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Dermatology Board Prep > DERM (09) Genodermatoses > Pigmentary Disorders > Flashcards

Pigmentary Disorders Flashcards

1
Q

What is the inheritance pattern for oculocutaneous albinism?

A

There are 4 different types, all AR

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2
Q

What is the underlying pathology of oculocutaneous albinism?

A

Abnormal melanin and melanosome biosynthesis and transport

  • Occurs in the skin, hair follicles and eyes
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3
Q

What is the most common type of oculocutaneous albinism?

A

Type II (OCA2 gene affected)

  • Type I is the second most common type
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4
Q

What type of oculocutaneous albinism do melanocytic lesions not occur in?

A

These do not occur in classic OCA1a, otherwise these lesions form in the other types

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5
Q

What are the eye sx’s associated with oculocutaneous albinism?

A

Photophobia, nystagmus, and reduced visual acuity of variable severity

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6
Q

What is the histology of oculocutaneous albinism?

A

Decreased melanin content but normal melanocyte count

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7
Q

Is there a difference in skin cancer risk among those with oculocutaneous albinism?

A

Increased risk of BCC, SCC (most common type of skin cancer in these patients), melanoma (worse w/ OCA1)

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8
Q

In what conditions can an OCA2-like hypopigmentation be seen in and why?

A

Can be seen in Prader-Wili syndrome and Angelman syndrome which are caused by deletions on chromosome 15q (has the OCA2 gene on it) and occurs if the remaining version of 15q has a mutation on it in the OCA2 gene

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9
Q

What gene is mutated and what is the “phenotype” for OCA1a?

A

TYR (absent), tyrosinase negative

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10
Q

What are the clinical findings in oculocutaneous albinism type 1a (OCA1a)?

A
  • Generalized and near-complete lack of pigmentation at birth – white hair and skin (hair becomes light yellow over time)
  • Nevi are amelanotic/pink
  • Gray-blue irides
  • Markedly reduced visual acuity, severe photosensitivity, markedly
  • increased risk of SCC
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11
Q

What are the clinical findings in oculocutaneous albinism type 1b (OCA1b)?

A
  • No pigmentation of skin/hair at birth but over time, can develop some pigmentation.
  • Can have amelanotic or pigmented nevi
  • Milder ocular complications compared to OCA1a
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12
Q

What is temperature sensitive OCA1b?

A

Temperature sensitive variant (OCA1b TS): tyrosinase functions at low temperatures, leading to hair pigmentation at cooler anatomic sites (mainly extremities) and white hairs in warmer sites (trunk, intertriginous zones)

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13
Q

What is the gene affected and the “phenotype” of OCA1b?

A

TYR (decreased to 5-10% of normal functioning)

  • Phenotype: “Yellow mutant albinism” minimal pigment
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14
Q

What is the gene affected and the “phenotype” of OCA 2?

A

OCA2 gene (Was called P gene previously; pink-eyed dilution)

Tyrosinase + phenotype

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15
Q

What are the clinical findings in OCA type 2?

A

Most common OCA, usually seen in Africans (Sub-Saharan African populations)

  • Pigmentary dilution variable, but develop pigmented nevi/lentigines over time
  • Light brown hair and gray/tan irides
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16
Q

What is the gene affected and the phenotype of the OCA type 3?

A

TYRP1

Phenotype: “Rufous”

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17
Q

Clinical findings in OCA type 3?

A

Very rare

  • most commonly occurs in Africa and New Guinea Reddish-bronze skin and red hair color
  • Blue-brown irides
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18
Q

What is the gene affected and the phenotype of OCA type 4?

A

Gene: Solute carrier family 45 member 2 (SLC45A2)

Phenotype: Resembles OCA2

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19
Q

What are the clinical manifestations of OCA type 4?

A
  • Extremely rare outside of Japan (where it accounts for 25% of OCA)
  • Variable clinical presentation ranging from white skin/hair to mild pigmentation of skin/yellow-brown hair
  • Distinguished from OCA2 via molecular studies
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20
Q

What are the 3 silvery hair syndromes?

