Dermatology
Seán Keenan
2022
,Patterns of Skin Disease
Hypopigmented and Depigmented Lesions Hyperpigmented Lesions
Pityriasis versicolor Lentigos
- Sx: Superficial slightly scaly infection - Sx: Persistent brown, irregular macules
- Cx: Malassezia furfur (yeast) - Cx: Lentigo maligna = Subtype of melanoma in situ
- NB: Appears hypopigmented on darker skin - Cx: Solar lentigos = Sun-damaged skin in elderly
Pityriasis alba - Ix: Dermoscopes ± Full-thickness biopsy
- Sx: Hypopigmented skin - Mx: Excision >5 mm margins
- Cx: Post-eczema - NB: Larger than freckles and persist in winter
- NB: Often affects children faces Café-au-lait spots
Vitiligo - Sx: Faint brown macules
- Sx: Smooth depigmented patches or macules - Cx: If >5 in number consider neurofibromatosis
- Cx: AID – Primarily Thyroid disease Melasma (AKA Chloasma)
- Mx: ↓UV exposure; Topical steroids; UVA/UVB - Sx: Smooth brown patches especially on face
- Cx: Related to pregnancy or OCP use
Ring-Shaped Lesions Melanocytic naevi
Basal Cell Carcinoma - Sx: Moles
- Sx: Pearly papule + Central ulcer - Mx: Excision if suspicious or ↑ risk
Tinea Seborrhoeic Warts / Keratoses
- Sx: Scaly & itchy lesions with central healing - Sx: Benign greasy-brown warty lesions
- Cx: Ringworm (dermatophytosis) - NB: Affects back, chest and face; Esp. elderly
Granuloma Annulare Systemic Diseases
- Sx: Chronic inflammatory ~1 cm ring-shaped lesion - Addison’s disease
- Cx: Idiopathic o NB: Affects palmar creases, oral mucosa, scars
- NB: Often affects back of hands - Haemochromatosis
Erythema Multiforme o NB: Mostly on sun exposed skin (face)
- Sx: Target-like lesions - Porphyria cutanea tarda
- NB: Often affects extensor surfaces o NB: Lesions + skin fragility + blisters
Round, Oval, or Coin-Shaped (Discoid) Lesions Linear Lesions
Bowen’s Disease Köbner Phenomenon
- Sx: Slow-growing red, scaly plaque - Sx: Lesions related to skin injury (e.g. scratches)
Discoid Eczema - Cx: Multiple (Psoriasis; Molluscum contagiosum)
- Sx: Itchy, crusted/scaly eczema Dermatitis Artefactor
- NB: Worsened by heat - Sx: Bizarre-shaped lesions
Psoriasis - Cx: Self-inflicted by patient
- Sx: Well-defined scaly red/pink plaques Herpes Zoster
- ΔΔ: Discoid eczema (affects different surfaces/areas) - Sx: Vesicles / pustules
- NB: Affects extensor surfaces, scalp and natal cleft - NB: Follow dermatome (esp. trunk/ophthalmic)
Pityriasis Rosea Scabies Burrow
- Sx: Herald patch; Oval lesions with scaly edge - Sx: White/grey, track-like, raised burrow on skin
Erythema Migrans - Cx: Sarcoptes scabiei (Scabies mite)
- Sx: Bulls-eye rash Cutaneous Larval Migrans
- Cx: Pathognomic of Lyme disease - Sx: Itchy red pruritic eruption (Creeping eruption)
Impetigo - Cx: Hookworm infx (esp. Ancylostoma)
- Sx: Well-defined red patches + honey-coloured crust - NB: See hookworm in infectious disease notes
Pruritis
Presentation Management
- Sx: Excoriations; Lichenification; Papules; Nodules - Emollients: Dry skin
Causes - Antihistamines: Prochlorperazine;
- Common: Dry and older skin affected more - Steroids: Hydrocortisone
- Drugs: Aspirin; Penicillin; NSAIDs; Opioids - Jaundice: Cholestyramine
- Infx: Tinea; Lice; Insect bites; Scabies - Severe: Phototherapy
- Other: Jaundice; Photodermatitis; Allergies (urticaria)
, Terminology for Describing Lesions
Asymmetry Borders Colour Diameter Evolving
