Melanocytes and Pigmentation Disorders Flashcards Preview

MSS Weeks 3-5 > Melanocytes and Pigmentation Disorders > Flashcards

Flashcards in Melanocytes and Pigmentation Disorders Deck (16)
1

Melanocytes

  • Produce pigment
  • Dendritic cell
    • Extend to multiple keratinocytes to facilitate melanin transfer
  • Epidermal-melanin unit:
    • Melanocyte and its surrounding keratinocytes

2

From where are Melanocytes derived ?

Neural Crest

3

Pigmentation Variance

  • Melanocyte number and density does not vary by race
  • Pigmentation dependent on the size, number, and density of melanosomes (pigment granules in keratinocytes)

4

Melanosome formation

As follows:

5

Classifications of pigment

  1. Hyperpigmentation - Darker than surrounding or normal color; increased pigment
  2. Hypopigmentation - Lighter than surrounding skin; decreased pigment
  3. Depigmentation - White; no pigment
  • Wood's light exam - Help differentiate "white" areas from "light" areas

6

Tuberous Sclerosis (Genetics,pathophysiology, incidence, findings)

  • Autosomal dominant genetic disorders: TSC1 (hamartin), TSC2 (tuberin) mutations
  • Pathophys: Non-malignant tumors of the brain, eyes, heart, kidney, skin and lungs
  • Birth incidence: 1/5800 to 1/10,000
  • Findings: 3 or more hypopigmented macules (early), adenoma sebaceum (angiofibromas and fibrous plaque), shagreen patch, periungual fibromas

7

Vitiligo (Mechanism, typical course, findings)

  • Mechanism - T-cell mediated autoimmune disorder, destruction of melanocytes with subsequent development of depigmented patches
  • Course - Typically acquired, progressive course is typical
  • Clinical findings - Hair in affected area often becomes white (poliosis): Hands, knees, feet, genitals depigmented (typically symmetric)

8

Oculocutaneous Albinism (Genetics, Mechanism, Finding)

  • Genetic disorders (Autosomal dominant or recessive)
  • Defect in tyrosinase or related proteins resulting in impaired melanin production
  • White to yellow/red hair with light to white skin

9

Various brown spots

  • Ephelides - Freckles
  • Cafe au lait macules
  • Solar lentigo/lentignes
  • Dermal melanocytosis
  • Melanocytic nevi (acquired vs congenital)

10

Neurofibromatosis 1 (NF1): Genetics, incidence, findings

  • Von Recklinghausen's disease
  • Autosomal dom. mut. in neurofibromin
  • Up to 50% spontaneous mutations
  • Birth Incidence: 1/3000
  • Skin:
    • Cafe-au-lait pigmentation
    • axillary/inguinal freckling
    • neurofibromas

11

Solar Lentigo

  • "Age spots/liver spots"
  • Sun exposed area, larger than ephelides
  • Correlated with sunburn

12

Dermal Melanocytosis

  • "Mongolian spot"
  • Deeper pigment (lower dermis) creates bluish colors
  • Lumbrosacral location most common - Fading over time typical in this location

13

Acquired Melanocytic Nevi

  • Subtypes: More histologic significance than clinical
    1. Compound
    2. Junctional
    3. Intradermal

14

ABCDE of Nevi

  • Screening for risk to melanoma: (ABCDE)
    1. Asymmetry
    2. Border irregularity/blurred border
    3. Color heterogenity
    4. Diameter > 6 mm *
    5. Evolution or change

* Not applicable to congenital lesions

15

Large (Giant) CMN

  • Higher risk for melanoma than smaller CMN
  • Risk for neurocutaneous melanosis
    • Menigeal melanosis or even melanoma >20 cm in adult
  • Excision often not possible

16

What is the typical ratio of kerotinocytes to melanocytes?

10:1

(kerotinocytes:melanocytes)