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