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Dermatology Board Prep flashcards
1
Q

Solar lentigo pathogenesis

A
  • epidermal hyperplasia, with variable proliferation of melanocytes
  • accumulation of melanin within keratinocytes
  • response to chronic UVR exposure
  • Somatic mutations in FGFR3 and PIK3CA
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2
Q

Dermoscopy of solar lentigo

A

Dermoscope: diffuse, light brown structureless area, sharply demarcated and/or moth eaten borders, finger printing, reticular pattern with thin lines

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3
Q

Clinical solar lentigo

A
  • pigmented macules, often multiple
  • sun exposed sites
  • Can have ‘ink spot’ –> jet black colour with stellate outline
  • Independant risk factor for melanoma
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4
Q

Solar lentigo histology

A
  • Epidermis: may be thinned, increased basal cell layer pigmetnation
  • Rete ridges: club shaped or bud-like extensions
  • DOPA-stained: melanocytes exhibit increased melanogenesis
  • Superficial dermis: contains melanophages
  • +/- peri-vascular lymphocytic infiltrate
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5
Q

DDx of Solar lentigo

A
  • Other benign: ephelid, macular, seb k, simple lentigo, junctional melanocytic naevus, large cell acanthoma
  • Malignant: pigmented AK, lentigo maligna, melanoma
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6
Q

6 histo types of seb ks

A
  1. Acanthotic
  2. Hyperkeratotic
  3. Reticulated
  4. Irritated
  5. Clonal
  6. Melanoacanthoma
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7
Q

Epidemiology of seb k

A
  • Autosomal dominant inheritance with incomplete penetrance

- Caucasion population

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8
Q

Pathogenesis of seb k

A
  • Sun exposure - supported by being seen more in tropical climates and sun exposed sites
  • Genetic: FGFR3 and PIK3CA have been demonstrated
  • Irritation: apoptosis within areas of squamous differentiation have been implicated as a cause of irritation
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9
Q

Clinical features of seb k

A
  • Multiple, pigmented, sharply marginated lesions
  • Features:
    • Keratotic plugging
    • Stuck on appearance
    • Overlying scale
    • ~1 cm in diameter
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10
Q

Associations of seb k

A
  • Pregnancy
  • Co-existing inflammatory dermatoses
  • Malignancy
  • -> Leser-Trelat
  • -> malignancy within - BCC most common, some believe in collision theory
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11
Q

Leser-Trelat sign - associations, pathogenesis

A

Eruptive seb ks

  • Associated with gastric and colonic adenocarcinoma, breast carcinoma and lymphoma
  • May have associated pruritis - 40%
  • Acanthosis nigricans - 20% of patients
  • Pathogenesis unknown: believed to be related to secretion of growth factor by the neoplasm which leads to epithelial hyperplasia
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12
Q

Overall histology of seb k

A
  • Varying degrees of hyperkeratosis, acanthosis, papillomatosis
  • Highly characteristic:
    • Horn pseudocysts
    • Base of SK lies on a flat horizontal plane - ‘string’ sign
    • Papillomatosis and hyperkeratosis - ‘church spires’
    • Papillary dermis unremarkable
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13
Q

Melanoacanthoma variant of seb k

A
  1. rare variant
  2. numerous basal clear cells that can look like MIS
  3. however negative staining for Melan-A, MART-1 and S100
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14
Q

Treatment of seb k

A
  • Cosmesis only

- Physical: destruction, curettage, shave excision, cryotherapy, electrodesiccation, laser (erbium Yag)

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15
Q

Lichenoid keratosis epidemiology

A
  • between 35 and 65 years of age
  • F>M
  • Caucasians
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16
Q

Lichenoid keratosis pathophysiology

A
  • Inflammation of benign lentigo, SK or AK
  • Mutations in ~50%: FGFR3, PIK3CA, RAS
  • Increased numbers of Langerhans cells in epidermis –> lends to theory taht perhaps there is an unidentified epidermal antigen that results in lymphocyte infiltration
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17
Q

Lichenoid keratosis clinical features

A
  • Pink to red brown, often scaly, papules
  • Closely resembles Bowens or BCC
  • Asymptomatic
  • Common sites: forearm, upper chest
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18
Q

