and may pose a threat to life. Certain skin disorders can be inherited, while others have situational causes. Though the majority of skin disorders are benign, some may be signs of a more serious problem. As a pharmacy educator with years of experience teaching pharmacotherapeutics, I have observed that students often find dermatological disorders challenging due to the variety of conditions and their complex pathophysiology. Let me tell you: Understanding dermatological disorders is essential for every pharmacy professional.
In this comprehensive guide, I will walk you through the major dermatological disorders—Psoriasis, Scabies, and Eczema. I will explain their types, etiology, pathogenesis, clinical manifestations, and both non-pharmacological and pharmacological management. By the end of this article, you will have a thorough understanding of these critical conditions. Let us begin our journey!
Dpharmguru’s exam insights:
Dermatological disorders are frequently tested in pharmacy exams. Remember: Psoriasis is a chronic autoimmune condition with rapid skin cell turnover. Scabies is caused by the Sarcoptes scabiei mite. Eczema is an inflammatory skin condition with dry, itchy skin. Pay special attention to the types of each disorder and their pharmacological management—these are almost always asked in exams!
1. PSORIASIS
Psoriasis is a chronic autoimmune condition in which skin cells build up rapidly, causing thick, pink or red skin patches covered with white or silvery scales, called plaques. The rash can develop anywhere on the body. Mostly, it covers only a few patches of skin; however, in severe cases, the plaques join and cover a large area of the body.
Types of Psoriasis
- Plaque Psoriasis: Most common type. Causes red, inflamed patches on light skin tones and purple or grayish-coloured patches on dark skin tones. Covered with whitish-silver scales or plaques. Develops on elbows, knees, and scalp.
- Inverse Psoriasis: Appears in skin folds like thin pink plaques with no scales.
- Guttate Psoriasis: Appears as small, red, drop-shaped scaly spots that develop after a sore throat caused by streptococcal infection in children and young adults.
- Pustular Psoriasis: Appears as small, pus-filled bumps on top of red patches or plaques.
- Sebopsoriasis: A cross between psoriasis and seborrheic dermatitis. Appears as red bumps and plaques with greasy yellow scales on the face and scalp.
- Erythrodermic Psoriasis: A severe and rare type. Skin appears sunburned and scales often slough off in large sections or sheets. Covers almost the entire body.
Etiology of Psoriasis
Psoriasis is an immune system disorder in which the immune system overreacts, causing inflammation and leading to rapid growth of new skin cells. It is genetic and may be passed down to children from their parents.
Common Triggers:
- Skin injury (cuts, scrapes, or surgery)
- Emotional stress
- Streptococcal or other infections affecting the immune system
- Certain prescribed medications (lithium and beta-blockers)
- Cold weather, less exposure to sunlight and humidity, and more exposure to hot, dry indoor air
Pathogenesis of Psoriasis
- Interaction with environmental factors
- Hyperactivity of T-cells
- Epidermal infiltration and keratinocyte proliferation
- Deregulated inflammatory response
- Large production of various cytokines
- Superficial blood vessels dilate and vascular engorgement occurs
- Epidermal hyperplasia and improper cell maturation
- Failure to release adequate lipids, which leads to flaking and scaling presentation
- Silvery scales on the skin
Clinical Manifestations of Psoriasis
- Raised, swollen patches of skin that appear red on light skin tones and brown or purple on dark skin tones
- Whitish-silver scales or plaques on red patches or gray scales on purple and brown patches
- Soreness, itching, and burning sensations around patches
- Cracked and bleeding dry skin
- Thick and pitted nails
- Painful and inflamed joints
Non-Pharmacological Management of Psoriasis
- The patient should use emollients frequently during therapy-free periods to reduce skin dryness
- He/she should apply emollients about 4 times a day to achieve a beneficial effect
Pharmacological Management of Psoriasis
- Steroid creams should be applied to the affected areas
- Moisturisers should be used for dry skin
- Anthralin should be used to slow down the production of skin cells
- Medicated lotions, shampoos, and bath solutions should be used to improve scalp psoriasis
- Vitamin D3 ointment should be applied
- Vitamin A or retinoid creams should be applied
- UV light at specific wavelengths should be used to decrease skin inflammation
- PUVA combined with psoralen with exposure to UV light should be used
- Methotrexate should be prescribed in severe cases
- Cyclosporine should be prescribed in severe cases
- Newer immunotherapy medications may be used that block the body’s immune system
Dpharmguru’s exam insights:
Psoriasis management is frequently tested. Remember: Topical treatments include corticosteroids, Vitamin D3 analogues, and retinoids. Systemic treatments for severe psoriasis include Methotrexate, Cyclosporine, and biologics (TNF inhibitors). A common exam question is: “What is the first-line topical treatment for psoriasis?” (Answer: Topical corticosteroids).
2. SCABIES
Scabies is a skin condition caused by the Sarcoptes scabiei var. hominis mite. These are tiny bugs that make tunnels beneath the skin and cause small red bumps and severe itching.
