Skin Disorders/Rash

CFPC Key Features

Skin Disorders

  1. In dealing with a persistent skin problem that is not responding to treatment as expected:

    1. Reconsider the diagnosis (e.g., “eczema” may really be a fungal infection).

    2. Investigate or modify treatment (e.g., for acne).

  2. In a patient presenting with a skin lesion, distinguish benign from serious pathology (e.g., melanoma, pemphigus, cutaneous T-cell lymphoma) by physical examination and appropriate investigations (e.g., biopsy or excision).

  3. In a patient presenting with a cutaneous manifestation of a systemic disease or condition (e.g., Wegener’s granulomatosis, lupus, a drug reaction), consider the diagnosis of systemic disease and confirm it through history, physical examination, and appropriate investigations.

  4. When prompted by a patient with a concern about a localized skin lesion or when screening for mucocutaneous lesions, inspect all areas of the skin (e.g., nails, scalp, oral cavity, perineum, soles of the feet, back of the neck).

  5. Diagnose and promptly treat suspected life-threatening dermatologic emergencies (e.g., Stevens-Johnson syndrome, invasive cellulitis, chemical or non-chemical burns).

  6. In high-risk patients (diabetics, bed or chair bound, peripheral vascular disease):

    1. Examine the skin even when no specific skin complaint is present.

    2. Treat apparently minor skin lesions aggressively.

  7. In a patient being treated for a new or persistent skin condition (e.g., acne, psoriasis), determine the impact on the patient’s personal and social life.


  1. In a patient with a new rash:

    1. Take a focused history and do an appropriate skin examination

    2. If the diagnosis remains unclear obtain a more detailed history and examination, including the entire mucocutaneous system and other body systems as indicated

  2. When assessing a patient with a rash look for and recognize common patterns to aid diagnosis.

  3. Use appropriate terminology with respect to lesion type, shape, arrangement, and distribution to facilitate communication and documentation

  4. In an unwell patient presenting with a rash:

    • Identify potential life-threatening systemic conditions (e.g., meningococcal septicemia, necrotizing fasciitis, toxic shock, Stevens-Johnson syndrome)

    • Initiate treatment and/or urgent/emergent referral

  1. In a patient with a persisting undiagnosed rash:

    • Consider a systemic disorder (e.g., systemic lupus erythematosus, diabetes, celiac)

    • Investigate appropriately (e.g., scraping, culture, biopsy, lab work)

    • Pursue further investigations and/or refer as indicated regardless of negative results

  1. In all patients with a persistent or recurrent rash explore the functional and emotional aspects of that disorder, recognizing that what looks like a minor condition may have a profound impact.

  2. In a patient with a persistent or recurrent rash explore issues of:

    • Exposure to skin irritants or allergens

    • Adherence to the treatment plan

    • Use of confounding medications and treatments (e.g., topical anesthetics, topical steroids, home remedies)

  1. In a patient with an infectious rash:

    • Manage contagion risk

    • Ensure that public health bodies are informed when indicated

See Acne, Psoriasis, Fungal Disease, Urticaria/Angioedema, Cellulitis.

General Overview

  • Inspect all areas of skin

    • Include scalp, behind ears, back of neck

    • Oral cavity

    • Genital and perineum

    • Nails, palms of hands and soles of feet

    • Intertriginous areas (e.g., axilla, skin folds of the breasts and between digits)

  • Biopsy or excision to rule out serious pathology


  • Previous episodes

  • Previous treatment

  • Contact/exposure/travel (e.g., infectious, new detergents/fabric softeners/lotions/deodorants, metal belt buckles/glasses, different humidity/climates)

  • Medication/drugs (e.g., antibiotics [penicillin, sulfonamides], corticosteroids, NSAIDs, anti-epileptics)

  • PMH/family history

  • Associated symptoms (pain, pruritus, bleeding, exudate, blistering/ulcerations, fever, aches)

  • Occupational history

  • Impact on patient's life (function, sleep, mood, social life)

Physical Exam


  • Size/shape/texture: well vs. poorly demarcated, targetoid, verrucous, umbilicated

  • Colour: erythematous, violaceous, hyper/hypopigmented, depigmented, jaundiced

  • Arrangement: solitary, grouped, linear, reticular/mottled, dermatomal

  • Lesion type (primary/secondary):

    • Primary (< 1cm/>1cm) = macule/patch, papule/plaque, nodule/tumour, vesicle/bulla

    • Secondary = lichenification, maceration, erosion/ulceration

  • Distribution

  • Always look at nails (e.g, pitting, oil spots), hair (e.g., scalp plaques, hair thinning), mucous membranes (e.g., white lacy patches, open sores), intertriginous areas

