Robbins Flashcards
most common pigmented lesions of childhood in lightly pigmented individuals
Freckle (Ephelis)
essential histologic feature is linear (nonnested) melanocytic hyperplasia
lentigo
Melanocytic nevi (known colloquially as moles) are common benign neoplasms caused in most cases by acquired activating mutations in ____ and ____
NRAS and BRAF
melanocytic nevi which consist of aggregates or nests of round cells that grow along the dermoepidermal junction
junctional nevi
event where nevi acquire fusiform contours and grow in fascicles resembling neural tissue
neurotization
conventional nevi, frequently have acquired activating mutations in the NRAS and BRAF genes, what are the additional mutations in dysplastic nevi? (2)
CDKN2A and CDK4
T/F dysplastic nevi occur only on sun-exposed body surfaces.
False
they occur on both sun-exposed and protected body surfaces
most deadly of all skin cancers and is strongly linked to acquired mutations caused by exposure to UV radiation in sunlight
melanoma
frequent “driver” mutations in melanoma (3)
Mutations that disrupt cell cycle control genes - CDKN2A
Mutations that activate pro-growth signaling pathways - RAS and PI3K/AKT pathway
Mutations that activate telomerase - TERT
most commonly mutated gene identified in melanoma
TERT
phase in melanoma growth wherein it still lacks the capability to metastasize
radial growth phase
melanoma growth phase during which the tumor cells invade downward into the deep dermis as an expansile mass and is heraleded by the appearance of a nodule
vertical growth phase
mutation found in many sporadic seborrheic keratoses and are thought to drive the growth of the tumor
FGFR3
Seborrheic keratoses may suddenly appear in large numbers as part of this paraneoplastic syndrome
Leser-Trélat sign
marked by thickened, hyperpigmented skin with a velvet-like texture that sometimes appears as a paraneoplatic syndrome usually gi adenocarcinoma
Acanthosis nigricans
the familial form of Acanthosis nigricans is associated with germline activating mutations in
FGFR3
multiple trichilemmomas are associated with what syndrome?
Cowden syndrome
composed of islands of cells resembling the normal epidermal or adnexal basal cell layer (basaloid cells).These islands fit together like pieces of a jigsaw puzzle within a fibrous dermal matrix
cylindroma
proliferation of basaloid cells that forms primitive structures resembling hair follicles
trichoepithelioma
shows a lobular proliferation of sebocytes with increased peripheral basaloid cells and more mature sebocytes in the central portion that have frothy or bubbly cytoplasm due to the presence of lipid vesicles
sebaceous adenoma
composed of basaloid cells that show trichilemmal or hair-like differentiation similar to that seen in the germinal portion of the normal hair bulb in the anagen growth phase
pilomatrixoma
shows infiltrative cells with ductal differentiation with prominent decapitation secretion similar to that seen in the normal apocrine gland
apocrine carcinoma
most important cause of cutaneous squamous cell carcinoma is
DNA damage induced by exposure to UV light
premalignant lesion that occurs in sun damaged skin
actinic keratosis
Basal cell carcinoma is a distinctive locally aggressive cutaneous tumor that is associated with mutations that activate the ____ pathway
Hedgehog signaling pathway
most common invasive cancer in humans
basal cell carcinoma
gene associated with nevoid basal cell carcinoma syndrome (NBCCS) (also known as basal cell nevus or Gorlin syndrome)
PTCH (patched)
invasive cords and islands of variably basophilic cells with hyperchromatic nuclei, embedded in a mucinous matrix and often surrounded by many fibroblasts and lymphocytes. The cells at the periphery of the tumor cell islands tend to be arranged radially with their long axes in parallel alignment
basal cell carcinoma, nodular type
These tumors consist of benign, spindle-shaped cells that are usually arranged in a well-defined, nonencapsulated mass within the mid-dermis
dermatofibroma
best regarded as a well-differentiated, primary fibrosarcoma of the skin. It is composed of closely packed fibroblasts arranged radially, a pattern referred to as storiform. Mitoses are rare. The overlying epidermis is generally thinned. Deep extension from the dermis into subcutaneous fat, producing a characteristic “honeycomb” pattern, is frequently seen
Dermatofibrosarcoma protuberans
The molecular hallmark of dermatofibrosarcoma protuberans is a translocation involving the genes __ and ___ and leads to overexpression and increased secretion of ____
COL1A1 and PDGFB, PDGFB
Histologic landmark of cutaneous T-cell lymphoma (CTCL) is the presence of atypical cells that characteristically form band-like aggregates within the superficial dermis and invade the epidermis as single cells and small clusters called
Pautrier microabscesses
encompasses a spectrum of rare disorders characterized by increased numbers of mast cells in the skin and, in some instances, in other organs as well
mastocytosis
Many cases of mastocytosis have acquired activating point mutations in
KIT
mass forming increase in mast cells around superficial dermal blood vessels to large numbers of tightly packed mast cells in the upper to mid-dermis
mastocytoma
Granules in mast cells may be visualized with
toluidine blue or giemsa
X-linked ichthyosis is caused by a deficiency of
steroid sulfatase