Dermatoscope features of lichenoid keratosis

A
  • Light brown pseudonetworks due to residual solar lentigo
  • Overlapping pinkish areas due to lichenoid inflammation
  • Annular granular structures - early regressing stage
  • Blue-gray fine dots - late regressing stage
  • Blue-gray dots or globules - represent melanophages
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19
Q

Lichenoid keratosis - histologic findings

A
  • +/- parakeratosis
  • Lymphocytic and histiocytic lichen infiltrate
  • Basal vacuolar alteration
  • Colloid bodies
  • if really ++ can develop subepidermal split
  • Can sometimes mimic MF with Pautrier-like microabscesses and epidermotropism
  • can regress and be confused with melanoma
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20
Q

Clinical and histological differentials for LK

A
  • Clinically:
    • Bowens, AK, BCC, melanoma, amelanotic
    • Melanocytic naevus, irritated SK
  • Histologically:
    • lichenoid - LP, LE, drug
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21
Q

Definitions of naevus

A
  1. congenital lesion or lesion arising early in life
  2. benign tumour of melanocytes
  3. hamartoma
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22
Q

Definition of hamartoma

A

Benign malformation with an excess or deficiency of structural elements normally found in the affected area - i.e. epidermis, connective tissue, adnexa

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23
Q

Skin tag associations

A

Diabetes

Birt-Hogg Dube and Cowden

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24
Q

Skin tag histology

A

polypoid, loose-dense collagenous stroma and thin-walled blood vessels

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25
Q

Cutaneous angiofibroma clinical

A
  1. Fibrous papule
    1. Solitary, dome-shaped and shiny skin-coloured to red purples
    2. Dermoscopy: white colour
    3. Usually on nose
  2. Pearly penile papules
    1. Pearly, white, dome-shaped closely aggregated small papules on glans penis, commonly in multi-layered and circumferential manner on the corona
    2. more common in uncircumcised
  3. Multiple facial angiofibromas
    1. Seen in TS, multiple endocrine neoplasia type 1, Birt-Hogg-Dube, NF type 2
    2. usually distributed bilaterally on the cheeks, nasolabial folds, nose and chin
    3. if you see these - look for multiple ungual angiofibromas
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26
Q

Angiofibroma histology

A
  • Dome shaped
  • Dermal proliferation of plump or stellate fibroblasts in a collagenous stroma
  • Increase in the number of thin-walled, dilated blood vessels
  • Collagen fibres arranged in a concentric fashion around hair follicles and blood vessels (peri-follicular fibroma)
27
Q

Dermatofibroma aetiology

A
  • ?previous trauma
  • argued as to whether is neoplastic or reactive
  • Associations when eruptive: autoimmune, atopic dermatitis, HIV
28
Q

Dermatofibroma clinical

A
  • Favours the lower extremities
  • Commonly hyperpigmented
  • Dimple sign: pinching the lesion results in a downward movement
  • Dermoscopy shows a central white scar-like patch or white network, surrounded by delicate pigment network
  • There are so many variants
29
Q

Dermatofibroma histology

A
  • Hyperplastic epidermis
  • Nodular dermal proliferation of spindle-shaped fibroblasts and myofibroblasts arranged as short, intersecting fascicles
  • May be a component of mono or multi-nucleated histiocytes with vacuolated (xanthomatous) cytoplasm
  • Hallmark: peripheral ‘entrapped’ collagen bundles
  • Keloidal collagen bundles are seen at the periphery
  • May haemorrhage - explains haemosiderin deposition
  • Immunohistochemistry:
  • Positive for vimentin, factor 13a, stromelysin, muscle specific actin, CD68
  • Negative for CD34, may show this just at periphery but not homogenous
30
Q

Dermatofibroma immunohistochemistry

A

Positive for vimentin, factor 13a, stromelysin, muscle specific actin, CD68
- Negative for CD34,

