How to decide level of Melanin in pigmentation disorders

Clinical Colour and level of melanin

See Table below

 

Level of colour	Clinical colour	Disease eg
a) Intraepidermal only	Black	Melanoma in situ (lentigo maligna)
b) Basal epidermis/ Dermoepidermal junction	Brown	Lentigine Junctional nevus Café-au-lait macules Melasma
c) Superficial dermis	Purple/Violaceous	Lichen planus Fixed drug eruption
d) Deep dermis	Blue/Grey	Mongolian spot Nevus of Ota Nevus of ito

 

 Intraepidermal (Black)

Intraepidermal Lentigo melanoma (melanoma-in-situ-  Ref: dermnetz)

  

Basal epidermal and Dermo-epidermal Junction (Brown)

Junctional Nevus (Ref: Dermnetz)

Cafe-au-Lait macule in Neurofibromatosis

Lentigines on face

Melasma (Ref: DermQuest)

Superficial Dermal (purple/ violaceous)

Lichen Planus- Violaceus Papules (Ref: DermQuest)

Purple/ Violaceous papules in lichen planus

violaceous lesions in Fixed drug eruption (Ref: DermQuest)


Deep Dermal (blue/grey)

Nevus of Ota- This a congenital blue coloured nevus along ophthalmic and maxillary nerves (Ref: DermQuest)

Mongolian Spot-  This a congenital blue coloured nevus on lower back and sacrum (Ref:DermQuest)

Some tips in an MCQ

1) blue around eyes, on sclera and cheek since birth-unilateral is ALWAYS " nevus of ota"

2) blue on shoulder girdle since birth- ALWAYS "nevus of ito"

3) blue on lumbosacral region in a child since birth- ALWAYS "mongolian spot"

4) brown patch bilaterally on cheek- ALWAYS melasma/chloasma

Guttate psoriasis-photofeature

A child presents with few small erythematous papules with minimal scaling on trunk and arms. His parents report a recent sorethroat. What is the likely diagnosis?

Answer: Guttate Psoriasis

Expl: 

Introduction

• It is derived from the Latin word gutta, meaning drop (Guttate psoriasis is a type of psoriasis in which there are small, separated teardrops like lesions)

• The role of infection (tonsillar Streptococcus pyogenes infection) in precipitating guttate psoriasis is well known.  Infection often precedes the eruption by 2-3 weeks.

Clinical feature

• It is particularly common in children

• Common sites are the arms, legs, and torso.

• Acute onset of small, 1-10 mm diameter, droplike, erythematous papules, usually with a fine scale (generally the classical silvery scale is not easily seen)

How does streptococcus cause Guttate psoriasis ?

• Still under debate. 

• It has been suggested that streptococcal M protein may be similar to keratin in skin and hence leads to a molecular mimicry immunological response towards keratinocytes instead of the original streptococcus. This cross- reactivity between streptococcal antigens and keratinocyte components could explain the initiation of a disease process. 

Treatment

• There is no firm consensus on specific treatment algorithms

• Antibiotics to eradicate streptococcus are often started. Eg: ß -lactum antibiotics, Erythromycin,rifampicin etc

Prognosis

• Episodes may recur, especially those due to pharyngeal carriage of streptococci

• Generally, the disease is self-limiting, but a certain percentage of cases progress to chronic plaque psoriasis.

Hypopigmented patch on face- how to decide diagnosis in an MCQ- Important MCQ

A year old girl presents with ill defined hypopigmented patches on cheek with fine scaling. Her mother has a history of asthma. 

The best possible diagnosis is

a) Indeterminate hansens

b) Pityriasis alba

c) Pityriasis versicolor

d) Atopic dermatitis

Ans: b

Expl:

         

Pointer words for diagnosis of hypopigmented patch on cheek in children

Look for these phrases-	Diagnosis
Single/ few hypopigmented patches on cheek with fine scaling. No atrophy. Normal sensations on patch Personal/ family h/o atopy in the questions (eg: asthma, recurrent URTI, etc) Lesions come and go	Pityriasis alba (pityriasis= powder)
Single/ Few hypopigmented patches on cheek. No scaling Lesions show mild atrophy Sensations are usually normal Child from endemic areas like Bihar/ UP/ West Bengal,Tamil Nadu, etc	Indeterminate hansens
Multiple hypopigmented macules/ patches with scaling on scratching (scratch sign). Usually MCQ will say “multiple lesions on chest and trunk”, sometimes face. Perifollicular hypopigmentation (this word is often present in questions) Can occur in multiple shades of colours (brown/ hypopigmentated/red/pink) Woods lamp-greenish yellow fluorescence. KOH smear positive (spaghetti and meat ball appearance) no h/o atopy in the question	Pityriasis versicolor
Depigmented patches with/without leucotrichia (white hair)	Vitiligo
Depigmented/hypopigmented circular macule over centre of forehead in a female	Leucoderma due to bindi (agent causing it is para-tertiary butyl phenol)

                                   

Why not P. versicolor in this MCQ- see pic below ?