A

Chediak-Higashi syndrome, Griscelli syndrome, and Elejalde syndrome

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21
Q

What is the mode of inheritance for the Silvery hair syndromes?

A

AR for all

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22
Q

What is the overall phenotype of the Silvery hair syndromes?

A

All have pigmentary dilution of the skin and hair w/ variable immunologic and neurologic features

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23
Q

What are the histologic findings in the Silvery hair syndromes?

A
  • Light microscopy: Giant granules or melanosomes can be seen in hair shaft and keratinocytes
  • Skin bx: hyperpigmented oval melanocytes and poorly pigmented adjacent karatinocytes
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24
Q

How many types of Griscelli syndrome are there?

A

3 (Types I-III)

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25
Q

What are the differences between the 3 types of Griscelli syndrome?

A
  • All have pigmentary dilution of the skin and hair
  • Type I: Severe neurologic impairment developing during early childhood
  • Type II: Combined T and B-cell immunodeficiency which leads to numerous infections and hemophagocytic syndrome
  • Type III: Least severe, mostly just has the cutaneous findings
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26
Q

What is the clinical findings of Chediak-Higashi syndrome?

A

Severe multisystem disease

Starts in infancy w/ silvery hair, oculocutaneous albinism, immunodeficiency, bleeding diathesis, and neurologic degeneration

  • Death usually occurs by age 10 from lymphoproliferative accelerated phase/hemophagocytic syndrome (Presents w/ pancytopenia and lymphocytic infiltration of liver/spleen/lympho nodes
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27
Q

What is the most common cause of death in Chediak-Higashi syndrome?

A

Death usually occurs by age 10 from lymphoproliferative accelerated phase/hemophagocytic syndrome (Presents w/ pancytopenia and lymphocytic infiltration of liver/spleen/lymph nodes

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28
Q

What is the characteristic finding on peripheral blood smear in patients w/ Chediak-Higashi syndrome?

A

Peripheral blood smear: Characteristic giant granules within cytoplasm of neutrophils, eosinophils, platelets, melanocytes and granulocytes

Bone marrow bx/smear: Giant inclusion bodies within leukocyte precursors

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29
Q

What is Elejalde syndrome?

A

Pigmentary features of Griscelli syndrome + severe neurologic dysfunction without immunodeficiency (may represent a variant of GS1)

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30
Q

What is the gene defect in Chediak-Higashi syndrome?

A

LYST/CHS1

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31
Q

What is the cellular defect from LYST/CHS1 mutation in Chediak-Higashi syndrome?

A

Impaired biosynthesis and storage of melanosomes, platelet dense granules, and lysosomes within leukocytes

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32
Q

What is the appearance of the trichoscopy clumps of melanin in Chediak-Higashi syndrome?

A

Small, regularly spaced

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33
Q

What is the appearance of the melanocytes in Chediak-Higashi syndrome?

A

Giant melanosomes

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34
Q

The appearance of neutrophils in Chediak-Higashi syndrome?

A

Giant granules

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35
Q

Differences in ocular findings in Chediak-Higashi syndrome compared with Griscelli syndrome?

A

There are no ocular findings in Griscelli as compared with Chediak-Higashi syndrome

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36
Q

Bleeding abnormalities in Chediak-Higashi syndrome and Griscelli syndrome?

A

There are no bleeding issues in Griscelli syndrome, there is in Chediak-Higashi syndrome due to issues w/ platelets = increase in bleeding time and bleeding diathesis

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37
Q

Are recurrent infections seen in Chediak-Higashi syndrome and Griscelli syndrome?

A

Yes in Chediak-Higashi syndrome and only in Griscelli syndrome type 2

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38
Q

What types of infections occur in Chediak-Higashi syndrome?

A

Skin, lungs, and upper respiratory

  • Can have EBV-induced lymphoproliferative syndrome
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39
Q

Which silver hair syndrome can cause severe gingivitis, periodiontis, and oral mucosal ulceration?

A

Chediak-Higashi syndrome

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40
Q

What is the most severe complication of Griscelli syndrome type I

A

Neurologic sequelae

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41
Q

Which form of Griscelli syndrome is usually mild and skin-limited?

