MRCP Dermatology: Mastering Common Skin Condition Guidelines

As an examiner and long-time educator in the medical field, I've observed that while core medicine topics often take center stage in MRCP preparation, dermatology can sometimes be overlooked. However, a solid understanding of common dermatological conditions and their management guidelines is absolutely crucial for success in both MRCP Part 1 and Part 2 (PACES). Dermatology questions frequently appear, and knowing the latest guidelines can make the difference in complex scenarios.

This post will guide you through the essential guidelines for some high-yield dermatological conditions commonly tested in the MRCP exam. We’ll focus on practical, guideline-based approaches that you can apply directly.

1. Atopic Eczema (Atopic Dermatitis)

Atopic eczema is a chronic, relapsing inflammatory skin condition, highly prevalent. Understanding its management is key.

Diagnosis:

• Clinical: Characterized by pruritus, typical morphology (flexural distribution in adults), and chronic relapsing course. Associated features like a personal or family history of atopy (asthma, allergic rhinitis, eczema) are supportive.

Severity Assessment:

• Mild, Moderate, Severe classifications guide management. Tools like Eczema Area and Severity Index (EASI) are used in clinical practice and trials, but for MRCP, a pragmatic assessment based on extent, impact on quality of life, and control is often sufficient.

Management Guidelines:

1. Emollients: The cornerstone of treatment. Advise liberal and frequent application (several times a day) even when the skin is clear. They restore skin barrier function.

2. Topical Corticosteroids (TCS): Applied to inflamed areas. Potency is chosen based on severity, site, and age (e.g., mild for face/flexures, moderate/potent for trunk/limbs). Counsel patients on appropriate use to avoid side effects (e.g., skin atrophy).

3. Topical Calcineurin Inhibitors (TCIs - Tacrolimus, Pimecrolimus): Used for facial/flexural eczema or if TCS are poorly tolerated/ineffective. Can be used proactively twice weekly on previously affected areas.

4. Managing Flares: Increase emollient and TCS application. Consider wet wraps for severe flares.

5. Infection: Recognise signs of bacterial (Staphylococcus aureus, impetiginisation) or viral (eczema herpeticum) infection. Swabs for culture & sensitivity are important for bacterial infections, followed by appropriate antibiotics. Aciclovir for eczema herpeticum.

6. Systemic Therapy: Reserved for severe, refractory eczema impacting quality of life. Options include oral corticosteroids (short courses for severe flares), ciclosporin, methotrexate, azathioprine, and increasingly, biologics (e.g., dupilumab) and JAK inhibitors, often initiated by specialists.

7. Patient Education: Crucial for adherence, trigger avoidance, and self-management plans.

2. Psoriasis

Psoriasis is a chronic inflammatory skin condition characterized by well-demarcated erythematous plaques with silvery scales. It's not just a skin disease; it's a systemic inflammatory disorder.

Diagnosis:

• Clinical: Typical lesions are symmetrically distributed, commonly on extensor surfaces (elbows, knees, scalp, lower back). Nail changes (pitting, onycholysis, oil spots) are common. Guttate psoriasis often follows a strep throat infection.

Severity Assessment:

• Based on Body Surface Area (BSA) affected, Psoriasis Area and Severity Index (PASI), and impact on quality of life (DLQI).

  • Mild: <3% BSA

  • Moderate: 3-10% BSA

  • Severe: >10% BSA or involvement of critical sites (face, palms, soles, genitals) or significant impact on quality of life.

Management Guidelines:

1. Topical Therapy: First-line for mild-moderate psoriasis.

   • Corticosteroids: Potent/super-potent TCS are primary (e.g., betamethasone dipropionate).

   • Vitamin D analogues (Calcipotriol, Calcitriol): Often used in combination with TCS for enhanced efficacy and to reduce TCS side effects.

   • Coal Tar: Effective, but less cosmetically appealing.

