Pigmentation - physio, disorders, pigmented lesions Flashcards Preview

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Flashcards in Pigmentation - physio, disorders, pigmented lesions Deck (52)
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1
Q

What is melanin and its function

A
  • Pigmented polymer
  • protects DNA from UV radiation (200-2400nm)
  • deactivates free radicals
2
Q

What are the 3 types of melanin, location and production

A
  • Eumelanin (hair/skin)
    • Tyrosine ->(Tyrosinase) ->Eu-M
  • Pheomelanin (blond/red hair)
    • Tyrosine+cysteine ->(Tyrosinase) - >Pheo-M
  • Neuromelanin (Neural tissue)
    • unclear fx/production
3
Q

How/Where is melanin made and distributed?

A

In melanocyte

  • melanin in made in ER, packed in Gogi and released into melanomsome
  • Melanosome is distributed to keratinocyte via dendritic processes of melanocyte

In keratinocyte

  • melanosome is phagocytized into keratinocyte, and incorproated to cell membrane surrounding nuclei
4
Q

What are melanocytes, embryology, location in the body

A

Melanocytes are spindle cells that produce melanin

  • derived form neural crest cells in 10th wk GA
  • migrate to epidermis (s. basale), hair follicle, mucous membrane, dermis (then named nevus cells), neural tissue, eye, inner ear
5
Q

What is a nevus cell - and how does it differ from melanocyte?

A
  • Nevus cell is a melanocyte whic hhas migrated into dermis
  • Differs from melanocyte in that the nevus cell is:
    • round/spindle (vs. dendritic)
    • located in dermis (vs. s. basale)
    • lives in clusters (vs. individual)
  • Similar to melanocyte in that the nevus cell
    • has small nuclei
    • mitoses are rare
6
Q

What 4 pigments are responsible for skin color? (list chromophore)

A
  • Endogenous (melanocytes)->Brown w melanin
  • Exogenous (diet) ->Yellow/orange w carotene
  • Intravascular-> Blue w deoxyhemoglbin
  • Intravascular ->Red w oxyhemoglobin
7
Q

What determines the skin pigment at baseline?

A
  • Density of melanosomes in the keratinocyte and the density of melanin in each melanosome
  • Balance of Eumelanin (brown-blakc) vs Pheomelanin (yellow-red)
8
Q

What factors control the color of skin

A
  • Genetics
  • Hormonal control
    • melanotrophic hormones (MSH, ACTH, pregnancy, lipotropin)
  • UV - stimulates release of melanotrophics from keratinocytes which stimualtes melanocytes to produce more melanin
9
Q

What are hypopigmentary disorders

A
  • Vitiligo
  • Albinism
  • Waardenburg
  • Leptomeningeal melanocytosis
  • Neurocutaneous melanosis
10
Q

What is vitiligo

A

Hypopigment disorder with selective destruction of melnocytes in epidermis +/- follicles

  • Onset 10-30yo, progressive
  • sharply demarcated hypopigment macule which coalesce

Treatment

Non-op: Repigment with phototherapy, Depigment with hydroquinone, Tattoo

Operative: punch graft

11
Q

What is albinism

A

Congenital hypopigmentary disorder - no production of melanin

  • Onset birth
  • No pigment in hair, eyes, skin
  • normal density of melanocytes
12
Q

List types of Nevocellular Nevi

A

Acquired

  • Junctional nevus - at D-E jx
  • Compund nevus - in dermis and epidermis
  • Dermal nevus - in dermis only

Congenital

  • GCMN
  • Non-giant CMN

Special

  • Halo nevus
  • Spitz nevus
  • Atypical nevus
13
Q

When do acquired nevocellular nevi appear, change with age?

A
  • Not present at birth
  • progress from junctional ->compound ->dermal
14
Q

What is a giant CMN?

A
  • Pigmented nevus present at birth or shortly therafter, caused by abnormal migration of melanoblasts b/w 8-24th wk GA
  • link to c-met oncogene
15
Q

How is GCMN defined clinically

A

>20cm dimater

50% of body region

16
Q

What conditions are associated w GCMN

A
  • leptomeningeal melanocytosis
  • NF
17
Q

What are treatment options for GCMN?

