Pathology of Skin Lesions Flashcards
(41 cards)
Define…
- hyperkeratosis
- parakeratosis
- acanthosis
Hyperkeratosis = increased thickness of the keratin layer
Parakeratosis = persistence of nuclei in the keratin layer
Acanthosis = increased thickness of the epithelium
What does parakeratosis signify?
That the epidermis is turning over too quickly
This is because the nuclei are usually lost before they reach the keratin layer
Define…
- papillomatosis
- spongiosis
Papillomatosis = irregular epithelial thickening
Spongiosis = areas of oedema between the squamous cells of the epidermis
Which disease is spongiosis characteristic of?
Eczema
What are the 4 main classifications of inflammatory skin disease?
- Spongiotic
- Psoriasiform
- Lichenoid
- vesiculobullous
Describe the following inflammation patterns:
- Spongiotic
- Psoriasiform
- Lichenoid
- vesiculobullous
- Spongiotic = oedema in the epidermis e.g., eczema
- Psoriasiform = elongation and clubbing of the epidermal ridges e.g., psoriasis
- Lichenoid = basal layer damage e.g., lichen planus
- Vesiculobullous = blistering conditions e.g., pemphigoid
What are cytoid bodies?
Dead keratinocytes
How would you describe the histology of lichenoid inflammation?
- Sawtoothed dermo-epidermal junction
- Cytoid bodies in the basal layer
- Hyperkeratosis
- Hypergranulosis
- Inflammatory infiltrates in the upper dermis
What are immunobullous diseases? Give 3 examples
Diseases that have blisters as their primary feature
Pemphigus, bullous pemphigoid, dermatitis herpetiformis
Which pathological process is found in all variants of pemphigus?
Acantholysis
What is acantholysis?
Loss of communication between epidermal cells
What is the difference between the location of the blisters seen in pemphigus vulgaris and bullous pemphigoid?
Pemphigus vulgaris = in the upper layers of the epidermis
Bullous pemphigoid = subepidermal blister (under the dermis)
Early in embryogenesis, melanoblasts migrate from the neural crest to the… (3)
- Skin
- Uveal tract (middle layer of eye)
- Leptomeninges (2 innermost membranes surrounding the brain and spinal cord)
In the basal layer, what is the ratio of melanocytes to keratinocytes? (roughly)
1:5 to 1:10
Individuals with darker skin have more melanocytes. T/F
False
Melanocyte ratio is constant irrespective of race - it is the melanin content within them that differs
Which gene determines the balance of pigment in the skin and hair?
MC1R gene
What does 1 faulty copy of MC1R cause?
What does 2 copies cause?
1 copy: freckling
2 copies: red hair and freckles
What are ephilides?
Freckles
Why do freckles occur?
After sun exposure due to the clumpy distribution of melanocytes
What are actinic lentigines and what are they caused by?
‘Age’ or ‘liver’ spots most commonly found on the face and dorsal hands
They are related to UV exposure
What are the 4 main types of malignant melanoma?
- Superficial spreading (most common, affecting trunk and limbs)
- Acral/mucosal lentiginous (affecting mucosal and peripheral parts)
- Lentigo maligna (affecting sun-damaged areas)
- Nodular (varied sites but often trunk)
Describe the 2 growth phases of a non-nodular melanoma
Radial growth phase (RGP) - grows horizontally either entirely in-situ or with dermal microinvasion
Vertical growth phase (VGP) - melanoma cells invade the dermis, forming an expansile mass with mitoses
Melanomas can metastases in radial and vertical growth phase. T/F?
False
They can only metastases in VGP
Why can melanomas only metastases in VGP?
They have access to lymphatics and blood vessels in the dermis
