Pathology of the Skin Flashcards
Macroscopic lesion:
Traumatic lesion breaking the epidermis and causing a raw linear area (i.e.: deep scratch); often self-induced
Excoriation
Macroscopic lesion:
Thickened, rough skin (similar to lichen growth on a rock); usually the result of repetitive rubbing
Lichenification
Macroscopic lesion:
Circumscribed flat lesion usually distinguished from surrounding skin by color, = 5 mm in diameter
Macule
Macroscopic lesion:
Circumscribed flat lesion usually distinguished from surrounding skin by color, > 5 mm in diameter
Patch
Macroscopic lesion:
Separation of nail plate from nail bed
Onycholysis
Macroscopic lesion:
Elevated dome-shaped or flat-topped lesion = 5 mm diameter
Papule
Macroscopic lesion:
Elevated dome-shaped lesion > 5 mm diameter
Nodule
Macroscopic lesion:
Elevated flat-topped lesion > 5 mm diameter; may be formed by coalescence of papules
Plaque
Macroscopic lesion:
Dry, horny, plate-like excrescence; usually the result of imperfect cornification
Scale
Macroscopic lesion:
General term of a fluid-filled raised lesion
Blister
Macroscopic lesion:
Fluid-filled raised lesion = 5 mm diameter
Vesicle
Macroscopic lesion:
Fluid-filled raised lesion > 5 mm diameter
Bulla
Macroscopic lesion:
Itchy, transient, elevated lesion with variable blanching and erythema formed as the result of dermal edema
Wheal
Microscopic lesion:
Diffuse epidermal hyperplasia
Acanthosis
Microscopic lesion:
Loss of intercellular connections between keratinocytes
Acantholysis
Microscopic lesion:
Abnormal, premature keratinization within cells below the stratum granulosum
Dyskeratosis
Microscopic lesion:
Focal discontinuity of the skin showing incomplete loss of the epidermis
Erosion
Microscopic lesion:
Infiltration of the epidermis by inflammatory cells
Exocytosis
Microscopic lesion:
Intracellular edema of kertinocytes, often seen in viral infections
Hydropic swelling/ballooning
Microscopic lesion:
Hyperplasia of the stratum granulosum, often due to intense rubbing
Hypergranulosis
Microscopic lesion:
Hyperplasia of the stratum corneum, often associated with a qualitative abnormality of keratin
Hyperkeratosis
Microscopic lesion:
A linear pattern of melanocyte proliferation within the basal cell layer
Lentiginous
Microscopic lesion:
Surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae
Papillomatosis
Microscopic lesion:
Keratinization with retained nuclei in the stratum corneum (normal in mucous membranes)
Parakeratosis
Microscopic lesion:
Focal discontinuity of the skin showing complete loss of the epidermis, revealing dermis or subcutis
Ulceration
Microscopic lesion:
Intercellular edema of the epidermis
Spongiosis
Microscopic lesion:
Formation of vacuoles within or adjacent to cells; often refers to basal cell-basement membrane zone area
Vacuolization
Common nevus with the following description:
- < 6 mm in diameter
- uniformly pigmented
- regular, well-defined
- mostly in sun-exposed areas
- no atypia, absent mitosis
- no dermal reactions
- RAS mutations (pro-growth signalling but intact tumor suppressant p16 prevents progression)
- follows a maturation sequence
Melanocytic nevus
Common nevus with the following description:
- > 5 mm in diameter
- variegated pigments with pebbly surface
- irregular borders, can be target-like with darker raised center and irregular flat periphery
- found in both sun-exposed and non-sun-exposed areas
- with lentiginous hyperplasia as nevus cells replace the normal basal cell layer along the dermo-epidermal junction
- with atypia and mitosis
- lymphocytic infiltration, linear fibrosis, and melanin incontinence
- CDKN2A mutation (impaired tumor suppression activity), TERT (telomerase activation, prolonging cell life), RAS mutation (pro-growth signalling)
- marker for melanoma risk
- follows a turmor progression sequence
Dysplastic nevus
Syndrome of multiple (hundreds) of dysplastic nevi that is also a risk factor for melanoma
Dysplastic nevus syndrome
1st stage of melanocytic nevus MATURATION SEQUENCE:
- nevus cells at the dermo-epidermal junction
- growth pattern: nests
- cells round, uniform, with inconspicuous nucleoli and no mitosis
- tyrosinase-positive
- cholinesterase-negative
Junctional nevus
2nd stage of melanocytic nevus MATURATION SEQUENCE:
- nevus cells at the dermo-epidermal junction AND dermis
- growth pattern: nests
- cells round, uniform, with inconspicuous nucleoli and no mitosis
- tyrosinase-positive
- cholinesterase-negative
Compound nevus
3rd stage of melanocytic nevus MATURATION SEQUENCE:
- nevus cells at the dermis
- growth pattern: nests
- cells round, uniform, with inconspicuous nucleoli and no mitosis
- tyrosinase-positive
- cholinesterase-negative
Intradermal nevus
4th stage of melanocytic nevus MATURATION SEQUENCE:
- nevus cells at the dermis
- growth pattern: fascicles
- fusiform cells, spindle-shaped but non-dysplastic
- tyrosinase-negative
- cholinesterase-positive
Intradermal nevus with neurotization
Rate-limiting enzyme responsible for melanin regulation
Tyrosinase
Tyrosinase from melanocytes cleaves tyrosine, precursor to melanin and other pigments
1st stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE:
- involves the basal layer of the epidermis (dermo-epidermal junction)
- no atypia and mitosis
Lentiginous junctional nevus
2nd stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE:
- involves the dermis and epidermis (with atypical cells in epidermis)
- with atypia and mitosis
Lentiginous compound nevus
3rd stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE:
- involves the epidermis and superficial dermis
- with atypia and mitosis
- radial growth only
Early melanoma