Pigmentary disorders

Question 1

DDx

Answer 1

Description: Grey- brown reitculated pigmentation along the lines of blackcho in an small child

Dx: Stage 3 Incontinentia Pigmenti

DDx:
- Linear / whorled nevoid hypermelanosis
- X-linked reticulate pigmentary disorder

Question 2

Question 3

Answer 3

Swirls and streaks of brown pigmentaiton on the trunk - blashkoid distribution

Dx; Linear and whorled nevoid hypermelanosis

DDx:
- Stage 3 incontinentia Pigmenti
- Early epidermal naevus
- X linke reticulate pigmentory disorder

Question 4

Answer 4

Linear cris-cross streaks of brown pigmentation on the back - consistent with flagellate pigmentation

Dx:
- bleomycin induced pigmentation (normally with cumulative doses of 100 - 300 mg)

DDx:
- shitake dermatitis
- Dermatomyositis
- Post inflammatory hyperpigmentation
- persistent plaques of stills disease

Question 5

Answer 5

Bilateral and symmetrical - well demarcated lines of relatively hyperpigmented skin laterally and hypopigmented skin medially

Dx: Classic of pigmentary dermarcation lines

Question 6

Answer 6

Parallel line of relatively hypopigmented skin (centrally) and hyperpigmented skin (laterally) - consistent with a pigmentary hyperpigmentation line

Question 7

Answer 7

Blue grey pigmentation on the shins and dorsal feet

Dx Drug induced (hydroxychloroquine) pigmentation

Question 8

Answer 8

Unilateral - block like - light brown pigmentaion on the chest, abdomen and upper arm of an infant with midline demarcation

Segmental pigmentation / pigmentary mosacism

Question 9

Answer 9

Dark, slate grey pimgentation of the bilateral hands

Consisent with Argyria = silver

Question 10

Answer 10

Brown reticular pigmentation on the upper chest and upper back

Dx: confluent reticular papilomatosis

DDx:
- erythema ab igne
- Pruigo pigmentosa
- Dermatopathia pigmentosa reticularis

Question 11

Answer 11

Reticulated light brown hyperpigmentaiton on the trunk and thigh

Dx: dermatopathia pigmentosa reticularis

Question 12

Answer 12

Hyperpigmented macues forming a reticulated pattern in the axillae

Question 13

Answer 13

Diffuse mixed guttate hyper and hypo pigmentation of the lower legs

Dx; Dyschromic amyloidosis cutis
DDx: dyschrmoatosis symmetrica hereditaria, dyschromatosis universalis hereditaria

Question 14

Answer 14

Mixed hyper and hypopigmentation of the upper limbs

Dx dyschrmoatosis symmetrica hereditaria

Question 15

Question 16

Answer 16

Light brown macular pigmentation on the cheek with irregular well demarcated border

Dx; Melasma

DDx; PIH, Lichen planus Pigmentosa

Question 17

Answer 17

Linear hyperpigmentation on the forearm

Dx: phytophotodermatoses

Question 18

Answer 18

Whorled and liner hyperpigmentation on the trunk - following lines of blaschko

Dx: linear and whorled naeviod hypermelanosis

Question 19

Answer 19

Light brown hyperpigmented streaks along the lines of Blaschko

Dx: linear and whorled nevoid hypermelanosis, conradi hunermann happle syndrome, stage 3 Incontinentia pigmenti

Question 20

Answer 20

Reticulated hyperpigmentation on the lower back

Consistent with erythem ab igne

Question 21

What is dyschromatosis symmetrica hereditaria?

Answer 21

An autosomal dominant condition

characterized by both hyper- and hypopigmented
macules of varying size on the dorsal surfaces of the distal extremities.

Caused by a defect by heterozygous mutations in ADAR which encodes the RNA-specific adenosine deaminase

Question 22

What gene and inheritance is involved in dyschromatosis symmetrica hereditaria?

Answer 22

Heterzygotic mutaiton in ADAR

Autosomal dominant

Question 23

Which features distinguish erythema dyschromicum perstans (EDP) from lichen planus pigmentosus (LPP) clinically and histologically?

