225 - Malignant Melanoma Flashcards
what is an unraised localise area of skin colour/texture change called?
macule
what is an elevation of skin
papule
what is an elevation of skin >5mm dia called?
nodule
what is a small blister
vesicle
what is a large blister >5mm of clear fluid called?
bulla
what is a blister with visible collection of free pus called?
pustule
what is a nodule consisting of an epithelial lined cavity filled with fluid or semi solid material called?
cyst
what is a transitory compressible papule or plaque of dermal oedema called?
wheal
what is a palpable plateau like elevation of skin called?
plaque
what is a accumulation of thickened horn layer keratin called?
scale
what is an area of skin loss extending into the dermis called?
ulcer
define eczema and how it presents?
skin barrier dysfunction of genetic susceptibility due to an abnormal immune response (IgE raised in 80% of atopics)
Itcy, red, weepy in acute, dry scaly and lichenified in chronic
what therapy is available for eczema?
irritant avoidance, emollient, soap substitute, topical steroid, topical calcineurininhibitors, bandages.
In more serious oral ABX/steroids, phototherapy, systemic therapies
what is the difference between irritant contact dermatitis and allergic contact dermatitis?
irritant - disruption of skin barrier, irritants damage keratinocytes + inflammatory mediators released
allergic - allergen picked up by APCs and causers immunological memory
what allergy tests exist?
- IGE RAST for tyI (intermediate) hypersensitivity
* Patch testing for TyIV (delayed) hypersensitivity
name topical steroids from weak to very potent
- H - weak - hydrocortisone
- E - mod potent - Eumovate (clobetasol butyrate)
- B - potent - Betnovate (betamethasone valerate)
- D - very potent - Dermovate (clobetasone proprionate)
how can sun exposure cause skin cancers?
*IV damages cellular DNA
*Tumour suppressor genes often disabled by UV - TP53 mutation (90% of SCCs), TP16 mutation
can be dysfunctional due to dentics +exoderma pigmentosum and basal cell naevus syndrome
who is at risk from malignant melanoma skin cancer?
- neoplasm of melanocytes or daughter cells
- middle aged females with white tyI skin
- sunburn, p16 tumour surpressor protein defects, congenital naevi or high numbers of atypical (irregular colour/shape) naevi
how does malignant melanoma develop?
- radial growth phase - outwards
* vertical growth phase - invade dermis and can metastasise
what are the signs of malignant melanoma and investigations?
- asymmetry
- irregular border
- irregular colour - black or blue
- diameter >6mm
- evolving
- nodular most dangerous - elevated, firm, growing
- excisional biobsy (Breslow thickness)
- imaging for mets
treatment for malignant melanoma?
surgical - increase margins (2-3 cm), sentinel node biopsy, adjuvant IFN-alpha
what is small cell carcinoma skin cancer and what causes it?
- invasive neoplasm of keratinocytes - Bowen’s disease (in-situ (not invaded through basal lamina). Affects elderly men with ty1 skin (70y/o)
- mostly due to sun damage afecting TP53 gene, viruses, heavy metals or immunosupression
- may develop from existing actinic keratoses
how does small cell carcinoma skin cancer present?
- red scaly lesions with endurated base on sun exposed areas. May ulcerate later
- investigations - biopsy, imaging for mets
treatments for small cell carcinoma skin cancer?
- exicisional biopsy with margins
- radiotherapy
- cryotherapy
- chemotherapy 5-fluorouracil cream
- photodynamic therapy
- immunotherapy - imiquimod cream
describe basal cell carcinoma skin cancer?
- most common tumour in white people
- locally invasive rarely mets
- risks - sun exposure, fair skin, age, previous radio, tars and arsenic
- nodular - cystic lesion or pigmented
- treatment - excision, radio, cryotherapy if superficial
describe squamous carcinoma skin cancer?
- less common than BCC - may arise from AK or bowens
- lips, mouth, ears, scalp. risks smoking or chew tobacco, sun, alcohol
- ulcerating lesions or scaly enlarging nodules
- treatment - surgical or radio if frail
name some common skin commensals
staph epidermidis
diptheroids (corynebacterias)
micrococci
more dangerous staphylococcus aureas (carried by 20%), streptococcus pyrogenes (carried in 10% in throat)
what problems can staphylococcus aureus skin infections cause?
- majority produce B-lactamase and th. resistant to penicillins (eg MRSA). Use Flucloxacillin, Methicillin, Co-Amoxiclav
- They produce exotoxins - proteases that breakdown dermosomes and superantigens like TSST-1 bind irreversibly to Tcells (massive immune response)
- produce superficial localised infections with no systemic symptoms - Imetigo and ecthyma, folliculitis/furuncles, abcesses, carbuncles
- use flucoloxacillin or erythromicin
what problems can streptococcus pyrogenes skin infections cause?