Seán Keenan
2022
,Patterns of Skin Disease
Hypopigmented and Depigmented Lesions Hyperpigmented Lesions
Pityriasis versicolor Lentigos
- Sx: Superficial slightly scaly infection - Sx: Persistent brown, irregular macules
- Cx: Malassezia furfur (yeast) - Cx: Lentigo maligna = Subtype of melanoma in situ
- NB: Appears hypopigmented on darker skin - Cx: Solar lentigos = Sun-damaged skin in elderly
Pityriasis alba - Ix: Dermoscopes ± Full-thickness biopsy
- Sx: Hypopigmented skin - Mx: Excision >5 mm margins
- Cx: Post-eczema - NB: Larger than freckles and persist in winter
- NB: Often affects children faces Café-au-lait spots
Vitiligo - Sx: Faint brown macules
- Sx: Smooth depigmented patches or macules - Cx: If >5 in number consider neurofibromatosis
- Cx: AID – Primarily Thyroid disease Melasma (AKA Chloasma)
- Mx: ↓UV exposure; Topical steroids; UVA/UVB - Sx: Smooth brown patches especially on face
- Cx: Related to pregnancy or OCP use
Ring-Shaped Lesions Melanocytic naevi
Basal Cell Carcinoma - Sx: Moles
- Sx: Pearly papule + Central ulcer - Mx: Excision if suspicious or ↑ risk
Tinea Seborrhoeic Warts / Keratoses
- Sx: Scaly & itchy lesions with central healing - Sx: Benign greasy-brown warty lesions
- Cx: Ringworm (dermatophytosis) - NB: Affects back, chest and face; Esp. elderly
Granuloma Annulare Systemic Diseases
- Sx: Chronic inflammatory ~1 cm ring-shaped lesion - Addison’s disease
- Cx: Idiopathic o NB: Affects palmar creases, oral mucosa, scars
- NB: Often affects back of hands - Haemochromatosis
Erythema Multiforme o NB: Mostly on sun exposed skin (face)
- Sx: Target-like lesions - Porphyria cutanea tarda
- NB: Often affects extensor surfaces o NB: Lesions + skin fragility + blisters
Round, Oval, or Coin-Shaped (Discoid) Lesions Linear Lesions
Bowen’s Disease Köbner Phenomenon
- Sx: Slow-growing red, scaly plaque - Sx: Lesions related to skin injury (e.g. scratches)
Discoid Eczema - Cx: Multiple (Psoriasis; Molluscum contagiosum)
- Sx: Itchy, crusted/scaly eczema Dermatitis Artefactor
- NB: Worsened by heat - Sx: Bizarre-shaped lesions
Psoriasis - Cx: Self-inflicted by patient
- Sx: Well-defined scaly red/pink plaques Herpes Zoster
- ΔΔ: Discoid eczema (affects different surfaces/areas) - Sx: Vesicles / pustules
- NB: Affects extensor surfaces, scalp and natal cleft - NB: Follow dermatome (esp. trunk/ophthalmic)
Pityriasis Rosea Scabies Burrow
- Sx: Herald patch; Oval lesions with scaly edge - Sx: White/grey, track-like, raised burrow on skin
Erythema Migrans - Cx: Sarcoptes scabiei (Scabies mite)
- Sx: Bulls-eye rash Cutaneous Larval Migrans
- Cx: Pathognomic of Lyme disease - Sx: Itchy red pruritic eruption (Creeping eruption)
Impetigo - Cx: Hookworm infx (esp. Ancylostoma)
- Sx: Well-defined red patches + honey-coloured crust - NB: See hookworm in infectious disease notes
Pruritis
Presentation Management
- Sx: Excoriations; Lichenification; Papules; Nodules - Emollients: Dry skin
Causes - Antihistamines: Prochlorperazine;
- Common: Dry and older skin affected more - Steroids: Hydrocortisone
- Drugs: Aspirin; Penicillin; NSAIDs; Opioids - Jaundice: Cholestyramine
- Infx: Tinea; Lice; Insect bites; Scabies - Severe: Phototherapy
- Other: Jaundice; Photodermatitis; Allergies (urticaria)
, Terminology for Describing Lesions
Asymmetry Borders Colour Diameter Evolving