Answer 23

Erythema Dyschromicum Perstans (EDP):

Clinical:
* Slate-gray to blue–brown macules/patches, often symmetric.
* Predominantly on trunk, neck, proximal limbs.
* May have a faint erythematous border in early lesions (fades).

Histopathology:
* Pigment incontinence with numerous dermal melanophages.
* Minimal or absent inflammation in late lesions.
* Basal vacuolar change may be present early, but less pronounced than LPP.

Lichen Planus Pigmentosus (LPP):
Clinical:
* Brown to gray–brown macules, often in photodistributed or intertriginous areas (e.g. forehead, temples, neck).
* No erythematous border.
* Often more diffuse or reticulated in pattern.

Histopathology:
* Lichenoid interface dermatitis: basal cell vacuolar degeneration, colloid bodies, and band-like lymphocytic infiltrate.
* Pigment incontinence with dermal melanophages.

Question 24

What gene mutation is ass with Dowling Degos disease and what is the clinical distribution

Answer 24

Gene: AD defect in Keratin 5

Clinical
- Reticulate hyperpigmentation in the flexures
- Comedonal / follicular papules
- Pitted scars (esp perioral)

Can overlap with Hidradenitis supurativa

Question 25

What are the distinguishing clinical features and mutation seen in **reticulate acropigmentation of Kitamura (RAK)?**

Answer 25

Gene: ADAM 10 Starts as lentigo like macule on the acral surfaces, progressing to more reticulate hyperpigmentation Ass with palmar pits Absent dermatoglyphics

Question 26

Which dermatosis is most likely to show a history of previous vesicular or verrucous skin stages before the development of reticulated hyperpigmentation along Blaschko’s lines?

Answer 26

Incontinentia Pigmenti

Question 27

What is the inheritance of incontinentia Pigmenti?

Answer 27

X- Linked Often lethal in males. Has 4 stages: - vesicular - verrucous - Hyperpigmented - hypopigmented / atrophic

Question 28

Which pigmentary disorder is associated with dental anomalies, heat intolerance due to hypohidrosis, palmoplantar keratoderma, and reticulated hyperpigmentation that often fades after puberty?

Answer 28

Naegeli–Franceschetti–Jadassohn Syndrome (NFJ) Genetic, AD condition, Keratin 14 defect

Question 29

Which condition is caused by mutations in POLA1, presents with reticulated hyperpigmentation generalized in males and Blaschkoid in females, and is associated with systemic inflammatory features in boys?

Answer 29

X Linked Reticulate pigmentary disorder

Question 30

Treatment options for melasma?

Answer 30

Question 31

Which pigmentary disorder presents in childhood with persistent reticulated hyperpigmentation of the trunk, non-scarring alopecia, nail dystrophy, and is caused by KRT14 mutations?

Answer 31

Dermatopathia Pigmentosa Reticularis (DPR)

Question 32

Which genodermatosis features reticulated hyperpigmentation, dental anomalies, hypohidrosis, nail changes, and loss of dermatoglyphics, but lacks alopecia and bone marrow failure?

Answer 32

Naegeli–Franceschetti–Jadassohn (NFJ) Syndrome Key Clinical Features: Reticulated hyperpigmentation (onset <2 years; fades in adolescence) Dental anomalies (e.g. conical/supernumerary teeth, early tooth loss) Hypohidrosis → heat intolerance Palmoplantar keratoderma Onychodystrophy Absent or hypoplastic dermatoglyphics

Question 33

Which disorder involves early-onset reticulated pigmentation, bone marrow failure, leukoplakia, and is caused by telomere maintenance defects?

Answer 33

Dyskeratosis Congenita

Question 34

What are the three classic facial distribution patterns of melasma?

Answer 34

Centrofacial – involves the forehead, cheeks, upper lip, nose, and chin (most common) Malar – affects the cheeks and nose Mandibular – along the jawline

Question 35

Which skin phototypes are most commonly affected by lichen planus pigmentosus (LPP)?