Typical pityriasis versicolor
Note the number of lesions. On scratching there will be fine scaling
(Ref:ehow)

Typical pityriasis versicolor on face

Note the number of lesions. On scratching there will be fine scaling

(Ref:skinsight.com)

Why not Atopic dermatitis?

                                           Typical atopic dermatitis in children (Ref:www.salineherapy.com)

    Note erythema, oozing and inflammation
 (Atopic dermatitis is itchy, P.alba is not.There is no hypopigmentation in atopic dermatitis)

     

Also, for diagnosis of atopic dermatitis, these criteria have to be fulfilled: 

Typical Adult atopic dermatitis

Note the erythema, oozing and inflammation in flexure of knee

(Ref:www.derm-image.org)

Above: Typical change in sites of lesions in atopic dermatitis with age groups

Typical bindi leucoderma on central forehead

Note the depigmentation and white hairs

Discoid lupus erythematosus

Erythematous scaly plaques on scalp, causing scarring alopecia. Notice the hyperpigmented borders and atrophic (=thin, hypopigmented) central area

Typical site- Auricular and Pre-auricular area

Erythematous scaly plaques with adherent scale, causing scarring alopecia. Notice the variable pigmentation with depigmentation in occipital area and hyperpigmented border (on right side)

 

In Brief

• Lupus erythematosus (LE) is usually divided into two main types: DLE and SLE
• Discoid lupus erythematosus (DLE) generally occurs in young adults, with women outnumbering men 2:1 (Discoid= Disc-like)
• DLE can be subdivided into a localized form (localized DLE) in which lesions are confined to the face above the chin, the scalp and the ears, and a disseminated form (Disseminated DLE) in which lesions go below the neck.

Presentation

• Discoid lesions are usually localized above the neck. Favored sites are the scalp, bridge of the nose, malar areas, lower lip, and ears.
• Usually, lesions occur as well-defined erythematous plaques.
• There is adherent scale in many cases (as is seen in photo) and when this is removed its undersurface shows horny plugs which have occupied underlying dilated pilosebaceous canals (When not obscured by scaling, these dilated follicular openings may be seen clinically as well). This so-called ‘tin-tack’ sign or carpet tack sign or langue du chat (cat’s tongue) sign.-    MCQ
• Scarring alopecia ensues- (cause of scarring alopecia. SLE causes both scarring and Non-scarring alopecia) MCQ
• Itching and tenderness are common. 

Investigation

1) Histology- Investigation of choice MCQ - 2 out of 3 should be present

• Degenerative changes in the dermal connective tissue, consisting of hyalinization, oedema and fibrinoid change in upper dermis. Thickening of the basement membrane zone and dermal mucin deposition
• Liquefaction degeneration of the basal cell layer of the epidermis
• A patchy dermal lymphocytic infiltrate with a few plasma cells and histiocytes, particularly around the appendages, which may be atrophic

 

                                             (Ref: http://pixshark.com/discoid-lupus-erythematosus-histopathology.htm)

 (Ref: IJDVL)

2) ANA – Antinuclear antibodies are found in between 5-60% of cases depending on patient selection and laboratory techniques: the ‘homogeneous’ type of antinuclear factor being twice as frequent as the ‘speckled’ type. 

Treatment

Exposure to sunlight must be avoided, and a high sun-protection factor (SPF) sunscreen should be used daily

Treatment chart for DLE

Topical	Systemic
Steroids Potent or superpotent topical corticosteroids are beneficial. The single most effective local treatment is the injection of corticosteroids into the lesions. Triamcinolone acetonide, 2.5–10 mg/mL, is infiltrated into the lesion through a 30-gauge needle at intervals of 4–6 weeks.	1) Antimalarials The safest class 2) Acitretin Second-line agents and are particularly helpful in treating hypertrophic DLE

Complication

1)  Rate of progression to SLE- Extra edge point MCQ

- Localised DLE- 1.2% risk

- Disseminated DLE- 22% risk

- Females with DLE before< age of 40 years with HLA-B8, have an increased risk

- Patients with DLE showing signs of nephropathy, arthralgia and ANA titres of 1 : 320 or more should be carefully monitored

2) Rarely, aggressive squamous cell carcinoma arises in long-standing lesions of DLE.

Topical

Systemic

Steroids

Potent or superpotent topical corticosteroids are beneficial. The single most effective local treatment is the injection of corticosteroids into the lesions. Triamcinolone acetonide, 2.5–10 mg/mL, is infiltrated into the lesion through a 30-gauge needle at intervals of 4–6 weeks.

1) Antimalarials

The safest class

2) Acitretin

Second-line agents and are particularly helpful in treating hypertrophic DLE