A

Griscelli type 3

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42
Q

In what silver hair syndromes does an accelerated phase occur?

A

Chediak-Higashi syndrome = 85%

Also occurs in Griscelli syndrome type II

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43
Q

Which silver hair syndromes have neurologic disorder?

A

Progressive deterioration seen in Chediak-Higashi syndrome

  • Also in type I Griscelli syndrome
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44
Q

What is the gene mutation in Griscelli syndrome type I and what is the resulting pathophysiology?

A

MY05A - Aberrant translocation of melanosomes along microtubules within melanocytes

45
Q

What is the gene mutation in Griscelli syndrome type II and what is the resulting pathophysiology?

A

RAB27A - Results in aberrant translocation of melanosomes along microtubules within melanocytes

46
Q

What is the gene mutation in Griscelli syndrome type III and what is the resulting pathophysiology?

A

MLPH - Aberrant translocation of melanosomes along microtubules within melanocytes

47
Q

What are the major types of tissues affected by mutations in the MYO5A gene seen in Griscelli syndrome type I?

A

Melanocytes, CNS

48
Q

What are the major types of tissues affected by mutations in the RAB27A gene seen in Griscelli syndrome type II?

A

Melanocytes, Cytotoxic T-cells

49
Q

What are the major types of tissues affected by mutations in the MLPH gene seen in Griscelli syndrome type III?

A

Melanocytes only

50
Q

What are the genes are involved and what is the inheritance pattern involved in Hermansky-Pudlak syndrome?

A

9 genes involved: HPS1, AP3B1/(HPS2), HPS3, HPS4, HPS5, HPS6, DTNBP1/(HPS7), BLOC1S3/(HPS8), and BLOC1S6 (HPS9)

-AR

51
Q

Clinical appearance of Hermansky-Pudlak syndrome?

A

Oculocutaneous albinism, bleeding diathesis (platelet storage pool defect) and lysosomal accumulation of ceroid lipofuscin

52
Q

Pathogenesis of Hermansky-Pudlak syndrome?

A

Disorder of biogenesis of melanosomes and other lysosomal-related organelles, such as platelet dense granules

53
Q

In what population is Hermansky-Pudlak more common in?

A

Puerto Ricans (HPS1), dutch, and Indians of Madras

54
Q

Features of albinism in Hermansky-Pudlak?

A

Variable level of pigmentary dilution in the skin, hair (slight sheen), and the irises are pale

55
Q

What are the blood-related issues seen in Hermansky-Pudlak?

A

Has platelet dysfunction, so there are extensive ecchymoses, nosebleeds, and menorrhagia

56
Q

What medications need to be avoided in Hermansky-Pudlak?

A

Aspirin and anti-platelet medications

57
Q

What eye findings are seen in Hermansky-Pudlak?

A

Photophobia, strabismus, and nystagmus

58
Q

What organs can be affected in Hermansky-Pudlak?

A

Granulomatous colitis, progressive pulmonary fibrosis, cardiomyopathy, and renal failure from lysosomal ceroid accumulation

59
Q

What are the histologic findings in Hermansky-Pudlak?

A

Non sun-exposed skin = decreased number of melanosomes and short dendritic processes

60
Q

What is the prognosis of patients in Hermansky-Pudlak?

A

Life expactancy = 30-50 yrs

Most common cause of death is pulmonary fibrosis

61
Q

Most common cause of death in Hermansky-Pudlak?

A

Pulmonary Fibrosis

62
Q

Are rates of skin cancer affected in Hermansky-Pudlak?

A

Increased rates of skin cancer

63
Q

What is the affected gene and mode of inheritance in piebaldism?

A

c-KIT proto-oncogene or deletions in snail family zinc finger 2 (SNAI2, SLUG)

AD

64
Q

What is the underlying pathology of piebaldism?

A

Defective migration of melanoblasts from neural crest to the ventral midline and fialed differentiation of melanoblasts to melanocytes

65
Q

Clinical appearance in piebaldism?

A

White forelock (poliosis = in 90%) + congenital patterned midline adn ventral patches of leukoderma

66
Q

Prognosis of piebaldism?