   • Dithranol: Potent, but can stain skin/clothes.

   • Salicylic Acid: Useful for thick plaques to aid penetration of other topicals.

2. Phototherapy: For moderate-to-severe psoriasis not responding to topical agents (e.g., narrow-band UVB, PUVA).

3. Systemic Therapy: For severe psoriasis or widespread disease affecting quality of life, often managed by dermatologists.

   • Conventional: Methotrexate, Ciclosporin, Acitretin. Requires careful monitoring for side effects (e.g., liver toxicity with methotrexate, renal toxicity with ciclosporin).

   • Biologics: Anti-TNF-α (e.g., adalimumab, etanercept, infliximab), IL-12/23 inhibitors (ustekinumab), IL-17 inhibitors (secukinumab, ixekizumab), IL-23 inhibitors (guselkumab). Highly effective but associated with infection risk and requiring specialist initiation/monitoring.

4. Psoriatic Arthritis: Screen all psoriasis patients for joint symptoms. Referral to rheumatology is essential.

5. Comorbidities: Psoriasis is associated with metabolic syndrome, cardiovascular disease, and psychological distress. Holistic management is crucial.

3. Urticaria (Hives)

Urticaria is characterized by transient, itchy wheals (hives) that typically resolve within 24 hours. Angioedema can occur with or without wheals.

Classification:

• Acute Urticaria: Lasts less than 6 weeks.

• Chronic Urticaria: Lasts more than 6 weeks, with daily or almost daily occurrence. Further divided into Chronic Spontaneous Urticaria (CSU, no identifiable trigger) and Chronic Inducible Urticaria (CIndU, specific triggers like cold, pressure, heat).

Diagnosis & Investigations:

• History: Crucial for identifying triggers (foods, drugs, infections, physical stimuli, stress).

• Acute: Usually self-limiting. Limited investigations unless specific triggers are suspected (e.g., food allergy).

• Chronic: Focus on excluding underlying causes (e.g., autoimmune conditions, chronic infections). Basic investigations might include FBC, ESR/CRP, LFTs, TFTs, ANAs, but extensive screening is often unhelpful unless indicated by history.

Management Guidelines:

1. Antihistamines: Non-sedating H1-antihistamines (e.g., loratadine, fexofenadine, cetirizine) are first-line. For chronic urticaria, up-dosing (up to four times the standard dose) is recommended if standard doses are ineffective.

2. Systemic Corticosteroids: Short courses can be used for severe acute flares or angioedema. Long-term use is discouraged due to side effects.

3. Omalizumab (Anti-IgE monoclonal antibody): For chronic spontaneous urticaria refractory to high-dose antihistamines. Initiated by specialists.

4. Ciclosporin: An alternative for severe chronic urticaria unresponsive to antihistamines and omalizumab.

5. Trigger Avoidance: If a clear trigger is identified (e.g., NSAIDs, specific foods in acute cases).

General Tips for MRCP Dermatology Questions:

• Look for Clues: Pay attention to location (flexural, extensor), morphology (vesicles, bullae, scales, plaques), associated features (itching, pain, systemic symptoms), and patient history (atopy, drug exposure, travel).

• Systemic Associations: Remember that many skin conditions have systemic associations (e.g., psoriasis with psoriatic arthritis/metabolic syndrome, dermatitis herpetiformis with coeliac disease, erythema nodosum with various systemic causes).

• Emergency Recognition: Be able to identify dermatological emergencies like Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN), severe drug reactions (DRESS syndrome), and eczema herpeticum, and know the immediate management principles.

• Drug-Induced Rashes: A common MRCP topic. Differentiate between common drug eruptions (e.g., maculopapular rash) and more severe reactions.

By systematically approaching dermatological cases with these guideline-focused principles, you'll not only enhance your clinical acumen but also significantly boost your performance in the MRCP exam. Good luck! Keep practicing and reviewing those guidelines.