General Skin Care

  • Eliminate exacerbating factors

    • Excessive bathing (without subsequent moisturization)

    • Low humidity environment

    • Overheating/hot water exposure

    • Avoid potential allergens and irritants

      • Exposure to solvents/detergents

      • Avoid fragrant/perfumed topic agent

      • Avoid coarse fiber clothing (wool/synthetic)

    • Emotional stress/anxiety

    • Xerosis (dry skin)

    • Treat skin infections (S. aureus, herpes simplex)

  • Sunscreen/protection

  • Hydration/Emollients multiple times per day
    💡 Occlusiveness of topical preparations (from most to least): ointments (use for dry lesions) > creams (use for wet lesions) > lotions (use for weeping/intertriginous lesions)

Rule-out life-threatening conditions

  • Stevens-Johnson syndrome (<10% skin involved) / Toxic epidermal necrolysis (>30% skin involved)

    • Rare immune-mediated skin reaction, usually triggered by medications

    • Prodromal flu-like illness: Fever >39C, sore throat, rhinorrhea, cough, aches

    • Sudden onset tender/painful skin rash on face/limbs, 90% with involvement of mucous membranes (mouth, eyes, genital)

      • Tender red/purple macules, diffuse erythema, targetoid lesions, bullae and/or vesicles (may have positive Nikolsky)

    • Treat aggressively

      • Treat underlying trigger

        • Stop causative drug (commonly allopurinol, NSAIDs, antibiotics, antiepileptics)

        • Treat infections (eg. Mycoplasma pneumoniae)

      • Admission to ICU

      • IV fluid resuscitation and wound management

  • Necrotizing soft tissue infections (cellulitis, fasciitis, myositis, gas gangrene)

    • Mortality rate 20-80%

    • Diffuse erythema, swelling, warmth, shiny, exquisite tenderness

      • Late findings include crepitus, bullae, skin necrosis, loss of sensation

    • ↑ WBC, ↑ CRP/ESR, ↑ CK, subcutaneous air on XR/CT/MRI

    • ICU admission plus aggressive surgical exploration and debridement and broad-spectrum antibiotics: e.g., Tazo/Clinda/Vanco IV

  • Meningococcal infection

    • Can present with abnormal skin color pallor, mottling

    • Petechial rash involving trunk, lower body, mucous membranes (oral and ocular), may have purpura, ecchymotic lesions

  • Chemical or non-chemical burns

💡 When in doubt, consult Poison Control for additional guidance

  • Fluid Resuscitation for burns >15% BSA in children and >20% BSA in adults

    • Modified Brooke/Parkland Formula 2-4mL x %BSA x kg Ringer's Lactate, 1/2 in first 8 hours, 1/2 in next 16 hours

  • Wound management

    • Keep moist

    • Apply antibiotic ointment to non-adherent dressing (Adaptic) then apply to wound

    • Pain control

    • Ensure tetanus vaccine status up-to-date

  • Follow-up at <72h, to re-assess burn to better characterize partial vs. full thickness

    • Refer to burn center PRN

Rule-out serious pathology

  • Malignancy

    • Melanoma

      • ABCDE (Asymmetry, Border, Colour, Diameter >6mm, Evolving/elevation)

      • Subtype frequency: superficial spreading > nodular > lentigo maligna > acral lentiginous

      • Diagnosis and treatment: full-thickness excisional biopsy with 0.5-2cm safety margin (according to Breslow thickness)

        • Prognosis highly dependent on Breslow thickness, 5-year survival drops with depth > 1-2 mm

  • Basal Cell Carcinoma

    • Nodular BCC (most common) - raised pearly white nodule with telangiectasia >6mm

    • Superficial BCC - red scaling plaques with thready border

    • Diagnosis and treatment: full or partial-thickness biopsy (at edge of lesion to contain normal tissue)

    • Excellent prognosis (low rates of malignancy)

  • Squamous Cell Carcinoma

    • Persistent ulceration, crusting, hyperkeratosis, erythema

    • Treatment: Surgical excision + biopsy (e.g., punch biopsy, Mohs micrographic)

    • SCC In Situ: Bowen's disease

    • Pre-malignancy: Actinic keratosis (AK), Leukoplakia (oral)

      • Treat local AK with cryotherapy (eg. two freeze thaw cycles of 5s)

      • Treat widespread AK with fluorouracil 5% cream BID x 2-6 weeks

  • Cutaneous T-cell lymphoma (Mycosis Fungoides)

    • Lymphocyte infiltration in progressive stages (slow course over years)

    • Pruritus → oval or annular patches → thickened plaque → tumors

  • Pemphigus

💡 Not to be confused with the more common and less severe Pemphigoid blistering diseases (e.g., bullous pemphigoid)

