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Benign melanocytic neoplasms Flashcards

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Dermatology Board Prep flashcards
1
Q

Pathogenesis of ephiledes

A

Sun-induced melanogenesis and transport of an increased number of fully melanized melanosomes from melanocytes to keratinocytes

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2
Q

Ephilede histo

A
  • Epidermis: normal
  • Keratinocytes: increase in melanin content predominantly in the basal cell layer
  • Can see melanophages in the papillary dermis
  • Density of melanocytes doesn’t change, but they are larger and have more branching of dendrites, and a higher DOPA positivity –> so have greater functional activity
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3
Q

Ephilede on dermoscopy

A

Uniform pigmentation and a moth-eaten edge

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4
Q

Solar lentigo on dermoscopy

A

Diffuse light brown structureless areas
Sharply demarcated and/or moth eaten borders
Fingerprinting
Reticular pattern with thin lines that are occasionally short and interrupted

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5
Q

What % of the population has a CALM

A

10-20%

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6
Q

What is the pathogenesis of a CALM

A

Increased melanogenesis and increase in melanin content within keratinocytes results in hyperpigmentation

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7
Q

Dermoscopy of a CALM

A

homogenous brown patch with peri-follicular hypopigmentation, +/- faint reticular pattern

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8
Q

CALM histopath

A
  • Normally configured epidermis
  • Slightly increased melanin content in basilar keratinocytes
  • Adnexal epithelium is spared of hyperpigmentation
  • Melanophages are rarely found in the dermis
  • Isolated lesions - melanocytic density is actually less than surrounding skin
  • DOPA-stained epidermis from NF1: higher density of melanocytes in both CALMS and normal adjacent skin
  • Melanin macroglobules - large pigment particles result from fusion of autophagosomes contain varying numbers of melanosomes –> not specific for NF1 though as occasionally found in isolated CALMs, and occur in simple lentigines, Becker melanosis, congenital melanocytic naevi, normal skin
  • Electron microscopy: melanosomes are usually dispersed singly within melanoyctes, and are usually homogenous, electron-dense and ellipsoidal when fully melanized
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9
Q

What is a cafe noir spot

A

hyperpigmented patches that have an even darker hue than CALMs and are seen in LEOPARD syndrome and the Carney complex

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10
Q

Becker melanosis epidemiology

A
  • Usually acquired, some are congenital
  • Most often appear during the second and third decades of life
  • 6X more common in males than females
  • Familial occurrence has been reported
  • Prevalence in 17-26 year olds was 0.5%
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11
Q

Becker melanosis pathogenesis

A
  • Unclear
  • Organoid hamartoma of ectodermally and mesodermally derived tissues
  • Androgen:
    • Heightened sensitivity to androgens
    • Explains onset in puberty
    • Explains hypertrichosis, dermal thickening, acne and hypertrophic sebaceous glands
    • Could also explain the accentuated smooth muscle elements often found in the dermis
  • Recently post-zygotic mutations in beta-actin were reported to be associated with Becker naevus and Becker naevus syndrome
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12
Q

Becker naevus syndrome

A

Developmental anomaliges that are generally hypoplastic in nature have been associated -

  • Hypoplasia of ipsilateral breast, areola, nipple, arm
  • Ipsilateral arm shortening
  • Lumbar spina bifida
  • Accessory scrotum
  • Supernumerary nipples
  • For this syndrome, the male female ratio is reversed 2:5
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13
Q

Clinical features of Becker naevus

A
  • Second or third decade
  • Sometimes following intense sun exposure
  • Most often unilateral
  • Usually involve and upper quadrant of the anterior or posterior chest
  • Have also been described on the face, neck, lower trunk, extremities and buttocks
  • Normally appear as a single lesion, but multiple lesions have occasionally been observed
  • Diameter ranges from a few cm to >15 cm
  • Most common configuration: block-like, although linear has been reported
  • Hyperpigmentation: uniformly tan to dark brown, with centre having slight thickening and corrugation of the skin
  • Well demarcated, but margins irregular
  • After hyperpigmentation, hypertrichosis develops and the hairs become coarser and darker with time (sometimes can be really subtle and can only tell when compare to contralateral side)
  • Hypertrichosis and hyperpigmentation may not overlap completely
  • After initial appearance, may enlarge slowly for a year or 2, then remains stable in size
  • Colour can fade but hypertrichosis persists
  • Asymptomatic, some report pruritus
  • Firmness to palpation - associated smooth muscle hamartoma
  • Some patients:
    • peri-follicular papules may be a sign of coexistent proliferation of arrector pili muscle
    • acneiform lesions limited to the area of hyperpigmentation
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14
Q

