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Flashcards in Dermatology Deck (134)
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< 1 cm, non-palpable
Ex: petechiae



> 1 cm, non-palpable
Ex: fixed drug eruption,
- annular scaly erythematous patch of tinea,
- subacute lupus
- melanoma



< 1 cm, circumscribed solid/cystic elevation which can be follicular or non-follicular
1. Follicular:
- Equidistant: Fox-Fodyce disease
- Ostia
- Flat-topped papules of lichen
- Verruca vulgaris
- Seborrheic keratosis
- Umbilicated of molluscum contagiosum

2. Pustule: light head on top



> 1 cm
Mesa-like elevation
- Papules may coalesce to form plaque

Ex: psoriasis, eczema



1-2 cm: solid or cystic elevation
- Extensive involvement of the dermis



2+ cm: solid or cystic elevation
- Extensive involvement of the dermis



< 1 cm: usually tense
Ex: herptiform vesicles (Herpes Zoster)



> 1 cm: may be tense or loose collection of fluid
Ex: Bullous pemphigoid
- Bullous Herpes Zoster



Partial loss of epidermis
- Does not bleed
* All blisters, whether vesicles or bullae, eventually form ulcers or erosions

Ex: bullous impetigo (typically staph-mediated exfoliatoxin)
- Pemphigus follaceous



Complete loss of epidermis
- Often bleeds
* All blisters, whether vesicles or bullae, eventually form ulcers or erosions
* Accompanied by fibrin deposition

Ex: shallow ulcerations in Herpes Zoster
- Calciphylaxis (high mortality, seen in dialysis patients)
- Pyoderma gangrenosum (gun-metal gray border)



Formed when there is atrophy of subcutis
Ex: too much cortisone or anabolic steroids injected into skin (often iatrogenic)
- Lupus profundus (panniculitis)- loss of fat under skin)


Color of skin

Red: dilation of vessels modified by density of erythrocytes and inflammatory cells, melanin in epidermis, altered epidermis

Yellow: exogenous pigment, carotene, bile, lipids, solar elastosis, mast cells, altered collagen

Blue: melanin in reticular dermis

Brown/black: hemosiderin, melanin

White: loss of melanin or melanocytes or both



Linear, serpiginous lesions of skin
- Formed when tunnel is formed in epidermis
Ex: scabies



Linear/serpiginous lesion of skin
- Formed when pathologic process involves linear/elongated structure
Ex: thromophlebitis


Risk factors for Melanoma

Familial melanoma: B-K mole syndrome
- Giant congenital nevus > 20 cm
- Bathing trunk nevus

UV radiation: intermittent blistering sunburns early in life
Atypical/dysplastic nevus syndrome patients with multiple clark/dysplastic/atypical nevi


Hereditary Melanoma

VERY rare (< 1% of all melanomas)
Germline mutations
- CDKN2A (p16): cyclin-dependent kinase inhibitor 2A
- High association with pancreatic carcinoma (15% lifetime risk)

* Don't necessarily need to genetically test, most revealed through pedigree


Sporadic melanoma

MUCH more common than hereditary melanoma
Somatic mutations
1. BRAF= serine/threonine kinase mediating pathway of RAS signaling
- Mutation in BRAF--> turns on growth signal
- Seen in 73-82% of melanocytic nevi

2. cKit: associated with acral, mucosal melanomas


Large congenital nevi

"Bathing trunk nevi"
~10% risk of developing melanoma


Skin phototypes

1-6: 1 and 2 most at risk
Type 1: fair skin, hair, freckles


Risk factors for melanoma

UV exposure--> blistering lesions (history of multiple burns in early life)
- One blistering sunburn--> doubles risk
- Intermittent exposure hypothesis (infrequent, heavy sun exposure)

Skin phenotypes:
- light skin
- Blond/red hair
- Blue/green eyes
- Prominent freckling

Clark/dysplastic/atypical melanocytic nevi
- Larger than 5 mm with irregular borders

Family history:
- 10-15% melanoma patients have positive family history
- Younger first-degree relative ex: 40 year old brother (not 85-year old grandmother)