  • Refers to a group of life-threatening autoimmune blistering and erosive diseases affecting the skin and mucosa (

    • Complications include infection, fluid loss, electrolyte disturbances

  • Types: Vulgaris (most common; 70% of all pemphigus), Foliaceus, IgA, Paraneoplastic

    • Treatment

      • Systemic steroids (1-2mg/kg prednisone daily or 0.5-1mg/kg in combination with rituximab)

        • Azathioprine or mycophenolate mofetil are often used to attempt to reduce steroids

        • Consider adjunctive high potency topical steroid (e.g., clobetasol propionate) for larger erosions

      • Cover erosions with antibiotic ointment or a bland emollient (eg, petroleum jelly) +/- non-adhesive wound dressings

Rule-out systemic disease

  • Granulomatosis with polyangiitis (Wegener’s)

    • Purpura in lower extremities, focal necrosis and ulcerations (may also include urticaria, livedo reticularis, nodules)

  • Systemic lupus erythematosus (SLE)

    • Acute

      • Malar (or butterfly) rash that resolves without scarring

      • Bullous, maculopapular, mucosal erosions/ulcerations, photosensitivity, hair loss

    • Subacute

      • Flat scaly patches, annular polycyclic lesions on trunk and arms

    • Chronic

      • Indurated hyperpigmented discoid plaques (most above neck)

  • Diabetes

    • Acanthosis nigricans (seen in most patients with childhood diabetes)

    • Diabetic dermopathy (30% of patients with diabetes)

      • Light brown/red oval/round scaly patches usually in pretibial area

  • Celiac

    • Dermatitis Herpetiformis ("Celiac of the skin")

      • Pruritic papulovesicular rash on extensor

      • Can biopsy to confirm celiac

    • Recurrent aphthous stomatitis

  • Drug reaction

    • Morbilliform/exanthematous drug eruption

    • Urticaria/angioedema

    • Severe cutaneous adverse reactions include drug hypersensitivity syndrome, SJS/TEN

    • Treat

      • Stop responsible drug

      • Emollients frequently

      • Topical corticosteroids (consider systemic if severe)

      • Antihistamines for urticaria

  • Kaposi's Sarcoma

    • Common in AIDS and following organ transplant

    • Purple/black papular lesions, most commonly affecting lower limbs, back, face, mouth, genitalia

Kaposi's Sarcoma



  • Types

    • Atopic

      • Inherited factors (family history of dermatitis or asthma)

      • Prevalent in children

    • Irritant contact

      • Water, detergents, solvents, harsh chemicals, friction

    • Allergic contact

      • Nickel, perfume, rubber, hair dye or preservatives

      • Consider patch testing

    • Nummular (discoid)

      • Possible prior injury

  • Treatment

💡 Ensure proper general skin care (see above)

  • Topical steroids (see table at bottom of page) applied sparingly BID x 2-4 weeks and re-assess

  • Topical calcineurin inhibitor for maintenance


  • Highly common contagious superficial bacterial infection (usually S. aureus or GAS), primarily affecting children aged 2-5

  • Local treatment

    • Topical mupirocin 2% ointment (Bactroban) TID x 5 days

    • Can consider topical fusidic acid (although some resistance)

  • Extensive treatment (widespread dispersion, multiple lesions, and/or fever)

  • Hand hygiene to prevent spread

  • May return to school 24h after effective antibiotic therapy

    • Draining lesions should be covered

Scabies (Sarcoptes scabiei)

  • Highly contagious parasitic skin infection characterized by intense pruritus (particularly at night when mites are most active)

  • Common in children, young adults, and people living in close proximity (e.g., child care facilities, nursing homes, prisons, refugee camps)

  • On exam:

    • Superficial linear burrows (primary lesions; top left image)

    • Small excoriated papules at fingers, wrists, elbows, axillae, areolae, periumbilical skin, waist, male genitalia, knees, buttocks, and feet (secondary lesion; middle and right images)

  • Diagnosed clinically (e.g., close contact with confirmed positive, pathognomonic rash) or with dermoscopy

  • Treatment: Topical permethrin 5% cream applied to the whole body from the neck to the soles of the feet, including areas under the fingernails and toenails (plus scalp in infants & young children) and washed off after eight hours. Can be repeated 1 week later if necessary.

    • Can manage pruritus with oral antihistamines or topical corticosteroids if severe

    • All textiles, bedding, clothing should be washed and dried at hottest temperature

    • Strongly consider prophylactic treatment for close contacts (even if asymptomatic as incubation period can be ~1 month)

    • Watch for superficial bacterial infection and treat accordingly with oral antibiotics

Last edited 2020-12-11
B. Paul, K. Chan


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