A

Medical

  • observe (dermoscopy/photo)
  • Laser
  • dermabrasion
  • chemical peel

Surgical

  • Serial excision, Tissue expansion, local flaps
18
Q

What is the prognosis of GCMN

A
  • <4% malignant transformation , usually <age>
    </age><li>may lighten w age or nodular, hair growth</li>

</age>

19
Q

If child presents w GCMN, what are RFs for associated neurocutaneous melanosis

A
  • GCMN on midline trunk/calvarium
  • seizures, abnormal CNS development
  • multiple satellite lesions

Workup for? neurocutaneous melanosis

MRI <6mths of age

20
Q

What is a halo nevus?

A

Pigmented nevus w area of surrounding hypopigment

Treatment - expectant, excise if risk dysplastic nevus

21
Q

What is a spitz nevus?

A

Benign Juvenile melanoma (spindle cell nevus of reed)

  • Epid: majority <30yo, acquired or congenital
  • Presentation; common H&N, symmetric small well circumscribed pigmented papule

Treatment

  • observe
  • excise if changes/cosmesis
22
Q

What differentiates spitz nevus, atypical spitz nevus, malignant spitz?

A

Histology

  • nest of spindle nevus cells in variable levels of dermis
23
Q

What is your DDx of a congenital nevus?

A
  • Nevis spillus
  • beckers nevus
  • acquired nevus
  • lentigo nevus sebaceous
  • mongolian spot
  • cafe au lait
24
Q

List benign melanocytic lesions

A

Epidermal

  • Ephelis
  • Lentigo
  • Cafe au lait
  • becker nevus

Dermal

  • Blue nevus
  • mongolian blue spot
  • Nevus of Oto/Ito
25
Q

What is lentigo pathology, types and presentation

A
  • increased melanocytes in basal layer
  • Lentigo simplex (younger pt) associated w LEOPARD, LAMB, PEutz Jagher
  • Solar lentigo due to sun
  • Malingna lentigo
26
Q

What is an ephelide, pathology and presentation, treatment

A

Melanocytic lesion in the epidermis

  • increased melanin, normal # melanocytes
  • decrease in number w age

Tx

  • laser, cryo
27
Q

What is a Cafe au lait spot

A

Benign melanocytic lesion of the epidermis

  • increased # melanocytes + acanthosis
  • looks alike large brown patch
  • present at birth, fades w age
28
Q

What is a becker nevus

A

Benign HAIRY melanocytic lesion in ther epidermis

  • increase #melanocytes and melanin granules
  • appears in M, at puverty +/- hair, on back/shoulder, submammary

Treatment

  • depilation, laser may lighten
29
Q

What is a nevus spillus

A

Lentigo simplex ( melanocytic lesion in the epidermis) + smaller darker papule/macule

30
Q

What is associated w cafe au lait spots

A
  • McCune albright
  • NF 1/2
31
Q

What is your DDx for a pigmented macule <1cm

A
  • Lentigo (solar)
  • lentigo implex
  • lentigo maligna
  • LEOPARD syndrome
  • LAMB syndrome
  • Peutz Jeghers
  • dysplastic nevus
  • junctional nevus
32
Q

What is the tyndall effect

A

Red (long) wavelengths pass by melanin but the shorter wavelengths (blue) are scattered, with some going back to skin surface

33
Q

What is a mongolian spot

A

Congenital melanocytic lesion in dermis

  • increased # of melnaocytes
  • caused by abnornal migration of neural crest cells
  • located in sacrococcygeal region, most common in hispanic, asian, native american
  • uniform blue gray well demarcated lesion
  • FADE by 3-4yrs of age
34
Q

What is Nevus of ota and nevus of Ito

A

COngenital melanocytic lesion in the dermis

  • located in 1st or 2nd branchial arch (Oto)
  • or located on shoulder, deltoid, supraclav (Ito)
  • occur at birth OR puberty, F:M
  • confluence of blue black macules w associated brown spots