exhibit a buildup of compacted stratum corneum that is associated with loss of the normal basket-weave pattern and there is generally little or no inflammation
ichthyosis
Eczematous dermatitis typically results from this type of hypersensitivity
T cell– mediated inflammatory reactions (type IV hypersensitivity)
a lymphoma of skin-homing CD4+ T-helper cells that presents in the skin
mycosis fungoides
characterized by keratinocyte injury mediated by skin-homing CD8+ cytotoxic T lymphocytes
Erythema multiforme
typical lesion is a well-demarcated, pink to salmon-colored plaque covered by loosely adherent silver-white scale. There is increased epidermal cell proliferation results in marked epidermal thickening (acanthosis), with regular downward elongation of the rete ridges sometimes described as appearing like test tubes in a rack
psoriasis
skin layer that is thinned or absent in psoriasis
stratum granulosum
In psoriasis the abnormal proximity of vessels within the dermal papillae to the overlying parakeratotic scale accounts for the characteristic clinical phenomenon of multiple, minute, bleeding points when the scale is lifted from the plaque and this is called
Auspitz sign
Characteristic of psoriasis is the finding of neutrophils forming small aggregates within the superficial epidermis called _____ and the parakeratotic stratum corneum called _____
spongiform pustules, munro microabscesses
a chronic inflammatory dermatosis classically involves regions with a high density of sebaceous glands
seborrheic dermatitis
lesions can be induced in susceptible individuals by local trauma, a process known as
Koebner phenomenon
Koebner phenomenon can be observed in __ and ____
psoriasis and lichen planus
papules of lichen planus are often highlighted by white dots or lines called
Wickham striae
Lichen planus is characterized histologically by a dense, continuous infiltrate of lymphocytes along the dermoepidermal junction called
interface dermatitis
a blistering disorder caused by autoantibodies that result in the dissolution of intercellular attachments within the epidermis and mucosal epithelium
Pemphigus
are functionally interchangeable components of desmosomes but have different distributions within the epidermis (2)
Desmoglein 1 and 3 (Dsg1 and Dsg3)
T/F Dsg3 is most abundant in the superficial skin
False, more abundant in the basal layer
T/F Dsg1 is most abundant in the superficial skin
True
pemphigus type where in autoantibodies against Dsg1 and Dsg3 cause blisters in the deep suprabasal epidermis
pemphygus vulgaris
pemphigus type where in autoantibodies target Dsg1 only
pemphigus foliaceus
lesions where in autoantibodies bind BPAG2, a component of the hemidesmosomes, leading to blister formation at the level of the lamina lucida of the basement membrane
bullous pemphigoid
lesion where in IgA autoantibodies attach to the fibrils that anchor hemidesmosomes to the dermis
dematitis herpetiformis
pemphigus associated with various malignancies, most commonly non-Hodgkin lymphoma.
Paraneoplastic pemphigus
T/F All forms of pemphigus are autoimmune diseases caused by IgG autoantibodies against desmogleins that disrupt intercellular adhesions and result in the formation of blisters.
True
common histologic feature in all forms of pemphigus is
acantholysis
identification of subepidermal, nonacantholytic blisters points to
bullous pemphigoid
protein target of antibodies in bullous pemphogoid
BPAG2
Lesion where in fibrin and neutrophils accumulate selectively at the tips of dermal papillae, forming small microabscesses. The basal cells overlying these microabscesses show vacuolization and focal dermoepidermal separation that ultimately coalesce to form a true subepidermal blister. By direct immunofluorescence, it shows discontinuous, granular deposits of IgA that selectively localize in the tips of dermal papillae
dermatitis herpetiformis
blanket term for a group of disorders caused by inherited defects in structural proteins that lend mechanical stability to the skin. The common feature is a proclivity to form blisters at sites of pressure, rubbing, or trauma, at or soon after birth.
epidermolysis bullosa
Cutaneous manifestations consist of urticaria and vesicles associated with scarring that are exacerbated by exposure to sunlight. The vesicles are subepidermal in location, and the adjacent dermis contains vessels with walls that are thickened by glassy deposits of serum proteins, including immunoglobulins
porphyria
acne type composed of open and closed comedones
non-inflammatory acne
stage of rosacea where there is permanent thickening of the nasal skin by confluent erythematous papules and prominent follicles
rhinophyma
individuals with rosacea have high cutaneous levels of the antimicrobial peptide ____
cathelicidin
inflammatory reaction in the subcutaneous adipose tissue that may preferentially affect the lobules of fat or the connective tissue that separates fat into lobules
Panniculitis
is a form of secondary panniculitis caused by self-inflicted trauma or injection of foreign or toxic substances
Factitial panniculitis
squamoproliferative lesions caused by human papillomaviruses (HPVs)
Verrucae
lesions show cup-like verrucous epidermal hyperplasia.The diagnostically specific structure is a large (up to 35 μm), ellipsoid, homogeneous, cytoplasmic inclusion that is found in the cells of the stratum granulosum and the stratum corneum
molluscum contagiosum
The pathogenesis of blister formation in impetigo is related to bacterial production of a toxin that specifically cleaves ____
Dmg1