Common Sites of Infestation:
- Folds between the fingers and toes
- Folds in the thighs and genital area
- Bends at the wrists and knees
- Area around the waist
- Under the fingernails
- Under rings, watch bands, and bracelets
- Area around the nipples
Types of Scabies
- Crusted (Norwegian) Scabies: Forms crusted areas that cover a large skin area. Occurs in people with a compromised immune system who might acquire millions of mites.
- Nodular Scabies: Forms brown-red nodules, which persist even when the mites have gone. Occurs more commonly in children.
- Bullous Scabies: Forms skin blisters and occurs in adults.
- Scalp Scabies: Forms psoriasis-like scales on the scalp.
Etiology of Scabies
Scabies in humans is caused by an obligate human parasite, Sarcoptes scabiei var. hominis (host-specific mite).
Pathogenesis of Scabies
Scabies spreads easily from one person to another who lives in close contact. If a family member has scabies, the healthcare provider should check and treat other family members and close relatives too. The transmission occurs through:
- Direct skin-to-skin contact with an infected person
- Sharing clothing, bedding, or towels with an infected person
- The female mite burrows into the skin and lays eggs
- The eggs hatch and the mites spread to other areas of the skin
Clinical Manifestations of Scabies
- Intense itching that worsens at night, making it hard for the patient to sleep
- Itchy bumps that become infected due to scratching
- A grayish or skin-colored rash appears on the skin in later stages
- Scabies in children causes itching all over the body, making them bad-tempered or tired due to lack of sleep
Non-Pharmacological Management of Scabies
- The patient should soak his/her skin in cool water or take an oatmeal bath
- Apply a cool, wet washcloth to the irritated skin areas to relieve itching
- Apply calamine lotion to relieve pain and itching of minor skin irritations
- Take prescribed OTC antihistamines to relieve allergic symptoms caused by scabies
Pharmacological Management of Scabies
Topical creams and lotions should be applied from the neck down to the soles of the feet and left on the skin for about 8–10 hours.
- Topical creams and lotions: Permethrin cream, Malathion lotion
- Anti-parasitic medications: Prescribed to patients with crusted scabies, poor immune systems, or those not responding to topical medications
- Antihistamines: Loratadine, Cetirizine—to relieve itching
Dpharmguru’s exam insights:
Scabies management is frequently tested. Remember: Permethrin cream is the first-line treatment for scabies. It should be applied from the neck down and left on for 8-10 hours. All close contacts should be treated simultaneously. A common exam question is: “What is the first-line treatment for scabies?” (Answer: Permethrin cream).
3. ECZEMA
The term eczema has been derived from the Greek word ekzein, meaning to boil over or break out. Eczema is a condition in which the skin becomes dry, red, itchy, and bumpy. It is a type of dermatitis that hampers the function of the skin barrier, thus making the skin more sensitive and vulnerable to infection and dryness.
Types of Eczema
- Atopic Dermatitis: Causes dry, itchy skin that appears with a red rash.
- Contact Dermatitis: Caused by exposure to an allergen that irritates the skin or triggers an allergic reaction.
- Dyshidrotic Dermatitis: Occurs more commonly in women. Causes itchy, scaly patches of skin on fingers, palms of hands, and soles of feet.
- Nummular Dermatitis: Round, red, and severely itchy scaly patches on the lower legs, due to a break in the skin and very dry skin.
- Stasis Dermatitis: Occurs on the lower legs due to poor blood flow.
Etiology of Eczema
The cause of eczema is not completely known; however, researchers believe it to be triggered by an overactive immune system. Eczema occurs when the skin is exposed to external irritants:
- Chemicals or preservatives in cleansers and detergents
- Scented products
- Cigarette smoke
- External allergens (pollens, mold, dust, or dust mites)
- Rough, scratchy material (wool)
- Synthetic fabrics
- Sweating
- Changes in temperature
- Stress
- Food allergies
- Upper respiratory infections
Pathogenesis of Eczema
Genes related to atopic dermatitis encode epidermal and immunologic proteins. Loss-of-function mutation in the gene encoding for filaggrin protein is a major influencing factor for atopic dermatitis. Filaggrin is a component of the cornified cell envelope, produced by differentiating keratinocytes, that is essential for building the natural moisturising factor.
