Dermatology Flashcards
What is the proper name for a strawberry birthmark? Describe its features.
Cavernous/infantile haemangioma or strawberry naevus
- raised or flat
- usually involutes (decreases in size normally)
- intervention req. if lesion involves the eyes (causes ambylopia - use propanolol), if it ulcerates/bleeds frequently (shunts large volumes of blood, can cause cardiac failure or consume clotting factors - Kasabach-Merritt syndrome)
What is the proper name for a port wine stain? Describe its features.
Capillary haemangioma
- laser treatment req. to remove
- 2% have Sturg-Weber syndrome: calcified meningeal capillaries on ipsilateral side which causes epilepsy, hemiplegia, and bupthalmos (eyeball enlargement) (esp. if lesion is in distribution of CNV1)
- if near or one the eye there is a risk of glaucoma (ophthalmic assessment req.)
What are Campbell de Morgan spots?
Cherry angioma
Common, benign angiokeratomas which appear as pinpoint red papules
- esp. on trunk
- increased no. & freq. with age
- no treatment req.
What are spider naevi? Describe its features.
Swollen, dilated central arteriole with red “spider legs” (veins) which can be occluded with pressure (veins refill from centre).
Located in distribution of the SVC (face, neck, upper trunk & arms).
Caused by increased oestrogen
- pregnancy
- liver disease: reduced oestrogen metabolism causing gynaecomastia, testicular atrophy, etc.
- HRT
What are the features of a papilloma?
Benign tumour derived from epithelium
Can be smooth and pedunculated (e.g. skin tag), sessile (e.g. HPV wart) or pigmented (e.g. melanoma)
What are the key features which help diagnose a skin lump?
Is the lump IN the skin (moves with the skin)?
Is the lump BENEATH the skin (skin moves over it)?
Is the lump FLUCTUANT (i.e. fluid-filled)?
- put fingers either side and use other finger to push down on lump
What is a neurofibroma?
Benign nerve sheath tumour in PNS.
Can occur on their own or as part of neurofibromatosis
- acoustic neuromas (CNVIII)
- café au lait patches
Can be dermal (originate in the nerves of the skin) or plexiform (originate in the nerves of the skin or from internal nerve bundles).
What is a café au lait patch?
Permanent light brown flat macule caused by a collection of melanocytes in the epidermis which may be associated with neurofibromatosis (5
What is a dermatofibroma/histiocytoma?
Firm elevated pigmented nodule in skin containing histiocytes (histamine, therefore very itchy).
Often caused by insect bites.
Excise to release.
Describe the features of a lipoma.
Most common type of benign soft tissue tumour, composed of adipose tissue (therefore non-fluctuant).
Describe the features of a ganglion cyst.
Benign lump beneath skin caused by leakage of synovial fluid from a joint into a cavity (most common in the hands and feet).
- myxoedamatous (“jelly-like”) degeneration of joint sheath
- can burst by hitting with a book/pushing down with fingers
- can use wide bore needle to suck out fluid
Describe the features of an epidermal (sebaceous) cyst.
Cystic swelling of skin with central punctum containing keratin (therefore found everywhere apart from palms and soles)
Frequently infected by Staph. aureus
Known as pilar cysts when on scalp within hair
Describe the features of a dermoid cyst.
Arise from cystic changes in epithelial remnants sequestered beneath the skin at lines of embryological fusion (midline).
Contains keratin, hair, sebaceous glands.
Commonly found in the midline, retroauricular, and on lateral canthus.
Contrast ovarian dermoid cysts with testicular teratomas.
Ovarian dermoid cyst = mature cystic ovarian teratoma
Testicular teratomas (seminomas) are more malignant (increased rate of cell turnover compared to ovaries).
Describe the features of an implantation dermoid cyst.
Penetrating injury (e.g. rose thorn) causes implantation of epidermal fragments into the dermis —> epidermis continues to grow and forms a cyst lined with stratified squamous epithelium and filled with keratin.
Describe the features of a pilonidal sinus.
Cyst/abscess (Staph. aureus) near or on the natal cleft (intergluteal cleft) which contains hair and skin debris.
Hairs pushed beneath skin causes foreign body reaction.
Excise down to the sacrum and heal by secondary intention.
Describe the features of seborrhoeic keratosis.
Benign tumour of keratinocytes which increase in frequency with age.
Mostly found on back.
Describe the features of a pyogenic granuloma.
Benign tumour of blood vessels following trauma e.g. rose thorn.
- friable
- often found on fingers/lips
- excise to prevent transformation into melanoma
What is a keratocanthoma?
Keratin horn
What is a hypertrophic scar? Contrast to a keloid scar.
Hypertrophic scar = raised scar caused by excessive collagen deposition
Keloid scar = excessive collagen production occurring following injury
- common in West Africans/Carribbeans
- common on the sternum
- pointless to excise
What is erythema ab igne?
Skin condition caused by longterm exposure to heat.
Causes:
- laptops
- hot water bottles (esp. for chronic pain e.g. pancreatitis)
Pain worse at night due to reduced sensory input
What are the different types of skin lesion shapes? Give examples of each.
Sloping e.g. healing venous ulcer
Punched-out e.g. diabetic ulcer (trophic, arterial, or neuropathic)
Undermined e.g. pressure sore on buttock (can fit hand under surrounding skin)
Rolled e.g. basal cell carcinoma
Everted e.g. squamous cell carcinoma (sun exposure, immunosuppression, coal - chimney sweep and scrotal SCCs)
What is hidradenitis suppurativa?
Cluster of abscesses in areas containing many apocrine sweat glands (e.g. armpits, under breasts, inner thighs, groin, buttocks) caused by repeated infection of hair follicles.
Excision required.
What is a carbuncle?
Combination of furuncles (boils) formed by Staph. aureus infection.
Classically on the face.
Excise and let heal by secondary intention.
