Skin Flashcards
What is the implication of crepitus?
Gas in the tissues: presence of gas-forming organisms
What are the risk factors for NSTI?
- Decreased immunity
- Decreased tissue perfusion
Ex: DM, malnutrition, IVDU, obesity, chronic alcohol use, CLL, chronic steroid use, renal failure, PAD, cirrhosis - Traumatic extremity wounds with contamination OR post surgically
What is the implication of bullae?
Partial tissue death within layers of skin that allow for collection of fluid between layers
What is implication of violaceous skin?
Violet or purple discoloration 2/2 ischemia
What are the hard signs of NSTI? What percent of patients have them?
Hypotension Crepitus Skin necrosis / bullae Gas on x-ray < 50%
How to distinguish between cellulitis and NSTI?
- Difficult: need high level of suspicion
- Use Lab Risk Indicator for Nec Fasciits (LRINEC) to help distiguish
What components are in the LRINEC for NSTI?
CRP, WBC (high), Hb, Na (low), Cr, glucose
Why is it important to distinguish between cellulitis and NSTI?
Tx: cellulitis is ABx and NSTI is emergent surgical debridement
What is the spectrum of NSTI (location)?
Skin/SubQ: necrotizing cellulitis
Fascia: necrotizing fasciitis
Muscle: Necrotizing myositis
What are the 3 types of NSTI?
Type I: polymicrobial
Type II: Group A Strep
Type III: Clostridial myonecrosis: Clostridium perfringens
What other term is used for necrotizing myositis?
Gas gangrene
What is the implication of culturing Clostridium septicum from the wound?
- Can lead to gas gangrene
- Associated with occult malignancies (colon cancer)
What is the term for NSTI that involves scrotum/perineum?
Fournier’s gangrene
What are initial management steps of NSTI?
IV fluids
Broad spectrum IV AB
Aggressive surgical debridement
How do you determine how much tissue to debride in NSTI?
Take all sub tissues that show any evidence of infection: must see healthy bleeding tissue! Cannot leave any borderline tissue
What if extensive muscle necrosis is found during surgery for NSTI?
Amputation may be necessary
What are intraoperative findings that confirm NSTI?
- Murky fluid (dishwasher)
- Gray discoloration of fascia
- Lack of bleeding from fascia
- Fascia may separate from muscle too easily w/o normal resistance
What is the role of 2nd look operation?
Schedule 24 horus after initial debridement to make sure infection is truly gone (may need to do several times)
What if NSTI is highly suspected but diagnosis is uncertain?
Do surgical exploration
Is imaging beneficial for NSTI diagnosis?
- Plain xrays: may show gas
- CT: can show asymmetric fascial thickening, gas tracking along fascial planes or abscess
What is mortality risk of NSTI?
25%
What is an emerging therapy for NSTI?
Hyperbaric oxygen: reduces mortality
How can we differentiate melanoma from a benign nevus?
ABCDEs: Asymmetry Border irregularity Color change Diameter > 6mm Evolution
What risk factors for skin cancer are common to SCC, BCC and melanoma?
- Excess exposure to UV light, especially UVB
- Immunosuppression
What factors during childhood/teen years are associated with increased risk of skin cancer?
Blistering sunburn
Tanning salon
What does hair growth on a skin lesion suggest?
Benign: melanomas destroy hair follicles
What is the ugly duckling sign?
Any skin lesion that looks out of place/different = ugly duckling: should biopsy!
What is important about chronic skin inflammation when evaluating from skin lesions?
Risk factor for SCC: can develop in chronic open burn wounds, chronic venous ulcers, and long standing skin infections
What to do with chronically non-healing wounds?
Biopsy: rule out malignancy
What areas of the skin are melanomas are most likely to occur in non-white ethnicities?
Af Am, Asian and Hawaiian populations: occur on areas of non exposed skin with less pigment: palms, soles, mucous membranes and nail regions
What is the most common site of melanoma in men vs. women?
Men: the back
Women: the legs
What is the most common site of digital melanoma?
Great toe: amputate and sentinel nodes
Does the regular use of SPF protection reduce the risk of skin cancer?
Yes: SPF 15 reduces the risk of SCC and melanoma by about 50%
Where does melanoma arise from?
Melanocytes
What is the order of most common to least for skin cancer?
BCC > SCC > melanoma
What is the most common precancerous skin lesion?
Actinic keratosis: rough scaly epidermal lesion in an area of chronic sun exposure
What is Bowen’s disease?
squamous cell carcinoma in situ: well defined erythematous plaque covered by adherent scaly yellow crust (does not metastasis)
What is the 5 year survival of melanoma > 4.0mm thickness?
50%
What is the 5 year survival of melanoma < 0.75mm thickness?
95-100%
What is the metastatic risk of BCC, SCC and melanoma?
BCC: no mets usually
SCC: do metastasize, but less likely than melanoma
Melanoma: to skin > lung, liver, brain and bone
What is the most common metastasis to small bowel?
melanoma
What is superficial spreading melanoma?
Most common type: long horizontal growth phase before vertical (better prognosis)
What is lentigo melanoma?
Lentiginous proliferation: tumor remains at the junction (best prognosis)
What is acral lentiginous melanoma?
In subungual, sole or palm location, common in groups of color
What is nodular melanoma?
Worst prognosis: rapid vertical growth and increased metastatic potential
Which type of melanoma is not related to UV light exposure?
Acral lentiginous
How do we stage melanoma?
Breslow depth: vertical height of melanoma
In a suspicious skin lesion, what is the next step in management?
Small: excision biopsy
If larger: incisional biopsy (punch biopsy)
Once diagnosis of melanoma is established, what additional studies should be done?
CXR
CBC
LFTs
LDH: prognostic indicator, may demonstrate liver mets
What if palpable lymph nodes are present in setting of melanoma?
CT scan or chest, abdomen pelvis
PET scan
What are poor prognostic indicators for melanoma patients?
Thicker lesions
Ulceration
Location on trunk
Male gender
What is primary treatment for BCC/SCC skin cancers?
Excisional biopsy
Can use Mohs for tissue sparing in cosmetically sensitive areas
What type of surgical margins are needed for BCC vs. SCC?
BCC: 3-5mm
SCC: 5-10mm
If margins are positive, what is necessary in skin cancer?
Must re-excise to clear!
How do we manage melanoma surgically?
- Diagnose via punch or excision biopsy
- Re-excise for clear margins based on Breslow depth
- Selective SLNB based on Breslow depth
Who gets lymph node dissection with melanoma?
Clinically palpable disease
OR positive sentinel lymph node biopsy
What is the follow-up protocol for melanoma?
- PE at 3-6 month intervals for first 3 years
Do we use Mohs for melanoma? Why or why not?
No: difficulty with preparing frozen sections for visualization of melanocytes (need immunohistochemial staining)
When we suspect melanoma, can we use shave biopsy?
No: cannot assess depth of lesion
What 2 types of melanoma do not follow ABCDE rules?
Nodular: berry like lesion that grow vertically
Amelanotic melanoma: have no pigment