31
Q

Dermatofibroma some histologic variants

A
  • Epithelioid fibrous histiocytoma - firm, sessile or polypoid papules or nodules. Monomorphous population of large, stellate and triangular epithelioid cells with eosinophilic cytoplasm. Dome shaped or polypoid dermal ndoules.
  • Lipidized fibrous histiocytoma - striking prediliction for lower extremity. Has large foam cells and interspersed siderophages.
  • Fibrous histiocytoma of the face - dermal/subcutaneous plaque. Predominance of distinct cellular fascicles & bundles of spindle shaped tumour cells + classic features of DF
  • Deep dermatofibroma - usually on trunk and proximal extremities. Like DF but deep extension - 70% verticle or horizontal, 30% well circumscribed with smooth deep margin
  • Aneurysmal fibrous histiocytoma - large size and nodular or dome shaped with rapid growth. Large blood filled spaces, rimmed by densley aggregated siderophages, extravasation of erythrocytes, large sheets of histiocytes and brown, Prussian blue-positive siderophages
  • Dermatofibroma with atypical cells - monster! - Middle aged adults, histo like DF but with atypical mono and multinucleated cells with large pleomorphic and hyperchromatic nuclei. Treat these with clinical caution. If super atypical then maybe should classify as low-grade superficial cutaneous sarcoma or atypical fibrohistiocytic tumour
  • Metastasizing dermatofibroma - so rare. Warning signs: large primary tumour, extension into subcutis with infiltrative peripheral borders, high proliferation rate (Ki67) and mitotic activity and multiple recurrences
32
Q

Dermatofibroma histologic differentials

A
  • Keloid
  • Scar
  • CT naevus
  • Dermatomyofibroma
  • DFSP –> this would be CD34 positive in its entirety
  • Nodular Kaposi
33
Q

Porokeratoses epidemiology

A
  • Autosomal dominant, many appear to be sporadic though
  • Porokeratosis of Mibelli affects M>F
  • DSAP F>M, Caucasians
  • PPPD - AD, M>F
34
Q

Porokeratoses pathogenesis

A
  • Disorder of keratinization
  • Genetics: multiple involved such as POROK1, PMVK and MVK
  • Some postulate is an expanding mutant clone of keratinocytes, and there is a dermal lymphocytic response
  • Triggers: UVR, immunosuppression
  • Less accepted theory that dermal lymphocytic infiltrate directed against epidermal antigen
35
Q

Types of porokeratoses and prognosis

A 
Porokeratosis of mibelli
DSAP
Linear porokeratosis
Punctate porokeratoses
PPPD
Ptychotropica porokeratosis
- Development of SCC within porokeratoses has been reported
- DSAP has lowest risk of malignant change
- Other uncommon: reticular, follicular
36
Q

Porokeratosis of Mibelli clinical

A
  1. Infancy-childhood
  2. Asymptomatic, small brown or skin coloured keratotic papule that enlargens over a period of years
  3. Sharply demarcated, keratotic thready border with longitudinal furrow
  4. Centre: hyper, hypo, atrophic or anhidrotic
  5. Extremities most frequently involves
37
Q

DSAP clinical

A
  1. Small asymptomatic or mildly pruritic keratotic, tan-brown to pink-red papules range from 3-10 mm in diameter –> expand radially and centre becomes atrophic
  2. Bilateral and symmetric distribution, can be widespread and clasically spares face
  3. Resembles and can coexist with actinic keratoses
  4. 3rd-4th decade of life
  5. Rare association with HCV and SLE
38
Q

PPPD clinical

A
  1. Childhood or adolescence
  2. Palms and soles are initially affected
  3. Smaller and less pronounced keratotic border
  4. pretty uncommon
39
Q

Linear porokeratosis clinical

A
  1. Infancy or childhood
  2. Follows lines of Blaschko
  3. Commonly extremities
40
Q

Ptychotropica porokeratosis clinical

A
  1. Pruritic, red to brown papules and plaques in the intergluteal cleft and on the buttocks
  2. Multiple cornoid lamellae
41
Q

Punctate porokeratosis clinical

A
  1. appears during adolescence or adulthood as small, ‘seed-like’ keratotic papules with peripheral raised rim on the palms and/or soles
  2. clinically may resemble punctate keratoderma, Darier, Cowden, arsenical keratoses
  3. Histologically, cold look like spiny keratoderma and porokeratotic eccrine ostial and dermal duct naevus - but don’t clinically look like each other
42
Q

CDAGS

A

craniosynostosis and clavicular hypoplasia, delayed closure of the fontanelle, anal anomalies, genito-urinary malformations and skin eruption syndrome - get erythematous plaques that histologically look like porokeratosis

43
Q

Porokeratosis histopathology

A
  • Cornoid lamella: thin column of parakeratotic cells
  • underneath, the grnaular layer is often absent
  • Underlying dyskeratosis and pyknotic keratinocytes with peri-nuclear oedema in the spinous layer
  • Dermis may have lymphocytes that may be perivascular, localized beneath the cornoid lamellae or lichenoid
44
Q