A

Depigmentation is stable and permanent, but there are otherwise no systemic symptoms/associations = benign

67
Q

What is a key clinical distinguisher of piebaldism vs nevus depigmentosus/vitiligo?

A

Islands of normal and hyperpigmentation within depigmented patches

68
Q

How many types of Waardenburg syndrome are there?

A

4 clinical types (WS 1-4)

69
Q

What is the inheritance pattern of the Waardenburg syndromes?

A

AD

70
Q

What is the underlying pathology in Waardenburg syndromes?

A

Absence of melanocytes in the skin/hair/eyes/striae vascularis of the cochlea

71
Q

What are the general clinical features in Waardenburg syndromes?

A

Depigmented patch on the forehead w/ white forelock (poliosis), congenital deafness, heterochromia irides, synophrys, broad nasal root, and dystopia canthorum

72
Q

What gene is involved in Waardenburg syndrome type I?

A

PAX3

73
Q

What are the clinical features of Waardenburg syndrome type I?

A

White forelock (20%–60%), synophrys, heterochromia irides, dystopia canthorum (eyes appear widely spaced due to lateral displacement of inner canthi; interpupillary distance is normal), and deafness (20%–40%)

74
Q

What are the genes and inheritance pattern in Waardenburg syndrome type II?

A

MITF = AD

SNAI2 = AR

75
Q

Clinical features in Waardenburg syndrome type II?

A

LIke WS1 but no dystopia canthorum and deafness is MORE common

76
Q

What gene is involved and what is the inheritance pattern in Waardenburg syndrome type III?

A

PAX3

AD

77
Q

Clinical appearance in Waardenburg syndrome type III?

A

Similar to type I but there are also upper limb abnormalities (hypoplasia, contractures, and syndactyly)

78
Q

What are the genes involved and the inheritance pattern in Waardenburg syndrome type IV?

A

EDNRB = AD, AR

EDN3 = AD, AR

SOX10 = AD

79
Q

Clinical appearance in Waardenburg syndrome type IV?

A

Similar to WS1 + Hirschsprung’s disease

80
Q

What is the gene and the inheritance pattern in McCune-Albright syndrome?

A

GNAS1

  • Non-inherited postzygotic somatic activating mutations in the gene
81
Q

What is the gender predilection in McCune-Albright syndrome?

A

Females >> Males

82
Q

What is the triad of clinical findings in McCune-Albright syndrome?

A

Café au lait macules (CALM), polyostotic fibrous dysplasia, and endocrine dysfunction

83
Q

What is the typical appearence of the CALM’s in McCune-Albright syndrome?

A

“Coast of Maine” appearance i.e. jagged borders and segmental

84
Q

Where do skeletal abnormalities in McCune-Albright syndrome usually occur?

A

The polyostotic fibrous dysplasia usually happens under the CALM’s

  • Sx’s include bone pain, gait abnormalities, visible skeletal deformity, and recurrent pathologic fractures
85
Q

What endocrinologic abnormalities can occur in McCune-Albright syndrome?

A

Precocious puberty, hyperthyroidism, acromegaly, infantile Cushing syndrome and hypophosphatemic rickets

86
Q

What is the affected gene and the mode of inheritance for Reticulate acropigmentation of Kitamura?

A

ADAM10

AD

87
Q

What is the clinical appearance of Reticulate acropigmentation of Kitamura?

A

Slightly depressed, lentigo-like hyperpigmented macules coalescing into a reticulated pattern on the dorsal hands and feet

  • Hyperpigmented macules can darken and the distribution may expand over time
  • Palmoplantar pits and abnormal dermatoglyphics can also be seen
88
Q

What is the histology of Reticulate acropigmentation of Kitamura?

A

Epidermal atrophy w/ elongated rete and increased melanin + increased number of melanocytes

89
Q

What is the gene and mode of inheritance for Dowling-Degos disease?

A

Rare, AD

Mutations in keratin 5 gene

90
Q

What other condition is associated w/ mutations in the keratin 5 gene?

A

Epidermolysis bullosa simplex w/ mottled pigmentation

91
Q

Clinical appearance of for Dowling-Degos disease?

