Variations in skin color are a result of differences in the amount and distribution of melanin within epidermal melanocytes and keratynocytes, rather than the number of melanocytes
JAMA āfrequency of skin biopsies for psoriasis by race and ethnicityā
- Twice as many biopsis in dark skin to diagnose psoriasis
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How to recognize erythema without seeing redness
- Palpate: warm in active inflammatory erythema
- Ask the patient: cellulitis, exanthema, erythema
- Look harder (dermoscopy)
- Base the diagnosis on other signs
- Smooth superficial papules and plaques and widening and spacing of follicular openings (peau dāorange like) in urticaria
- Thick silvery scales in psoriasis
- Fluexures, symmetry in atopic dermatitis
- Shawl sign & gotton papules (not red, may be white) in dermatomyositis
- Comedones in lupus (indicate perifollicular process)
- Consider black as red
- Look for siblings to know the baseline āblackā
- Limitation:
- Inflammation may lead to hypopigmentation after
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Fuchter-Voigtās ādemarcationā line
- represent a remanent of embryology
- Vertebrates have ventral face lighter pigmented than dorsal
- Less pigmentation on the anterior-internal side of the arm compared to the posterior-external area ā more visible in pigmented subjects
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Frictional melanosis
Acquired Dermal Melanocytosis
- AKA bilateral naevus of Ota-like macules ABNOM
- Naevus of Horis in Asia
Difficult to differentiate from melasma
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Ochronosis due to long term use of hydrochinone containing products skin lightening practices
- Papular/granular appearence
- Contrast between phalanx and articulations in fingers
- Dermatophitosis due to use of dermovate containing products
- SCC due to mercury containing products
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Psoriasis usually hypopigmented - keratinocytes donāt take melanossomes when they migrate upwards in the epidermis
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Lichen planus hypercheratotic difficult DDx from psoriasis. Silver hue in lichen planus
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Post inflammatory hypopigmentation
- Usually after bullous disease, toxidermias, contact dermatitis
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Lichen nitidus more frequent in skin of color because more visible, benign but quite persistent
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Scleroderma salt and pepper appearence
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Confluent macular hypomelanosis
- Usually patients already did cetoconazol shampo
- Propably due to dysbiosis of the skin
- Can be removed by antibiotics falled by UV light
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Seborrheic Macular hypopigmentation
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Fitzpatrick skin phenotype IV to VI
- Fitzpatrick classification was developed as a tool to classify how skin reacts to UV light not as a classification of skin color
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Eumalanin Human Skin Color Scale ā„ 50
- Uses eumelanin index
- Eumelanin 50 or above is pigmented skin
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Facial dermatosis in skin of color
AcneRosĆ”ceaTesaurismoseĀ
Lichen planus pigmentosus in Frontal Fibrosis Alopecia
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Post inflammatory Hyperpigmentation in relation to atopic eczema with lichen simplex chronicus (awaiting patch testing to exclude allergic contact dermatitis)
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Leprosy
Granulomatous reaction to soft tissue filler material
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