Porokeratosis ddx

A
  • All annular
  • AK
  • Linear –> ILVEN, IP stage 2, linear lichen planus
  • Verruca vulgaris has mounds of parakeratosis
45
Q

Porokeratoses treatment

A
  • Surgical:
    • Cryotherapy
    • PDT
    • Shave excision
    • Curettage
  • Topical
    • 5-FU
    • Topical retinoids with 5-FU
    • Imiquimod
    • Tacrolimus
  • Systemic
    • Acitretin
  • Photoprotection!
46
Q

Acrokeratotis Verruciformis of Hopf

A

Clinical

  • Rare, autosomal dominant
  • Multiple skin-coloured, warty papules on the dorsa of the hands
  • Associated with Darier disease (ATP2A2)
  • Can have small, keratin-filled depressions on the palms and soles

Histopathology

  • Hyperkeratosis, papillomatosis and acanthosis
  • Looks similar to seb k

Treatment
- Similar to seb ks and stucco keratoses

47
Q

Cutaneous horn

A
  • White-yellow, hard, keratotic conical lesions
  • Favour sun-exposed sites
  • M>F
  • Lower FP and elderly

Histopathology

  • Hyperkeratosis and parakeratosis with variable acanthosis
  • Atypical keratinocytes of an AK
  • Up to 20% have an SCC or Bowen’s underneath
  • Other lesions that can give rise: verrucae, seb ks, other epithelial neoplasms such as tricholemmomas

Treatment

  • Shave excision
  • Elliptical excision
48
Q

Adnexal neoplasms background

A
  • development of ecrrine apparatus is distinct from folliculosebaceous apocrine unit
  • eccrine glands develop directly from embryonic epidermal anlage during early months of foetal development
  • Follicles arise directly from the epidermis concurrently, but their development differs in that mesenchymal cells descend jointly into the dermis with the developing follicle
  • subsequently, sebaceous and apocrine glands and their ducts elaborate as secondary structures from bulges on the side of the developing follicle
  • Poroma is probably of eccrine lineage
  • Cells with coarsely vacuolated cytoplasm and scalloped nuclei signify sebaceous differentiation
  • Follicular differentiation: presence of bulbar basaloid cells with mesenchymal cells resembling the follicular papilla
  • Apocrine: decapitation configuration at the luminal border
49
Q

Hair follicle naevus

A
  • Small papule with fine hair protrusion
  • typically involve the face and reside near the ear
  • Naevus pilosus: non-vellus hairs
  • Histology: domed surface with an increase in normally formed vellus follicles. Naevus pilosus has closely set terminal follicles
  • Rx: none needed, can excise for cosmesis. Counsel if in child, child will grow and it will be proportionally smaller
50
Q

Trichofolliculoma definition

A
  • these are a group of follicular harmatomas where the fully formed follicular structures emanate from a central dilated infundibular space
  • well differentiated and structured pilar tumour
51
Q

Trichofolliculoma clinical

A
  • papule or nodule involving the face, scalp, upper trunk
  • not clinically distinctive
  • central follicular ostium or punctum may be identifiable, and it may have a small tuft of lightly pigmented hairs
  • Associated with activated beta-catenin mutation - CTNNB1 gene
52
Q

Trichofolliculoma histology

A
  • Central cystic space with infundibular cornification and central orthokeratin
  • Well developed vellus follicles protrude in a radial fashion from the central structure
  • Follicles display a bulb and papilla, and exhibit inner and outer sheath and isthmic differentiation
  • Entire structure enveloped by a vascularized fibrous (angio-fibroma like) stroma
  • If there are sebaceous glands then it is a sebaceous trichofolliculoma
  • Pilar sheath acanthoma:
    • cystically dilated follicular configuration that opens to the surface epithelium
    • lobules of cells that radiate from the cystic dilation recapitulate only the follicular isthmus and outer sheath rather than forming full follicular structures
  • Weedon describes as:
    • Mama hair - central dilated follicle
    • Baby hairs - many smaller baby hairs, often enveloped in vascular fibrotic tumour
    • Looks like ornaments fallen off christmas tree
53
Q

Trichofolliculoma treatment

A

not needed, is benign

54
Q

Fibrofolliculoma, perifollicular fibroma and trichodiscoma clinical and definition

