21 ABSITE_Skin and Soft Tissue- edited

All right. We're here with the Behind the Knife Ab Site Review doing skin and soft tissue. It's Kevin and Patrick here. We're going to dive right in and talk about what are the seven initiatives from the Surgical Care Improvement Project that were shown to reduce surgical site infections. Sure. First, we're going to avoid hyperglycemia.

Second, maintain normal thermia. Third, give prophylactic antibiotics within 60 minutes of incision. Four, we're going to select the appropriate antibiotics for the case. Five, we're going to discontinue antibiotic prophylaxis within 24 hours of surgery end time. Six, we're going to use a clipper for hair removal, not a razor.

And seven, we're going to remove urinary catheters within the first two post operative days. Yeah, so this is actually really high yield. This is very highly testable, so just make sure you know those and it is important in your daily practice also. Alright, so we're gonna dive right into a clinical scenario, Patrick.

So, you have a diabetic patient presenting with severe pain, erythema, and crepitus on their thigh after suffering a scratch a few days ago.

What are you concerned about? Yeah, so that's the perfect stem for a Necrotizing Soft Tissue Infection or NSTI. Yeah, so you definitely have to be worried about a Necrotizing Soft Tissue Infection, especially with the Crepitus in the stem there.

So how do we break down and kind of what are the definitions of Necrotizing Soft Tissue Infections? Yeah, it's important to recognize that Necrotizing Soft Tissue Infections represent a continuum of disease and so it all depends where that infection is. So Necrotizing Cellulitis is in the skin and subcutaneous tissue, whereas necrotizing myositis involves the skeletal muscle.

Most common infection here is group A strep. And whereas necrotizing fasciitis is an infection that results in destruction of muscle and fascia, this is the one that spreads quickly along those fascial planes. Okay, so let's dive a little closer into necrotizing fasciitis. Yeah. What are the three types?

Yeah, type one is polymicrobial. Type two is a monomicrobial again, most common being group a strep and type three is a grand negative marine organism. Most

frequently Vibrio volnificus. That was a great pronunciation. I know. I thought I was pretty impressed. So, all right, let's go into the presentation.

What, what are some of the things you see in these patients and what should raise red flags? Right? That early recognition is absolutely essential. Okay. So any patient with a soft tissue infection. Signs of systemic illness and certainly a concerning exam should go to the operating room for surgical exploration.

And on exam, the most common findings would include. erythema, edema, bullae especially a hemorrhagic bullae, crepitus and pain out of proportion to exam. Okay. One thing we talk about a lot when we're talking about necrotizing soft tissue infections is the Learnic scoring system. Yeah. What are the components of that?

L R I N E C. So this is lab based. Okay. This is not based on your exam. So, I'm going to riddle these off or rattle these off here. White blood cell count needs to be greater than 15, 000 CRP over 150. hemoglobin less than 13. 5. sodium less than 135

and glucose greater than 180. You add these up and if the score is greater than or equal to 6, this significantly increases the chance that the patient has a necrotizing infection.

Absolutely. So you don't need to have this score to have a necrotizing soft tissue infection, but it, Certainly raises red flags and you should have a higher suspicion if you do have these lab findings So we've talked about lab findings white count CRP low sodium high glucose Those are all really concerning things and I should mention too that that low sodium is kind of a unique thing And that's often what will show up on the question stem Is that that low so because you're wondering what well, this is a skin inflection like why are we including sodium in there?

That should definitely pique your interest. And that, and clinically, that seems to be how I've seen it also in real life. So it's, it's a, you know, it's there for a reason. So Patrick, we've talked about labs. So what, what about on imaging, would you be concerned? Yeah, so imaging is not required to make this diagnosis.

Again, if you're concerned, you go to the operating room and cut on that area. But oftentimes patients will have a CT scan. And if you

see gas in the soft tissue on CT scan, this is highly specific for a necrotizing infection. Okay. And so what's the treatment? Yep. Early surgical debridement. Okay.

Early surgical debridement of all that necrotic tissue, with plans to return to the operating room in short order, usually less than 24 hours. We're also going to give broad spectrum antibiotics, usually it's a combination. There's a few different types of antibiotics you can give, but in general, we give vancomycin.

To cover that MRSA and treat gram positive bugs. We give clindamycin for its anti toxin abilities. And then something like zosyn or unisyn to cover the rest. Alright, so let's kind of dive into some more skin and soft tissue stuff. I'm going to give you another stim here. You have a 45 year old female.

Dishwasher presents with two days of worsening pain, erythema and swelling to the lateral nail fold on the second digit of a right hand. Kind of, what are we thinking? These are always interesting abside questions because this is rarely something that we as surgeons, especially as general surgeons have to see, but I have seen this on the exam.

And so

we're worried about an acute peronechial infection here. In this case you would incise and drain the area and have to lift that edge of the nail bed up and give antibiotics. Yep. Absolutely. And what if you have a patient that, you know, keeps having recurrences of this and has kind of a chronic low grade infection?

