Acquired Hypomelanosis Flashcards
Acquired Localised hypo or depigmentation DDx
Woods light exam
PRIMARY DEPIGMENTATION (no inflammation)
Vitiligo
Halo naevus
Melanoma-assoc leukoderma
PRIMARY HYPOPIGMENTATION (no inflammation)
Idiopathic guttate hypomelanosis
Localised congenital hypomelanoses
Progressive macular hypomelanosis —> orange red fluorescence on woods light (P. acnes)
SECONDARY HYPOPIGMENTATION (post infectious, post-inflammatory, post-traumatic)
Infection -
Pityriasis versicolor —> yellow green fluorescence on woods light (malessezia)
Leprosy
Syphilis
Inflammatory - Pityriasis alba Psoriasis Sarcoidosis Pityriasis lichenoides chronica Lichen striatus Lichen planus Lichen sclerosus Lupus erythematosus Scleroderma/morphoea
Malignant -
MF
Post-traumatic -
Chemical and physical agents
Punctate leukoderma (from PUVA or nbUVB)
NON-MELANOTIC LEUKODERMA Bier’s spots Woronoff’s ring (psoriasis) Cutaneous oedema Naevus anemicus
Acquired Diffuse hypo or depigmentation DDx
Wood’s light exam
DEPIGMENTATION
Vitiligo
HYPOPIGMENTATION Endocrinopathies Nutritional and metabolic disorders Chemical agents Post-inflammatory Haemodialysis
NON-MELANOTIC LEUKODERMA
Anaemia
Vitiligo
Acquired Localised depigmentation
Progressive loss of melanocytes
CLINICAL FEATURES
Milky white sharply demarcated macules
Macules have convex outline
Macules increase irregularly in size and fuse with neighbouring lesions
Margins can be hyperpigmented
Areas of repeated friction, chronic pressure/trauma
- Hips
- Dorsal hands, fingers, feet
- Elbows, knees
- Ankles
Lesions prone to sunburn
Itch
Symmetrical distribution (except for segmental vitiligo —> unilateral and band-shaped)
Rarely vitiligo universalis (complete vitiligo)
Partial or complete pigment loss —> trichrome vitiligo if both occur im the same areas
Hairs within patches can remain normally pigmented or depigment after a period of time —> poliosis/leukotrichia
2 major forms —> Segmental vs non-segmental vitiligo
SEGMENTAL VITILIGO
Unilateral in segmental band-shaped distribution
More likely in children than adults
Starts earlier in life amd often stabilises within 1st year of onset
NON-SEGMENTAL VITILIGO
Bilateral
Often in acrofacial pattern
Scattered symmetrically over entire body
UNCLASSIFIED/UNDETERMINED VITILIGO
Focal small macules not segmentally distributed and have not evolved into non-segmental vitiligo after 1-2 years
Isolated mucosal lesions
CLINICAL VARIANTS
Mixed vitiligo
Hypochromic vitiligo
Halo naevi associated leukoderma
MIXED VITILIGO
Coexistence of non-segmental and segmental vitiligo
HYPOCHROMIC VITILIGO
Limited to dark skinned ppl
Partial defect in pigmentation —> histo supportive of vitiligo
Repeated bx may be needed to exclude hypopigmented CTCL as a DDx
HALO NAEVI ASSOC LEUKODERMA
Analogous to melanoma assoc leukoderma
Discrete areas of depigmentation develop in skin distant from the halo naevi esp in ppl with large numbers of halo naevi
Probably d/t temporary autoimmune process directly linked to halo phenomenon
Differs from classic vitiligo
Depigmented macules more limited, not as clearly demarcated, do not progress
DDX VITILIGO Halo naevi Naevus depigmentosus Naevus anaemicus Inherited hypomelanoses - Piebaldism - Waardenburg syndrome - Tuberous sclerosis - Hypomelanosis of Ito Progressive macular hypomelanosis Secondary hypomelanoses - Post-inflammatory hypomelanosis i.e. pityriasis alba, morphoea, lichen sclerosus - Post-traumatic hypomelanoses - Post-infectious hypomelanoses i.e. pityriasis versicolor, leprosy - Hypopigmented CTCL
