Dermatology Flashcards
(97 cards)
What is basal cell carcinoma?
Skin neoplasm
AKA rodent ulcer
Summarise the epidemiology of basal cell carcinoma
Commonest form of skin malignancy Common in those with fair skin Common in areas of high sunlight exposure Common in elderly Rare before age of 40 Lifetime risk in Caucasians = 1 in 3
Explain the aetiology of basal cell carcinoma
Prolonged sun exposure/UV radiation
What are the risk factors for basal cell carcinoma?
Prolonged sun exposure/UV radiation Fair skin Gorlin's syndrome - hedgehog IC signalling cascade Arsenic - contaminated well water Xeroderma pigmentosum Transplant patients
What are the presenting symptoms of basal cell carcinoma?
A chronic slowly progressive skin lesion
Usually on face, scalp, ears, trunk
What are the signs O/E of basal cell carcinoma?
Nodulo-ulcerative (most common):
Small gistening translucent skin over coloured papule, visible telangectasia, raised pearly edges
Morphoeic: yellow/white waxy plaque w ill-defined edge, more aggressive
Superficial: multiple pink/brown scaly plaques w fine edge on trunk
Pigmented:
Specks of brown/black pigment may be present in any BCC
How is basal cell carcinoma investigated?
Biopsy rarely necessary
Diagnosis mainly on clinical suspicion
What is erythema multiforme?
An acute hypersensitivity reaction of the skin and mucous membranes
Summarise the epidemiology of erythema multiforme
Any age group
Mainly in children and young adults
Twice as common in males
Explain the aetiology of erythema multiforme
Degeneration of basal epidermal cells
Development of vesicles between cells in basement membrane
Lymphocytic infiltrate around BVs and at dermo-epidermal junction
What are the presenting symptoms of erythema multiforme?
Non-specific prodromal symptoms of URTI
Sudden appearance of itching/burning/painful skin lesions
Skin lesions may fade leaving pigmentation
What are the signs O/E of erythema multiforme?
Classic target (bull’s eye) lesions w rim of erythema surrounding paler area
Vesicles/bullae
Urticarial plaques
Lesions often symmetrical and distributed over arms and legs, including palms, soles, and extensor surfaces
What are the risk factors for erythema multiforme?
Prior occurrence
Herpes simplex virus infection
Mycoplasma pneumonia
How is erythema multiforme investigated?
- Bloods
FBC - abnormal WCC
U+Es - elevated urea, nitrogen/creatinine due to volume depletion - HSV serology
+ve for HSV-1 or 2 IgM if HSV infection - Rapid PCR
+ve for varicella DNA - Cold-haemagglutination serology
+ve if M pneumoniae infection - CXR:
bronchial thickening
interstitial infiltration
Subsegmetnal atelectasis of lower lobe
What is erythema nodosum?
Panniculitis (inflammation of subcutaneous fat tissue) presenting as red or violet subcutaneous nodules
Summarise the epidemiology of erythema nodosum
Usually affects young adults
3x more common in females
Explain the aetiology of erythema nodosum
Delayed hypersensitivity reaction to antigens associated with various infectious agents, drugs and diseases
Commonly SARCOIDOSIS, drugs (sulphonamides, OCP, dapsone, penicillin) + streptococcal infection
How does erythema nodosum present?
Tender red/violet nodules on both shins Sarcoidosis - uveitis, red eyes, retinal nodules, candle-wax drippings Joint pain Fever Signs of underlying cause
How is erythema nodosum investigated?
Determine underlying cause
- FBC - raised WCC
- Anti-streptolysin-O titre - raised in Strep infection
- ESR - raised
- CXR - bilateral hilar adenopathy in sarcoidosis, unilateral in TB, histoplasmosis etc
- PPD skin testing - +ve in TB
What are the risk factors for erythema nodosum?
Streptococcal infection Sarcoidosis Tuberculosis Coccidiodomycosis Histoplasmosis Blastmycosis Behcet's disease OCPs Leprosy
What is a lipoma?
Slow-growing, benign adipose tumours that are most often found in the subcutaneous tissues
Summarise the epidemiology of lipomas?
Seen at any age
More common between 40-60 years
Relatively common
Explain the aetiology of lipomas
Benign tumours of adipocytes
What are the risk factors for lipomas?
Genetic predisposition - familial multiple lipomatosis, Gardner’s syndrome