A

Onset usually during adulthood

  • Presents w/ reticulated hyperpigmentation in the axilla and groin. Can also spread to gluteal and inframammary folds, neck, torso, inner thighs
  • Comedone-like lesions on the back or neck, pitted perioral scars, epidermoid cysts, and hidradenitis suppurativa have also been reported
92
Q

Histology of Dowling-Degos disease?

A

Increased pigmentation of the basal layer and “angler-like” pattern w/ finger-like rete ridges

  • Dermal melanophages and mild perivascular lymphohistiocytic infiltrate
93
Q

What is Galli-Galli disease?

A

It is a variant of Dowling-Degos disease that looks like DDD but has suprabasal acantholysis on histology

94
Q

What is dyschromatosis?

A

Both hypo and hyperpigmentation

95
Q

What is the gene and the mode of inheritance of Dyschromatosis symmetrica hereditaria (acropigmentation of Dohi)?

A

Heterozygous mutations in ADAR (SRAD) gene (RNA-specific adenosine deaminase)

  • AD
96
Q

Presentation of Dyschromatosis symmetrica hereditaria (acropigmentation of Dohi)?

A

Presents by 6 years of age

  • Patients have dyschromia and hyperpigmented/hypopigmented macules restricted to sun-exposed skin on dorsal aspects of extremities and face
97
Q

What is the gene and mode of inheritance for Dyschromatosis universalis hereditaria?

A

AD/AR

  • Mutations in ABCB6 (ATP-binding cassette subfamily B, member 6)
98
Q

Clinical presentation of Dyschromatosis universalis hereditaria?

A

Generalized or torso-predominant, well-demarcated brown macules interspersed with variously sized hypopigmented macules with a mottled appearance

  • Nail dystrophy and pterygium
  • Reports of associations with short stature, idiopathic torsion dystonia, X-linked ocular albinism, photosensitivity, and neurosensory hearing loss
99
Q

What is the most common form of inheritance for Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

XLR (can also be AD or AR)

100
Q

What are the gene mutations involved in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

Mutations in TERT, TERC ( AD); DKC1 (XLR), or TINF2

101
Q

What is the underlying pathology in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

The genes involved are involved in telomere maintenance –> patients have reduced telomerase activity and abnormally shortened telomeres –> chromosomal instability/cellular replication dysfunction

102
Q

Skin features in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

Triad: abnormal skin pigmentation, oral leukoplakia, and onychodystrophy

  • Can also see palmoplantar hyperkeratosis, hyperhidrosis, and diffuse non-scarring alopecia
103
Q

What is the distribution of the skin lesions often in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

Reticulated poikilodermatous patches of the face/neck/upper torso

104
Q

Is there an increased risk of malignancy in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

Yes –> Hematopoietic malignancies and squamous cell of the oral mucosa/anus/genitalia/esophagus/skin

105
Q

What is the primary cause of mortality in pts w/ Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

Bone marrow failure, pulmonary fibrosis, and malignancy (3rd adn 4th decade)

106
Q

What is the median age of death in Dyskeratosis congenita (Zinsser-Engman-Cole syndrome)?

A

16 y/o

107
Q

What is the gene and mode of inheritance for Naegeli-Franceschetti-Jadassohn Sydnrome (dermatophathia pigmentosa reticularis)?

A

AD

Keratin 14 (NFJS and DPR are allelic ectodermal dysplasia disorders that share many features)

108
Q

Clinical appearance of Naegeli-Franceschetti-Jadassohn Syndrome?

A

Brown-Gray reticulated hyperpigmentation typically on the abdomen, develops in early childhood (2 y/o), and improves after puberty

  • Can also see palmoplantar keratoderma, adermatoglyphia, onychodystrophy, hypohidrosis, and dental anomalies including early loss of teeth
109
Q

What is the clinical presentation of Dermatophathia pigmentosa reticularis?

A

Diffuse non-scarring alopecia, onychodystrophy, adermatoglyphia, and diffuse, persistent reticulated hyperpigmentation of the torseo and proximal extremities

DERM (09) Genodermatoses (13 decks)

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