ASSOCIATED DISEASES (autoimmune/autoinflammatory) Thyroid disease (hyperthyroidism and hypothyroidism) - strongest association Hypoparathyroidism Pernicious anaemia Addisons disease Diabetes Myasthenia gravis Halo naevus Alopecia areata Morphoea and lichen sclerosus Melanoma Vogt-Koyanagi-Harada syndrome —> vitiligo, premature greying of hair, uveitis, CNS involvement
GENETICS
Polygenic inheritance
Pisutive family Hx
ENVIRONMENTAL FACTORS
Koebner phenomenon —> development of lesions at sites of trauma to uninvolved skin
IX
Clinical dx
Woods light exam if any confusion with other hypomelanotic disorders
MX
Rx often unsatisfactory esp for acral lesions
cosmetic camouflage
Sunscreen
Explain risk of koebnerisationfrom everyday activities
Successful Rx is results of combination Rx
Topicals for 6 months -
- Potent TCS i.e. daily
- Topical calcineurin inhibitors i.e. pimecrolimus, tacrolimus BD (face and neck)
Phototherapy, stop if no repigmentation within 3 months -
- PUVA
- NbUVB
Surgical grafting for stable vitiligo i.e. segmental vitiligo (Transplant autologous melanocytes from normal pigmented area to affected depigmented skin)
- Tissue grafts
—> Full thickness punch grafts
—> Split thickness grafts
—> Suction blister grafts
Cellular grafts (slightly lower repigmentation than tissue grafts, but more suited for larger areas, better cosmetic results, less dverse events)
—> Cultured melanocytes
—> Cultured epithelial sheet grafts
—> Non-cultured epidermal cellular grafts
Depigmenting Rx for extensive vitiligo and inly few residual areas of pigmentation
- QS pigment laser i.e. ruby 694nm, alexandrite 755nm
- LN2
- Topical 20% monobenzylether of hydroquinone
HISTO
Lack of dopa-positive melanocytes in the basal layer epidermis
Loss of melanocytes
Active/inflammatory edge (where there is raised erythematous border) —> lymphocytes and histiocytes
COURSE/PROGNOSIS
Gradually progressive
Sometimes extends rapidly over several months —> quiescent for many years
Spontaneous repigmentation im sun-exposed areas —> perifollicular appearance
Halo naevus
Development of a halo of hypomelanosis around a central cutaneous tumour
Usually in young ppl
TUMOUR TYPES Benign melanocytic naevus (usually) Neuroid naevus Blue naevus Neurofibroma Primary melanoma Melanoma met
CLINICAL FEATURES
Circular areas of hypomelanosis around pigmented naevi
Trunk > head > limbs
Multiple lesions common
Halos develop simultaneously or at intervals around several (but not all) naevi
TRIGGERS
Usually none
Sun exposure
Sunburn
ASSOCIATED DISEASES
Personal pr family Hx of vitiligo
Cutaneous melanoma
Turner syndrome ? Growth hormone therapy played a role
DDX
Vitiligo
CLINICAL VARIANTS
Hypomelanotic halo around melanoma
IX
Excision may be indicated in case there is doubt about the pigmented lesions’s benign character
HISTO
Mostly compound naevi
Junctional/dermal naevi possible
Both congenital and acquired naevi can be affected
Naevus —> Lymphocytic infiltration of the naevus —> damage to constituent cells
Depigmented halo —> absence of melanocytes +/- melanophages in the dermis
MX
Usually none
Mindful that halo around benign naevus is common, melanoma is rare, halo around melanoma is extremely rare —> never perform mutilating surgery withiut preliminary histo exam by experienced pathologist
COMPLICATIONS/CO-MORBIDITIES
Can be present +/- vitiligo
COURSE/PROGNOSIS
Naevus tends to flatten —> may disappear completely
Depigmented area often persists, but may repigment after years
Acquired syndromic hypomelanosis - Vogt-Koyanagi-Harada syndrome
CLINICAL FEATURES