A
  • Adnexal hamartoma that includes both follicular epithelial and mesenchymal elements
    Clinical
  • not clinically distinctive
  • small, skin coloured to hypopigmented papules that involve the head and neck or upper trunk
  • Association: Birt-Hogg-Dube
  • Can also be seen in familial multiple discoid fibromas - no systemic manifestations
55
Q

Fibrofolliculoma, perifollicular fibroma and trichodiscoma histology

A
  • Fibrofolliculoma:
    • mantle, hair follicle with thin cords of epithelium - ‘bat wing like’ and fibrotic stroma
    • slender strands of follicular mantle cells that emanate from folliculosebaceous unit at the level of the isthmus
    • strands are composed of cells with a slightly basaloid appearance
  • Peri-follicular fibroma:
    • almost exclusively stroma, identical to the stromal elements of fibrofolliculoma and angiofibroma
    • spindled and stellate cells arrayed concentrically around follicles and distributed amongst thickened collagen bundles, with proportionate number of intervening small thin-walled vessels
  • Trichodiscoma:
    • more peri-follicular sheath
    • well demarcated
    • Non-encapsulated tumour
56
Q

Fibrofolliculoma, perifollicular fibroma and trichodiscoma treatment

A
  • benign, no surgical
  • cosmesis: superficial electrodesiccation, laser ablation, dermabrasion
  • Topical rapamycin does not work in those of Birt-Hogg-Dube
57
Q

Birt Hogg Dube genetics

A
  • Autosomal dominant

- Gene: FLCN - heterozygous mutation, this encodes folliculin - protein involved in cell-cell adhesion

58
Q

Birt Hogg Dube clinical and investigations

A
  • Clinical:
    • facial or truncal papules that histologically one is fibrofolliculoma, and facial angiofibromas
    • Renal tumours: oncocytomas or renal cell carcinomas
    • Pulmonary: cysts, spontaneous pneumothoraces
    • Colonic polyps
    • Connective tissue naevi
  • Ix:
    • Pulmonary - high resolution CT scan
    • Renal: MRI
59
Q

Birt Hogg Dube Management

A
  • Full body skin examination
  • Pulmonary: smoking cessation, and ++ GA to reduce risk of pneumothorax in surgery
  • Renal: annual renal MRI scan, but if no family history of renal tumours + 2-3 negative scans can do every 2 years
60
Q

Naevus Sebaceous definition and genetics

A
  • Non-neoplastic malformation that includes follicular, sebaceous and apocrine elements + epidermal hyperplasia
    Genetics
  • HRAS 95%, KRAS 5% (also seen in Schimmel-penning - neurocutaneous of one or more sebaceous naevi + neurological involvement)
  • more common mutations lead to activation of MAPK and PI3K-Akt
61
Q

Naevus Sebaceous clinical

A
  • Subtle at birth, slightly raised
  • Face, scalp, neck and rarely the trunk
  • Linear in nature
  • If on scalp - hairless
  • Childhood - thickens and becomes yellow/orange
  • Adolescence: progressive thickening and becomes verrucous
  • If extensive - consider Schimmelpenning syndrome or phakomatosis pigmentokeratotica
  • Development of secondary adnexal neoplasms:
    • trichoblastoma
    • tricholemmoma
    • syringocystadenoma papilliferum
    • apocrine adenoma
    • sebaceous adenoma
    • poroma
    • very rarely: sebaceous carcinoma or apocrine carcinoma
  • If nodule develops –> blue grey nests, if symmetric then trichoblastoma, if asymetric then BCC
62
Q

Naevus sebaceous histology

A
  • principle malformation is the individual folliculosebaceous unit
  • can be microscopically subtle in early stages
  • small apocrine glands
  • epidermal thickening - hyperplasia
  • becomes more papillated, gradually becoming more like an epidermal naevus
  • Late adolescence: acanthosis and fibroplasia of the papillary dermis, enlarged sebaceous glands, underlying follicular units remain smallish
  • can become more verrucous in nature –> believed to be secondary to HPV
  • Secondary neoplasms: trichoblastoma, tricholemmoma, syringocystadenoma
63
Q

Naevus sebaceous treatment

A
  • risk of developing benign growth is relatively high
  • conservative excision in late childhood - narrow excision margins
  • shave or laser don’t work

Derm (57 decks)

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