Diagnositc tools for melanoma

Light source, magnification, polarization (dermatoscopy)

Useful adjunct to H&E diagnosis of melanoma
- Poorly differentiated tumors
- Little or no pigment
- Spindle cell tumors
- + pagetoid spread --> not clearly melanoma

MART-1 (Melan-A)
- Most sensitive and specific


Superficial spreading melanoma

Most common subtype:
- Account for 70% of all melanomas
- Diagnosed most often between the ages of 30 and 50 years

Occurs at any site, most frequently:
- Trunk of men
- Legs of women

- Asymptomatic
- Slowly changing from months-years
- Brown to black macule with color variegation and irregular, notched borders
- Best fits the ABCD criteria
- When enters radial growth phase--> papule or nodule
** Can arise de novo or in a pre-existing nevus


Nodular melanoma

Second most common type of cutaneous melanoma:
- Accounts for 15-30% of all melanomas
- Believed to arise as a de novo vertical growth phase tumor without the pre-existing horizontal growth phase

- Mean age of onset is 53 years
- More common in men

- Occurs most frequently on the trunk
- Blue to black, or pink to red-colored, nodule
+/- ulceration

* Tend to be diagnosed at a thicker, more advanced stage with an associated poorer prognosis


Lentigo maligna melanoma

Represents up to 15% of cutaneous melanomas
- Diagnosed most frequently in the 7th-8th decade of life
- Arises in a precursor lesion termed lentigo maligna
- 5% of lentigo malignas progress to invasive melanoma

Pathogenesis: cumulative sun exposure
- Found on chronically sun-damaged skin
- Head and neck
- Preference for the nose and cheek
- Slow growing

Appearance: Ill-defined, asymmetric, brown to black macule with color variegation and an irregular border

* Both LM and LMM more difficult to excise because of ill-defined margins
Least association with nevi


Acral Lentiginous melanoma

5-10% of all melanomas:
- Most common subtype in darker-pigmented individuals
- 60-72% in African Americans
- 29-46% in Asians

Median age of onset being 65 years old
- Most common site is the sole
- Not all palmar or plantar melanomas are ALMs (minority are SSMs or NMs)

- Variegation in color and irregular borders
- May be mistaken for plantar wart or hematoma

More advanced lesion upon diagnosis associated with poorer outcomes
** ALM is not thought to be associated with sun exposure


Subungual melanoma

Variant of ALM:
- Generally arises from the nail matrix
- Most commonly on the great toe or thumb
- A widening, dark, or irregularly pigmented longitudinal nail streak (melanonychia striata)
+/- Nail dystrophy

Hutchinson sign=
- Pigmentation of the proximal nail fold
- Poor prognosis, associated with advanced subungual melanoma


ABCDE of melanoma

A: Asymmetry – one half is not identical to the other half
B: Border – irregular, notched, scalloped, ill-defined
C: Color – Varying shades from one area to the next
D: Diameter – > 6 mm or pencil eraser
E: Evolving

* Other reasons for changes in mole:
- Inflammation
- Folliculitis
- Trauma
- Hormonal influence
- Natural evolution


Histopathology of melanoma

Cytologic atypia:
- Cellular enlargement
- Nuclear enlargement
- Nuclear pleomorphism
- Hyperchromasia of nuclei
- Nucleolar variability
- Mitoses

Architectural disorder:
- Asymmetry
- Poor circumscription
- Variation in size of nests of melanocytes in the lower epidermis and dermis
- Lack of maturation of nests with descent into the dermis
- Pagetoid spread


Desmoplastic melanoma

AKA Neurotropic melanoma

Indurated papule, plaque, nodule
Pigmentation absent in at least 40% of cases (i.e. amelanotic)

Typical locations:
- Head and neck (53.2%)
- Extremities (26.2%)
- Trunk (20.6%)

Mean age 63 years old
Diagnosis is delayed due to non-specific clinical features

Histopathologically, it may simulate fibrosis/scar or a neural neoplasm leading to misdiagnosis and inappropriate treatment


Amelanotic melanoma

Pink/skin colored raised bump- harder to ID as nevi