Becker naevus pathology

A
  • Epidermis: variable degree of acanthosis, hyperkeratosis and sometimes mild papillomatosis
  • Regular elongation of the rete ridges, hyperplasia of the pilosebaceous unit may be seen
  • Melanin content of the keratinocytes is increased
  • Number of melanocytes is normal or only slightly increased, without nesting
  • Melanophages may be seen in the papillary dermis
  • Concomitant smooth muscle hamartoma is often present too
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15
Q

Lentigo simplex pathogenesis

A
  • Increased number of melanocytes within the basal layer of the epidermis leads to increased production of melanin, resulting in hyperpigmented macules
  • Some penile lesions follow: injury, irritation, PUVA
  • Women: hormonal factors thought to play a role
  • Acral: genetics, since darker pigmented individuals
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16
Q

Lentigo simplex epidemiology

A
  • Frequency unknown
  • Found in all races
  • M=F
  • Can be present at birth in darker skinned newborns
  • Can increase in number during childhood or puberty
  • Lentiginosis: eruptive form
  • After melanocyte activation, lentigo simplex represents the next most common histology in matrix biopsies of longitudinal melanonychia
  • In darker pigmented individuals, lentigo simplex is the most common histologic pattern for cutaneous pigmented lesions in acral sites
  • Lentigo simplex occasionally develops within scars following excision of cutaneous melanoma, as do solar lentigines (present as pigmented streaks due to basilar hyperpigmentation)
17
Q

Oral melanotic macules epidemiology

A
  • Primarily in adults >40 years of age
  • Slight female predilection, but others report M=F
  • Most common site: vermilion border, followed by gingiva, buccal mucosa and palate
  • Up to 30% of melanomas in the oral cavity of Caucasians are preceded by melanosis for several months or years
    • Japanese: 2/3 of infiltrative oral melanomes arise in association with oral melanosis
  • Labial melanotic macule: usually appears between the second and fourth decades of life, and has a strong predilection for Caucasian women
18
Q

Genital melanosis epidemiology

A

Lentiginosis in the female genital area

  • Probably higher than reports
  • Most lesions found on labia minora, but can occur on labia majora, vaginal introitus, cervix, periurethral area, perineum as well as perianally
  • Generally benign, atypia is uncommon and progression to melanoma has been rarely observed

In the male genital area:

  • ?14% but don’t know what they were
  • Occur on glans penis and penile shaft, and peri-anally
19
Q

Conjunctival melanosis with relationship to melanoma

A
  • incidence is unknown
  • assumed that primary acquired melanosis is a precursor lesion of melanoma, since a significant number of conjunctival melanomas are associated with it
20
Q

Dermoscopy of mucosal lentigines

A

mucosal lentigines have a fingerprint pattern with narrow parallel lines, and broader track-like pigmentation interrupted by dots and globules

21
Q

Lentigo simplex clinical

A
  • Light brown to black, homogenously pigmented macules occurring anywhere on the body - including MM and palmoplantar skin
  • No predilection for sun-exposed areas
  • Well circumscribed, round or oval, have regular borders and are usually <5 mm (often <3mm) in diameter)
  • Lesions on the mucous membranes frequently have irregular, ill-defined borders as well as mottled non-homogenous pigmentation with areas devoid of pigment –> may resemble early melanoma
  • Lentigo simplex: solitary or multiple
  • Generalized: can be an isolated phenomenon, either present at birth of appearing later, or may be a sign of a genetic disorder
  • Mucous membrane lesions can slowly increase in size over months to years, with or without changes in degree of pigment (unlike skin ones)
  • Relationship between acral or anogenital lentigines and acrolentiginous melanoma requires more investigation
22
Q

Generalized lentigines ddx

A

Ligated PC

LEOPARD syndrome
Generalized lentigines
Arterial dissection plus lentiginosis
Tay syndrome
Deafness plus lentiginosis

Pipkin syndrome
Carney syndrome

23
Q

Localized lentigines

A

CCCCLIPP

Cowden
Cantu
Centrofacial lentiginosis
Crohnkhite-Canada syndrome
Laugier Hunziker
Inherited pattern lentiginosis
Peutz Jehger
Partial unilateral lentiginosis
24
Q

Leopard sx

A

AD - high penetrance, variable exprressivity
Mutations PTPN11 >RAF1 >BRAF

Now referred to as Noonan syndrome with multiple lenitigines
Lentigines, ECG conduction defects, ocular hypertelorism, pulmonary stenosis, abnormalities of genitalia, retardation of growth, deafness

Multiple lentigines are present at birth, or appear during early infancy and may increase in number during childhood
Generalized: sun exposed and protected sites - genitalia, palms, soles