Yeah. Again, for chronic infections, I don't think there's something that general surgeon be oftentimes involved with, but you can give topical steroids. And, and really in the question stem here, you mentioned this patient's a dishwasher. So you want to avoid frequent water submersions in the worst case scenarios, the nail plate can be removed for truly refractory cases.

Okay. Alright, let's stay within the hand and the finger. Let's talk about a felon. What is it and how do you treat it? Yeah, what a, what a great name. So this is an infection of the fingertip pulp, and in this case we're gonna do a vertical incision. This is, the question would be horizontal or vertical incisions, A vertical incision to to drain that area and to avoid risk of damaging the neurovascular structures at the fingertip.

Okay.

And so now we're going to stay in the skin and soft tissue, but move to sort of the axillas and the groins. Let's talk about hydranidous supativa. What puts you at risk for this? What is this? Yeah. So this is a. condition and it's chronic recurring infections of the apocrine sweat glands. Okay.

And again, you'd mentioned most commonly it presents in the axilla, inframammary folds and in the groins and risk factors include smoking. Obesity and females are more likely to have HS. Okay. And Yeah, this is a really tough condition. So kind of how do we break it down and what are the treatments for the different stages?

Yeah, and I think this is probably the testable component. So there are it's the Hurley stage that we use to describe HS severity. There's stage one, there's stage two and stage three. On stage one there are localized abscesses without sinus tracts and minimal scarring. Treatment here are lifestyle modifications and topical or oral antibiotics.

Early stage two refers to recurrent abscesses with sinus tracts and scarring, and there is healthy skin separating areas of involvement, so it's not continuous. In this case, you can consider antibiotics, but also those TNF alpha inhibitors and if severe enough, excision. So, remember stage two, there's separate areas of, of healthy skin between these diseased areas, and this is when we kind of rope in this T, those TNF alpha inhibitors.

And then stage three is severe, diffuse disease, everything's interconnected, sinus tracts, scarring. Et cetera. And in this case you're really thinking about surgery. So wide excision with or without split thickness skin grafting. Okay. Yeah. So if it's very localized at stage one, you're gonna do the lifestyle modifications, keep the areas dry, et cetera.

Topical or oral antibiotics. Stage two is when you're having these recurrent abscesses, but there's still some healthy skin in the area. So the antibiotics and the TNF alpha inhibitors and some excision and then stage three is where you get to the real big. Wide

excision of the skin grafts. So, okay, well, I think we've covered that.

So let's go to another tough problem pilonidal disease. Who's at risk for this? Where do you see this? Yeah. So most commonly presents in folks in their teenage years or twenties or thirties much less frequently in older folks, more common in males than females, more common in folks with a greater BMI.

And often, but not always, in patients who have thick body hair. And this is diagnosed on, on history and physical exam. Okay, patients will have swelling, intermittent drainage, perhaps a sinus track at the supergluteal, at the gluteal cleft right over the tailbone there. And in general you know, we'll see these patients in clinic quite often.

And for the test, you know, I think you're going to get questions about treatment and you really got to think about how severe the disease is, how it affects the patient's life, and how many times they've presented. Are they getting routine INDs? Have they already had an excision procedure performed?

Are they really early on?

Because in terms of treatment, you're going to want to start with those simple recommendations like. Weight loss, keep the area clean and dry, use antibacterial soap, and really importantly is that hair removal strategies. So keeping the area free of hair as that tends, or we believe that's one of the main parts of the pathogenesis of this is hair getting into these tracts and and and crypts.

Yeah, so prevention is key in pilonidal disease as it is in many surgical conditions. Really keeping the hair out of there, losing weight, keeping it clean. All these things can really help prevent recurrences of these things. But sometimes even with all of that they continue to have issues. So how do you manage an acute infection and then kind of, what are your approaches if with these kind of smoldering problems?

Yeah. And going back on that, I think on the exam, you're going to be asked, you know, the answer may be hair, hair removal strategies as a treatment or when they present infected. would be this incision and drainage. So you talked about treatment. If they're infected, it needs to be

incised and drained, plus or minus antibiotics and you're not going to do any formal treatment while things are infected.

So an infection has to clear so don't get that confused on the exam. You're not going to do a big excisional procedure unless the infection's gone. And then next there's, there's a lot of different ways to approach pilonidal disease and you start with some of the simpler things like. pit picking and curatage of these tracks, removal of hair, et cetera.

Some folks recommend using phenol or RFA ablations to treat these areas but on the exam, they're going to likely be asking about excisional procedures, including things like a cleft lift procedure, or simple excision with healing by secondary. Alright, let's dive into skin cancers. Alright, let's start off with basal cell carcinoma.

Tell me a little bit about that, Patrick. Yeah, this is the most common skin cancer. You will see raised, waxy, well circumscribed lesions with rolled edges. And what's the treatment? Yeah, for most of these really all of

these, wide local excision, and then the margins need to be at least 4 10mm margin for basal cell carcinomas.

Yeah, and if you don't have these images popping into your brain of kind of what a basal cell, what a squamous cell, what these things look like, I would do a Google search, a Google image search, just to kind of get the kind of classic images in your head. I think it would be really helpful. Sometimes they will show you images on the test.