Pathogenesis Pathway:
- Any etiological/genetic factor (allergen)
- Activation of immune cells
- Release of T-cells
- Stimulation of cytokine release
- Inflammation
- Eczema (inflammation, dry, reddened, and itching skin)
Clinical Manifestations of Eczema
- Dry and itchy skin
- Red rashes
- Bumps on the skin
- Scaly, leathery patches of skin
- Crusting skin
- Swelling
Non-Pharmacological Management of Eczema
- Bathing: Moisturizers should be applied soon after bathing
- Wet dressing: Application of wet bandages over lesions covered by corticosteroids
- Light therapy (Phototherapy): Controlled exposure to natural sunlight under medical supervision
- Counseling: Helps people with eczema deal with frustration
- Relaxation, behavior modification, and biofeedback: Assist with habitual scratching
Pharmacological Management of Eczema
- A psychiatrist should be consulted for medication and a therapist for counseling if the patient has poor mental or emotional status
- Skin should be moisturized by applying cream or ointment several times a day (after bathing)
- Skin products containing ceramide should be used
- Cortisone creams and ointments (OTC steroid found in hydrocortisone and hydrocortisone acetate) should be applied to control itching and redness
- OTC antihistamines (cetirizine, diphenhydramine, fexofenadine, and loratadine) should be taken to relieve severe itching
- Wet dressings should be applied in hospitals over the lesions covered by corticosteroids
Dpharmguru’s exam insights:
Eczema management is frequently tested. Remember: Moisturizers and topical corticosteroids are the mainstay of treatment. Emollients should be applied multiple times daily. Antihistamines help control itching. A common exam question is: “What is the first-line treatment for eczema?” (Answer: Topical corticosteroids).
COMPARISON: PSORIASIS VS ECZEMA
| Feature | Psoriasis | Eczema |
|---|---|---|
| Pathophysiology | Autoimmune, rapid skin cell turnover | Inflammatory, skin barrier dysfunction |
| Lesion Appearance | Well-defined, thick silvery scales | Poorly defined, red, dry, itchy patches |
| Common Sites | Elbows, knees, scalp | Flexures (elbows, knees), face, neck |
| Itching | Mild to moderate | Severe |
| Nail Involvement | Yes (pitting, thickening) | No |
| Treatment | Topical steroids, Vitamin D analogues, Methotrexate, Biologics | Emollients, Topical steroids, Antihistamines |
FREQUENTLY ASKED QUESTIONS (FAQs)
1. What is the difference between psoriasis and eczema?
Psoriasis is an autoimmune condition with rapid skin cell turnover, causing thick, silvery scales. Eczema is an inflammatory condition with skin barrier dysfunction, causing dry, itchy, red patches.
2. What is the first-line treatment for psoriasis?
First-line treatment for mild to moderate psoriasis is topical corticosteroids. Other options include Vitamin D analogues, retinoids, and phototherapy.
3. What is the first-line treatment for scabies?
The first-line treatment for scabies is Permethrin cream applied from the neck down and left on for 8-10 hours.
4. What is the difference between atopic dermatitis and contact dermatitis?
Atopic dermatitis is a chronic, genetic condition with dry, itchy skin. Contact dermatitis is caused by exposure to an allergen or irritant that triggers a reaction.
5. What is the role of filaggrin in eczema?
Filaggrin is a protein essential for building the natural moisturising factor of the skin. Loss-of-function mutations in the filaggrin gene are a major risk factor for atopic dermatitis (eczema).
6. What is crusted (Norwegian) scabies?
Crusted (Norwegian) scabies is a severe form of scabies that forms crusted areas covering a large skin area. It occurs in people with a compromised immune system who might acquire millions of mites.
SUMMARY
Dermatological disorders are among the most common conditions affecting people worldwide. This guide covered the major dermatological disorders:
- Psoriasis: Chronic autoimmune condition with rapid skin cell turnover. Managed with topical corticosteroids, Vitamin D analogues, systemic agents (Methotrexate, Cyclosporine), and biologics.
- Scabies: Parasitic infestation caused by Sarcoptes scabiei mite. Managed with Permethrin cream and antihistamines.
- Eczema: Inflammatory skin condition with skin barrier dysfunction. Managed with emollients, topical corticosteroids, and antihistamines.
As I always tell my students: “Dermatological disorders affect not only the skin but also the psychological well-being of patients. Understanding their pathophysiology and pharmacology is essential for improving patient outcomes and quality of life.”
REFERENCES AND FURTHER READING
- Pharmacy Council of India (PCI). (2022). Pharmacotherapeutics Syllabus. New Delhi: PCI.
- Rang, H. P., & Dale, M. M. (2021). Rang & Dale’s Pharmacology (9th ed.). Elsevier.
- Goodman, L. S., & Gilman, A. (2018). Goodman & Gilman’s The Pharmacological Basis of Therapeutics (13th ed.). McGraw-Hill.
- Katzung, B. G. (2021). Basic and Clinical Pharmacology (15th ed.). McGraw-Hill.
- National Psoriasis Foundation. (2023). Psoriasis Treatment Guidelines.
- American Academy of Dermatology. (2023). Eczema and Scabies Treatment Guidelines.
Disclaimer: This article is for educational purposes only and does not constitute medical advice. Always consult qualified healthcare professionals for medical concerns. Pharmaceutical regulations and guidelines may vary by region—always refer to your local regulatory authorities for specific requirements.
written by:
Dr. N. Sujith Kumar
For More Study Materials, Visit: www.dpharmguru.com