25
Q

Carney complex

A 
AD inheritance
Mutations in PRKAR1A
Cutaneous: lentigines, mucocutnaeous myxomas, blue naevi (including epithelioid)
Psammomatous melanotic schwannomas
Axtrial myxoma
Myxoid mammary fibroadenomas
Pigmented nodular adrenocortical disease
Testicular - calcifying Sertoli cell, thyroid and pituitary tumours (pdces growth hormone)

How to remember: NAME/LAMB
Naevi, atrial myxoma, myxoid neurofibromas, ephelides
Lentigines, atrial myxoma, mucocutaneous myxomas, blue naevi

26
Q

Partial unilateral lentiginosis

A

Multiple lentigines in a segmental distribution
CALM in same
Suggests a developmental abnormality of melanocytes
Onset during childhood
Well circumscribed, vary from 2-10 mm
No background hyperpigmentation
Lesion can expand in a wavefront like manner
Can have ocular involvement if involves face
May be associated with mosaic NF1

27
Q

Lentigo simplex pathology

A
  • Increased number of melanocytes in the basal layer of elongated epidermal rete ridges
  • Increased melanin in the basal layer and sometimes in the upper layers of the epidermis and SC is commonly observed
  • Melanophages and mild inflammatory infiltrate are often present in the superficial dermis
  • Mucous membranes:
    • Acanthosis +/- elongation of the rete ridges
    • Slight melanocytic hyperplasia
    • Labial can have hyperkeratosis, telangiectasia, activated fibroblasts, large dendritic melanocytes
    • Some acrial and mucosal lesions have been reported to exhibit cytologic atypia
  • Ultrastructurally: melanin macroglobules have been observed within melanocytes, as well as in keratinocytes and melanophages (not specific for lentigo simplex)
28
Q

Dermal Melanocytosis epidemiology

A
  • Present at birth or first few weeks of life
  • M=F
  • Regresses during early childhood, but can persist - in Japanese population persistence by ~ 4%
  • Occurs in all races, but perhaps more common in Asian countries
  • Genetic factors influence survival of dermal melanocytes
  • Microscopically, histologic findings can be found in the presacral area of 100% of newborns regardless of race!
29
Q

Dermal melanocytosis pathogenesis

A
  • Melanocytes in the mid to lower dermis produce melanin which looks blue
  • Melanocytes appear in the dermis in the 10th week of gestation, and then either migrate to the epidermis or undergo cell death, EXCEPT for the melanocytes in the dermis of the scalp, extensor aspects of the distal extremities and the sacral area
  • The sacral area is the most common spot for dermal melanocytosis
  • Bluish colour is from the Tyndall phenomenon: dermal pigmentation appears blue because of decreased reflectance of light in the longer-wavelength region compared with the surrounding skin - longer wavelengths such as red, orange and yellow are not reflected compared with short wavelengths of blue and violet
30
Q

Dermal melanocytosis clinical

A
  • Sacrococcygeal and lumbar regions and buttocks, followed by back
  • Single or multiple patches, usually involves <5% of the BSA
  • Macular, and have a round, oval or angulated shape
  • Size varies from a few to more than 20 cm
  • Colour varies from light blue to dark blue to blue-gray
  • Extra-sacral:
    • Tend to be more persistent
    • Overlaps between persistent lesions and entitities adult onset dermal melanoyctoses, naevus of Ito and patch blue naevus
  • Extensive DM:
    • Phakomatosis cesioflammea - type 2 PPV
    • Phakomatosis cesiomarmorata - type V PPV
  • When CALMS and congenital melanocytic naevi reside within areas of dermal melanocytosis, there may be a rim that lacks dermal melanocytes around each lesion
31
Q

Dermal melanocytosis pathology

A
  • Bipolar dendritic melanocytes are dispersed singly in the lower half or lower 2/3 of the dermis
  • Melanocytes are DOPA-plsitive, and lie parallel to the epidermis between collagen bundles without disturbing the normal architecture of the skin
  • Occasionally, it may look like a blue naevus with involvement of the subcutis, muscle and fascia by melanocytes
  • Electron microscopy: melanocytosis shows fully developed melanocytes with exclusively mature, electron-dense melanosomes and very few premelanosomes
32
Q

Dermal melanocytosis ddx

A
  • Naevus of Ota - if facial invovlement
  • Naevus of Ito
  • Patch blue naevus - has multiple names including dermal melanocyte hamaroma, acquired DM –> clearly there is overlap with the rare adult onset dermal melanocytosis
  • Venous malforamtions
  • Deep IH
  • Contusion

Derm (57 decks)

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