1. Introduction Skin diseases are one of the most common presentations in general practice, ranging from benign to life-threatening conditions . Australia has a high burden of skin diseases , particularly skin cancers due to high UV exposure . This document provides a structured approach for diagnosing, differentiating, and managing skin lesions in primary care.
2. Diagnosis of Skin Lesions 2.1 History
Onset & duration : Acute (e.g., herpes zoster, cellulitis) vs. chronic (e.g., psoriasis, eczema).Symptoms : Itch (eczema, scabies), pain (shingles, cellulitis), bleeding (BCC, SCC).Evolution : Changing size, shape, or color (suspicious for malignancy).Exposure history : Sun exposure, chemicals, allergens, infections.Personal & family history : Skin cancers, atopy (eczema, asthma, hay fever).
2.2 Clinical Examination
Site distribution : Face (BCC), scalp (SCC), flexures (eczema, intertrigo).Lesion characteristics :
Shape : Nodular (BCC), scaly (SCC, psoriasis).Color : Uniform (benign) vs. varied (melanoma).Borders : Well-defined (benign) vs. irregular (malignant).Surface changes : Scaling (psoriasis, actinic keratosis), ulceration (SCC).
2.3 Diagnostic Tools
Dermatoscopy : Essential for evaluating pigmented lesions.Skin biopsy :
Punch biopsy : Inflammatory dermatoses (psoriasis, eczema).Excisional biopsy : Suspected melanoma.
Wood’s lamp : Fungal infections (tinea), erythrasma.
3. Differential Diagnosis 3.1 Benign Lesions Condition Features Seborrheic Keratosis “Stuck-on” appearance, rough surface. Skin Tags Soft, pedunculated lesions in skin folds. Cherry Angioma Small, red papules, common with aging. Lipoma Soft, mobile subcutaneous nodule.
3.2 Precancerous Lesions Condition Features Management Actinic Keratosis Rough, scaly, sun-exposed areas. Cryotherapy, 5-FU, PDT. Bowen’s Disease (SCC in situ) Red, scaly plaque, slow-growing. Excision, imiquimod.
3.3 Malignant Lesions Condition Features Management Basal Cell Carcinoma (BCC) Pearly, telangiectatic nodule, slow-growing. Excision, Mohs surgery. Squamous Cell Carcinoma (SCC) Scaly, ulcerated lesion, sun-exposed areas. Wide excision, radiotherapy. Melanoma Asymmetry, border irregularity, color variation, diameter >6mm, evolving. Wide excision, sentinel node biopsy.
3.4 Inflammatory Skin Conditions Condition Features Management Psoriasis Erythematous plaques with silvery scales. Topical steroids, phototherapy, biologics. Eczema (Atopic Dermatitis) Itchy, dry, inflamed skin, flexural areas. Emollients, steroids, antihistamines. Contact Dermatitis Localized, itchy rash after allergen exposure. Patch testing, avoidance, steroids.
3.5 Infective Skin Conditions Condition Pathogen Features Treatment Impetigo (School Sores) S. aureus , S. pyogenes Honey-crusted lesions. Topical mupirocin, oral flucloxacillin. Cellulitis S. aureus , S. pyogenes Warm, swollen, tender skin. Oral flucloxacillin, IV in severe cases. Scabies Sarcoptes scabiei Intense itch, burrows in web spaces. Permethrin cream, oral ivermectin. Herpes Zoster (Shingles) Varicella-zoster virus Painful dermatomal rash. Valaciclovir, pain management.
4. Management of Skin Conditions 4.1 Benign Lesions
Observation (if asymptomatic).Cryotherapy (for symptomatic seborrheic keratosis).Excision (cosmetic or irritation reasons).
Standard excision biopsy margin is 2mm
4.2 Precancerous Lesions
Actinic Keratosis :
Cryotherapy (single lesion).
Topical 5-FU or imiquimod (multiple lesions).
Photodynamic therapy (PDT).
Bowen’s Disease :
Excision (high-risk sites).Topical therapy for superficial cases.
4.3 Malignant Lesions
BCC : Excision (2-3mm margins), Mohs for cosmetically sensitive areas.SCC : Wide excision (4–6mm margins), sentinel lymph node biopsy for high-risk cases.Melanoma :
Wide local excision (1–2cm margins) unless melanoma in situ (5mm margin)Sentinel node biopsy if >1mm thickness.Immunotherapy for metastatic cases .
4.4 Inflammatory & Infective Conditions
Eczema : Emollients, topical steroids, avoiding triggers.Psoriasis : Topical steroids, vitamin D analogs, phototherapy , systemic agents (methotrexate, biologics).Scabies : Treat patient + contacts, permethrin or ivermectin .Cellulitis : Oral flucloxacillin , IV if severe.
5. Prevention & Monitoring
Regular Skin Checks :
High-risk patients: 6-12 monthly dermatologist review.
General population: 2-yearly skin checks .
Sun Protection :
SPF 50+ sunscreen, broad-brimmed hats , avoiding peak sun exposure.
Patient Education :
ABCDE rule for melanoma.Self-monitoring of skin lesions .
6. Referral Guidelines
Urgent referral :
Suspicious pigmented lesions (rule out melanoma).Aggressive SCC/BCC (near eyes, nose, ears).
Non-urgent referral :
Complex inflammatory dermatoses (unresponsive psoriasis, eczema).Uncertain diagnosis requiring biopsy .
7. Conclusion Skin diseases are highly prevalent in Australian general practice , requiring early detection, accurate diagnosis, and effective management . A structured approach, dermatoscopy, biopsies, and adherence to RACGP guidelines improve patient outcomes.