So let's go to the next one, the squamous cell. Yeah, second most common behind basal cell. And the, this is, and actually this is a good question. So what's the precursor lesion? That's actinic keratosis. So that is a pre cancerous lesion. Yes. And so what does it sort of look like clinically? Yeah, ulcerated skin with, with raised, oftentimes irregular borders or edges.

Okay, and then what's the treatment? Again, wide local excision with four to ten millimeter margins. Same as basal cell. Right. Okay, Patrick. What can you tell me about Merkel cell carcinoma? Yeah, these are rare and most important for the test. They arise from neuro endocrine cells

Yeah. And so how did they present?

Yeah. So these are rapidly growing firm red or purple nodules without any ulceration. Okay. And then how do you stage these patients? Yeah. Pet scan. Yeah. And what's the treatment? Okay. So you want to resect with one to two centimeter margins and in this case perform a sentinel lymph node biopsy and you're going to give adjuvant radiation.

If you're greater than stage two, which is a greater than two centimeter lesion and for stage three, which includes any size lesion with lymph node metastasis, yeah. This one is, that is also a testable portion. It's one of the few skin cancers that you give adjuvant radiation for. They are radio sensitive and so this is one of the few kind of skin cancers that radiation therapy is a big part of the management.

So just keep that in mind. Alright, so let's do melanoma now. Common? Yeah. What are, what are the kind of classic signs, warning signs of melanoma? Yeah, you gotta know this. So asymmetry irregular border. Color or purplish or dark color, diameter of greater

than six millimeters and evolution or change in the lesion.

So remember that's a b c d e. Great. And what's the best way to diagnose this? A full thickness biopsy. Definitely. And all right, let's talk quickly about the margins as far as the depth of the tumor goes. Yeah. So remember the Breslau depth is a depth of tumor extension. Your excisional margins are based on that tumor depth.

So if you have melanoma in situ, recommended margin is 0.5 to one centimeters. If your breslow is less than one millimeter, margin is one centimeter. Breslow, one to two millimeters margin is one to two centimeters, and a breslow greater than two millimeters. Margins are two millimeters, or excuse me, two centimeters.

Okay, great. And so which size of this do you need to do your sentinel lymph node biopsy, right? This is a high yield question. So we perform sentinel lymph node biopsy for melanoma for any lesions with a Breslau depth of 0. 8 millimeters or greater and in certain

melanomas with high risk features like ulceration.

Okay. So this can get complex, but In general, what do you need to do if you have a positive sentinel lymph node biopsy? Right, and there's a specific trial, MSLT2, that helps answer this question. And MSLT2 found that serial clinical examinations within the nodal basin using ultrasound is safe compared to completion lymph node dissection.

Okay, great. So now what about the patients that present with metastatic melanoma? What medical options do we have for them? Yeah, and these are increasing and important, again, testable questions. So one is Pembrolizumab, which is a monoclonal antibody against PD 1, and this has been shown to increase long term survival in patients with metastatic melanoma.

Another category would be the CTLA 4 antibodies, which is used in patients with advanced stage disease. Great.

Okay. So what if about if you have a subungual melanoma, right? So underneath the fingernail so whether it's a finger or toe, you're gonna perform amputation of that digit. Okay. And what about the sentinel lymph node biopsies in this?

Yeah. So if the Bresl depth is greater than one millimeter for a subungual melanoma, you will perform a sentinel lymph node biopsy. All right. Great. So let's dive into lymph node dissections. So tell me when we're talking about a superficial inguinal lymphadenectomy What exactly are these nodes? Where are they located?

Yeah, so superficial inguinal lymph node dissection refers to the femoral triangle Okay The femoral triangle is made up of three borders the superior border is inguinal ligament medially the adductor the sartorius Okay. And now how about the full on deep lymphadenectomy of the inguinal area? Right.

This is a little bit tougher. So I'm going to give multiple borders cause it's, you know, more of a three dimensional type space. So we're going from the bifurcation of the common

iliac artery to the inguinal ligament, immediately to the bladder and ureter laterally to the pelvic sidewall. And deep to the obturator nerve.

Yeah, so basically everything in that lower pelvis. Okay, so let's do our quick hits here. What is the treatment of herpetic Whitlow? Yeah, so observation and avoiding contact with these lesions. We're not going to perform IND as this can cause systemic spread of the virus interestingly. So how about treatment of striae atrophicae or stretch marks?

Reconstruction. Excision of that area. Yep. Okay, what is the most common cause of lymphangitis? Streptococcus pyogenes. Most common cause of... Can you help me with that word? Iris syphilis. Thank you. Group A strep. And these are raised lesions with sharply demarcated borders. What are the two main types of necrotizing fasciitis?

Type 1 is polymicrobial, type 2 is monomicrobial, usually group A strep. Okay, and what is the most

common bacteria associated with Fournier's gangrene? Right, Fournier's being essentially necrotizing infection in the perineum, E. coli, Klebsiella, and Enterococcus, so stool bugs. Okay, so you did a biopsy of a melanoma and it came back at 8 millimeters tumor depth.

What kind of margin do you need for this? One centimeter. Great, well that wraps up skin and soft tissue. Let's drive on. We survived.