Treatment

Q-switched laser or NdYAG laser

35
Q

What is Hori’s Nevus

A

Congenital melanocytic lesion in dermis

  • looks like Nevus of Oto but bilateral and apepars in 40-50yo asians
36
Q

What is a blue nevus

A

Congenital melanocytic lesion in dermis

  • blue raised papule - may arise at any age
  • increased # of melnocytes
  • MM can arise from blue nevus
  • Assocaited with syndrome LAMB if multiple present
    • Lentiges
    • Atrial myxoma
    • Mucocutaneous myxomas
    • blue nevi
  • TREATMENT
    • excise if >10mm or changing- margin 3-5mm
37
Q

What is ur DDx of a blue nevus

A
  • Nodular melanoma
  • Cutaneous melanocytic melanoma
  • Kaposi sarcoma
  • Venous malformation
38
Q

What are premalingnat lesions for melanoma

A
  • GCMN
  • Lentigo melanoma
  • MIS
  • atypical/dysplastic nevus
39
Q

What is the histology of dysplastic nevus?

A
  • discontinuous priliferation of atypical melanocytes with nest formation intraepidermal
40
Q

What is the risk of melanoma from dyspalstic nevus?

A
  • DN is a RF for development of melanoma
  • DN is also a precursor for melanoma - 1/40 000 transform
41
Q

What is lentigo malingna and te pahtology

A

COnsidered melanoma in situ on sun damaged skin

Path

  • non-nested proliferation of atypical melanoctyes in an atrophic epidermis

Prognosis

  • up to 30% trasnform into MIS, LMM or desmoplastic melanoma
42
Q

WHat is MIS

A

Intraepidermal proliferation of atypical melnocytes w fully evolved atypia

  • most commonly melanoma arises form MIS
43
Q

What is FAMM

A

Familial Atypical Mole and Melanoma syndrome

  • FDR or SDR with MM
  • >50 nevi
  • AD inheritance

Prognosis

  • 10% risk of melanoma over 10yrs
44
Q

What are syndromes associated with melanocytic lesions

A
  • FAMM
  • Waardenburg syndrome
  • ALbright syndrome
  • LAMB syndrome
  • LEOPARD syndrome
  • Peutz Jegher syndrome
  • Central facial lentiginous
45
Q

What is waardenburng syndrome

A

Congenital ABSENCE of melanocytes in hair, skin, ears, stria vascularis of ear

Associated w CL/P 7%

AD, due to defect in migration of NCC and melanin synthesis

Clinical features

  • Skin; patchy hypo and hyperpigmented patches
  • Hair:premature greying/white forelock
  • Ear: SNL
  • Eye: heterochromia, isohypochromia (pale blue), blepharophimosis, telecanthus
46
Q

What is albright syndrome

A

Unilatreal polyostotic FD with cafe au lait spots and hyperfunctional endocrinopathies

47
Q

What is LEOPARD syndrome

A
  • Hypertelorism
  • lentigo
  • pulmonary stenosis
  • genital abnormalities
  • deafness
48
Q

What is peutz jegher

A
  • intestinal polyposis
  • mucosal lentigo
49
Q

What is LAMB syndrome

A
  • Lentigo
  • Atrial myxoma
  • Mucocutaneous myxoma
  • Blue nevi
50
Q

What is centrofacial lentiginosous

A
  • LEntigo simplex in horizontal band across face
  • craniofacial microsomia
  • CLP
51
Q

What is epidermal nevus syndrome

A
  • Craniofacial overgrowth
  • Digital gigantism
  • acquired nevocellular nevi
  • Vascular mlaformations (CNS or cutaneous)
52
Q

What is Neurocutaneous melanosis (= leptomeningeal melanocytosis)

A

Def. Nevocellular infiltrate into leptomeninges and brain parenchyma

Clinical features

  • hydrocephalus
  • seizure
  • focal neurologic deficits

Presents around 2yr

RFs

  • GCMN
  • Congenital nevocellular nevus at midline on scalp, neck, spine

Do MRI before 6mths

Treatment - symptomatic. Delay excision due to poor prognosis

Prognosis

  • asymptomatic: 60% risk of leptomeningeal melanoma (90% fatal)
  • symptomatic (90% mortality)