Answer 35

III - V

Question 36

What medication is most classically associated with flagellate hyperpigmentation?

Answer 36

Bleomycin - presenting as linear, whip-like streaks, typically on the trunk, and often exacerbated by minor trauma (Koebner phenomenon).

Question 37

What are Pigmentary Demarcation Lines (PDLs), and where is Type A most commonly seen?

Answer 37

Pigmentary Demarcation Lines (PDLs) are physiologic lines that mark the boundary between darker dorsal skin and lighter ventral skin, Type A PDL is most commonly seen along the anterolateral upper arm, sometimes extending into the pectoralis region.

Question 38

Acquired causes of hyperpigmentation (generalised) in an adult

Answer 38

Hyperthyroidism Haemochromatosis Addisons disease Ectopic ACTH production Congenital adrenal hypoplasia Drug induced (hydroxyquinolone, minocycline, etc)

Question 39

List some common triggers for linear PIH?

Answer 39

Phytophotodermatitis – from exposure to furocoumarin-containing plants + UV (e.g. lime juice, celery, fig sap) Linear lichen planus – follows lines of Blaschko Flagellate dermatitis – from bleomycin or shiitake mushrooms Excoriations or trauma – especially in psychogenic excoriation Black lacquer from poison ivy – leaves jet-black linear marks

Question 40

Which topical combination therapy is considered first-line for treating melasma?

Answer 40

The first-line topical combination therapy for melasma is: 👉**Hydroquinone + Retinoid (e.g. tretinoin) + Topical corticosteroid** This is often referred to as "triple therapy", and typically consists of: **Hydroquinone 4%** – inhibits tyrosinase, reducing melanin synthesis **Tretinoin 0.05–0.1%** – increases epidermal turnover **Mild corticosteroid (e.g. fluocinolone acetonide 0.01%)** – reduces inflammation and irritation

Question 41

Which endocrine disorder is classically associated with diffuse hyperpigmentation, especially involving the palmar creases, mucosa, and sun-exposed areas?

Answer 41

Addison’s disease (primary adrenal insufficiency) leads to increased ACTH, which shares a precursor (POMC) with melanocyte-stimulating hormone (MSH) — stimulating melanogenesis. Hence, diffuse hyperpigmentation especially in: Palmar creases Buccal mucosa Pressure points and sun-exposed areas

Question 42

Name two nutritional deficiencies that can cause diffuse hyperpigmentation.

Answer 42

**Pellagra** – due to niacin (vitamin B3) deficiency * Hyperpigmentation in sun-exposed areas, often with a photosensitive rash * Remember the 4 D’s: Dermatitis, Diarrhea, Dementia, Death **Vitamin B12 deficiency** * Causes diffuse or patchy hyperpigmentation, especially on dorsal hands, feet, and mucosa * Thought to relate to melanin synthesis disruption via homocysteine elevation and oxidative stress

Question 43

Which systemic disease causes diffuse hyperpigmentation with skin induration and may mimic scleroderma?

Answer 43

👉 **POEMS Syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy, and Skin changes)** Skin findings in POEMS include: * Diffuse hyperpigmentation * Sclerodermoid thickening * Hypertrichosis * Hemangiomas Systemic sclerosis itself can also cause hyperpigmentation, especially along areas of sclerosis, but POEMS is a classic paraneoplastic syndrome to keep in mind.

Question 44

Which type of renal failure–associated pigmentary change causes diffuse hyperpigmentation, and what is its proposed mechanism?

Answer 44

In chronic renal failure, patients can develop diffuse hyperpigmentation, especially in sun-exposed areas (e.g. face, hands). Proposed Mechanism: Retention of β-melanocyte stimulating hormone (β-MSH): Normally cleared by the kidneys Stimulates melanogenesis Uremic toxins may also indirectly increase melanin synthesis Sometimes accompanied by yellowish skin hue due to carotenoid accumulation

Question 45

In which diffuse hyperpigmentation disorder would you find "raindrop" pattern dyspigmentation, and what toxic exposure is responsible?

Answer 45

Arsenic