Deeper, spreading infections with systemic symptoms - Erysipelas, cellulitis, abcesses, necrotising fasciitis
*Use amoxycillin or erythromicin
what infections do corynebacterium cause?
- Erythrasma - hyperpigmented macular patches
* pitted keratolysis - pits in superficial skin (on soles of feet) - treat with topical ABX +/- antifungals
describe syphilis
- treponema pallidum spirochaete (gram -ve bacteria)
- solitary red papule at site of infection leading to painless non bleeding ulcer then secondary symmeteric pink/brown macular rash 3-4 months after then necrotic papules (patchy alopecia)
- treat with penicillin
describe lyme disease
- borrelia Burgdoferi spirochaete (gram -ve bacteria) trasmitted by tick bite
- erythema migrans - growing bulls eye rash around bite then systemic symptoms, facial palsy, arthritis
- treat with penicillin
what skin infections can mycobacteria cause?
- lupus vulgaris - by M.tuberculosis - tuberculous lesions around face
- fish tank granuloma - by M.Marinum - red scaly plaque on arm
what causes thrush (candidaiasis) how how should it be treated?
*yeast (unicellular fungi) mainly candida albicans
*risks - moist skin folds, obesity/DM, imunnosupression, poor hygiene
*causes itchiness/soreness, continuous red vesiculopustular rash, maceration and fisuring of skin, white plaques, white discharge from genitals
*treat - oral - amphotericin, nystatin or micronazole
skin - topical imidazoles
what skin problems do dermatophytes cause?
- multicellular fungi (3types trichopyton, epidermophyton, microsporum)
- types tinea - coporis (body), pedis (foot), unguium (nail), cruris (groin), manuum (hand), capotis/kerion (head)
- treat - topical imidalzoles. systemic Itraconazole, terbinafine, greiseofulvin
What is the difference in rashes between DNA and RNA viruses?
- RNA - morbilliform rash like measles eg paramyxoviridae
* DNA - vesicular rash like pox eg herpes viruses, varicella zoster
how does measles (rubeola) present?
- transmission via respiratory droplets, URT infection, spreads to lymphatics then organs and skin
- prodromal phase (fever, malaise,anorexia, cough, conjunctivitis and coryza), koplik’s spots (blue grey) on buccal mucosa, rash 4 days after starts on face the spreads (red macular lesion) and lymphadenopathy
- treat with abx if 2ry bac. infection
how does herpes simplex virus 1 and 2 present?
- passed by direct contact or fluid exchange
- penetrates skin or mucous membrane then destroys epidermal cells then latent in dorsal root ganglia
- HSV1 acute herpetic gingivostomatitis or acute herpetic pharyngotonsillitis both with fever and malaise & vesicular lesions. Then recurrent with herpes labialis - prodrome of pain, tingling and burning then paulse>vesicles>pustules/ulcers
- HSV2 prodrome of pain and burning then eruption of vesicles>ulcers
- investigations tzanck smear, viral tissue culture, PCR
- treat - antivirals Penciclovir, aciclovir
how does varicella zoster virus present?
- URT infection, then to lymph nodes then whole body via immune cells. stays dormant in one or more dorsal spinal/cranial ganglia
- varicella (chicken pox) - prodromal phase then rash 3-6 days after staring on trunk/face the spreading. paular>vesicula>pustular>crusted
- zoster (shingles ) - prodromal phase, pain & paraesthesia, depression, flu. vesicular rash in unilateral dermatomal distribution papules>vesicles>crust
- investigations tzanck smear, tissue culture, PCR
- treat - aciclovir
what cells are in the epidermis?
keratinocytes melanocytes and langerhans cells (dendritic)
what are the 5 strata of the epidermis (no blood supply)?
- stratum corneum - dead flattened keratinocytes fused into sheets
- stratum lucidum - dead keratinocytes undergoing keratinisation
- stratum Granulosum - keratinocytes undergoing cell death, flattening and keratinisation
- stratum spinosum - keratinocytes starting keratinisation * langerhan cells
- statum basale (germinativum) - keratinocyte stem cells and melancytes
what makes up the dermis?
- papillary layer - thin layer of colalgen, rich capilary (and shunt vessel) network supplying O2 and nutrients to lower strata of epidermis. Responisble for temp regulation
- reticular layer - thick later of dense collagen and elastic tissue providing strength and supporting structures (follicles, glands).
- nerve endings - meissner’s (light touch) and pacinian’s (pain and pressure) corpuscules
what does the hypodermis do?
fat storage
