wound healing Flashcards
what is a wound
loss of integrity of skin tissue
what causes chronic wounds (2)
- disruption in normal healing process;
- slowed/incomplete healing
3 phases of wound healing (post fibrin plug formation)
- inflammatory phase (0-48hrs);
- proliferative phase;
- maturation and remodelling phase (3+ weeks)
all over lapping, not clearly separated from each other
clinical signs of the inflammatory phase (4)
rubor, tumor, dolour, calor
3 main steps in the inflammatory phase
- wound cleaning (phagocytosis - monocytes, macrophages, lymphocytes);
- chemo-attraction (growth factors, cytokines, fibroblasts/immune cells);
- structural framework development (temporary matrix)
3 main stages of the proliferative phase
- net collagen synthesis (GFs, ECM molecules etc.);
- increased wound tensile strength (epidermal cells proliferate and move to wound edge/granulation tissue, mylofibroblasts generate force to contract and close wound);
- scar formation (apop of immune cells, fibroblasts etc.; remaining fibroblasts lay down collagen)
what happens in the maturation/remodelling phase
reorganisation of collagen - Type 1 and 3
2 types of wound healing
primary intention; secondary intention
6 things that can affect wound healing
- size of wound;
- blood supply to area;
- presence of foreign bodies or microorganisms;
- age/health of a pt;
- nurtitional status;
- drugs (e.g. steroids)
primary intention vs secondary intention
primary - e.g. surgical incision; immediate closure of wound edges when no loss of tissue has occured -> rapid epithelial coverm faster healing, better cosmetic result;
secondary - e.g. trauma; spontaneous healing of wound without direct closure -> granulation, slow epithelial cover, wound contraction, compromised cosmetic result
2 types of wound healing
primary intention; secondary intention
primary intention healing pathway (4)`
- wound edges joined by fibrin plug;
- regrowth of basal layer of epidermis;
- lysis of fibrin and re-epithelialisation;
- restoration to intact skin
secondary intention healing pathway (4)
- large defect filled by fibrin clot;
- new blood vessels and fibroblasts (granulation tissue) grow from the dermis into fibrin;
- collagen laid down by granulation tissue fibroblasts to restore integrity;
- maturation of collagen achieves structural integrity and allows regrowth of epidermis
what is tertiary intention healing
healing after traumatic injury, dirty surgery, delayed primary intention etc. -> initially left open after removal of all non-viable tissue, wound edges brought together after a few days when it appears clean and well vascularised
examples of treatments for skin lesions (8)
- cryotherapy;
- creams/ointments;
- photodynamic treatment;
- curretage
- shave excision
- excision
- RT
- chemo
how does cryotherapy cauuse cell death (4)
- ice crystal formation;
- osmotic differences -> cell disruption;
- ishaemic damage
- immunological stimulation
what is usually used for cryotherapy
liquid nitrogen
4 contraindications for cryotherapy
- pigmented lesions;
- malignant lesions (needs histology);
- cold urticaria;
- lesion of uncertain diagnosis
what is 5-flurouracil cream and when is it used
an anti-metabolite that inhibits pyrimidine metabolism and DNA synthesis; used for multiple AKs (too many for cryo), BCCs, Bowen’s disease
what condition is cryotherapy most commonly used for
actinic keratosis
what is aldara (imiquimod 5%) and when is it used
an iminazoquinolone that acts as an immune response modulator -> stimulates release of cytokines;
used for genital warts, superficial basal cell carcinoma, and actinic keratosis
what is photodynamic therapy
the activation of topical porphyrin cream (psorelin) to destroy cancer/pre-cancer -> scale removed, cream applied and then light shone onto sensitised area
3 contraindications for photodynamic therapy
- pigmented lesions;
- non-histologically sampled malignant lesions;
- patients unable to tolerate pain
what is curretage/cautery and when is it used
lesion is scraped off and heat is applied to skin surface;
used for pyogenic granuloma, cutaneous horn (AK), seborrhoeic wart, small nodular BCCs
5 contraindications of cutterage/cautery
- pigmented lesions;
- BCCs (morphoeic, infiltrating, ill-defined)
- poor cosmetic result (vermillion boarder, nose tip, chin);
- BCC on site w high recurrence rate (nose, eye, scalp etc.);
- SCCs (most of them)
what is a shave excision
lesion is shaved off and heat applied to skin
2 indications for shave excision
usually benign lesions
1. chrondrodermatitis nodularis helicis - painful nodule which develops on ear due to side sleeping;
2. benign naevi;
2 contraindications for shave excision
- keratoacanthoma;
- melanomas!
what is an excision
removal of lesion with adequate margin
4 contraindications to excision biopsy
- no valid consent;
- INR too high;
- underpreparation with antplatelets/anticoagulatns;
- pacemaker check
indications for excision biopsy (2)
- suspected tumours;
- pigments lesiosn
5 factors to consider when determining suitability for RT
- type of lesion (is it radiosensitive e.g. BCC, SCC etc; whats the morphology e.g. nodular);
- site (areas where surgery may be difficult);
- previous radiotherapy;
- suitability of other treatments
- patient’s preference
what is micrographic surgery
excision of horizontal sections cut from the periphery of an excision specimin -> microscope needed
why is micrographic surgery used
to maximise the confidence of tumour clearance with minimal loss of surrounding normal tissue -> time consuming and expensive tho
when might Moh’s surgery (micrographic) be indicated
for tumours that are recurrent, in high risk zones and have agressive growth
what lesions are biopsies not done in
pigmented lesions - the area biopsied may not be a true representation of the whole cancer
when is chemo indicated (derm -4)
metastatic malignant melanoma; localised advanced mealomas (isolated limb perfusion); SCCs; rare BCCs
what targeted therapies are available for cancers (3)
- BRAF inhibitors
- MEK inhibitors
- C-KIT
adjuvant vs neo-adjuvant therapy
adjuvant - used after primary procedure to help reduced the recurrance of the tumour
neo adjuvant - used to reduce the size of the tumour prior to the primary tumour
example of adjuvant therapy
IF-alpha