Mainly affects dark skinned ppl Or whites with dark pigmentation
Adults 3rd/4th decades, children may be affected
Skin
- Vitiligo
- Poliosis
- Alopecia
Eyes
- Bilateral involvement
- Diffuse choroiditis (early sign)
- Ocular depigmentation (late sign)
Inner ears
- Tinnitus
CNS (meninges) -
- Meningismus
- CSF pleocytosis
No history of eye trauma or surgery preceding initial onset of uveitis
No clinical or lab evidence suggestive of ocular disease entities
Usually presents to ophthal with uveitis before onset of other symptoms
AETIOLOGY
Yet to be established
? Abnormal response to a virus —> immunological mechanisms
HISTO depigmented skin
Absence of melanocytes (as in vitiligo)
Colloid-amyloid bodies at DEJ
Acquired syndromic hypomelanosis - Alezzandrini syndrome
Similar to Vogt-Koyanagi-Harada syndrome (but Alezzandrini has no CNS features and unilateral eye involvement)
CLINICAL FEATURES
Skin
- Unilateral facial vitiligo
- Poliosis
Eyes
- Unilateral retinal detachment
Ears
- Deafness
AETIOLOGY
Unknown
Acquired secondary hypo or depigmentation - Chemical depigmentation
CLINICAL FEATURES
Dorsa hamds most commonly affected in occupational leukoderma
Depigmented reas frequently enlarge
New ones appear even after patient no longer in contact
Areas may or may not repigment —> almost complete absence of melanocytes
CAUSES OCCUPATIONAL LEUKODERMA
Phenols i.e. p-tert butylphenol ***
4-tert butylcatechol
Monobenzylether of hydroquinone (occupational, also used as Rx of diffuse hypomelanosis as a depigmenting agent) —> confetti-like areas in Rx areas
Acquired secondary hypo or depigmentation - punctate leukoderma
Young adults
Japan, Brazil
CLINICAL FEATURES
Multiple round or oval small sharply demarcated punctate macules
Symmetrically on anterior shins, extensor arms
+/- abdomen
+/- interscapular region
Macules not related to hair follicles
CAUSE Phototoxicity damage to keratinocytes and melanocytes - PUVA - NbUVB - sun exposure
DDX
Idiopathic guttate hypomelanosis (punctate leukoderma macules are smaller and repigmentation may occur)
HISTO
Slight to severe damage of keratinocytes and melanocytes (this is not present in idiopathic guttate hypomelanosis)
COURSE/PROGNOSIS
Persistent
Spontaneous repigmentation possible (unlike idiopathic guttate hypomelanosis)
Acquired primary hypo or depigmentation - Idiopathic guttate hypomelanosis
CLINICAL FEATURES Porcelain white macules Sharp borders, angular, irregular Pretibial, forearms \+/- other chronic sun exposed sites i.e. face, neck, shoulders Increases in number with age
CAUSE
UV induced (controversial)
May just reflect normal ageing, photoageing
Solar damage in whites
HISTO Slight basket weave hyperkeratosis Epidermal atrophy Flattening of rete ridges Decrease in melanocytes, melanin Pigment granules irregularly distributed in epidermis
MX
Not usually required
Not usually succesful
TOPICALS
Retinoids
TCS
Tacrolimus
PHYSICAL
LN2
Dermabrasion (beware dark skin types)
SYSTEMICS
Retinoids
COURSE/PROGNOSIS
Number increases with age
No spontaneous repigmentation
Acquired primary hypo or depigmentation - Progressive macular hypomelanosis
Adolescents
Young adults
CLINICAL FEATURES
Ill defined nummular (discoid) non scaly macules
Mainly trunk
Areas rich in sebaceous glands
Lesions often converge in and around midline
+/- proximal extremities, head, neck
CAUSE
P. acnes
IX
Woods light exam —> orange-red fluorescence
MX
Topical 5% benzac wash
Topical 1% clindamycin lotion
+/- nbUVB or PUVA
COURSE/PROGNOSIS
Stable or slowly progressive over time
Spontaenous regression rare, but possible within a few years
