I'm Carrie Wanet, and I'm going to be talking about wound biopsy in relation to wound care and the importance of getting histopathology in certain circumstances. I have no relevant conflicts of disclosure, and I'm coming from Medical College of Wisconsin where I practice as both a dermatologist and a dermatopathologist. A biopsy is important when we're evaluating a wound for several different reasons. One is to obtain a diagnosis when that's uncertain. Two is to exclude certain diagnoses when we're considering therapeutic options for patients. The third is to evaluate for an infection, which is oftentimes in the differential diagnosis when we evaluate for wounds. And a tissue biopsy is extremely important as opposed to a superficial swab, because a superficial swab may demonstrate that there are organisms or colonization of organisms at the top, but not a true deep infection. And then finally, when we think about wounds, one of the differential diagnoses we think about is a vasculitis, and a direct immunofluorescence can be important in evaluating for certain types of vasculinities. When we think about a wound, a biopsy may not be necessary in all circumstances, but a biopsy is extremely important for certain situations. One in any ulcer that is considered atypical, where the etiology isn't immediately apparent, would be really, really important. The second is that if it ulcers for the entity with which you're thinking about, for example, being a stasis ulcer, is not healing at the rate that you would expect, then an alternative or secondary diagnosis may also need to be considered. The biopsy should also be considered if there's any rapid growth or change, or something is newly onset and it is rapidly evolving. And then finally, if you have just have a clinical suspicion that something else is going on, if something just doesn't seem quite right, then obtaining a biopsy can be really important to either help support the diagnosis that you're considering or exclude other entities. When we obtain the biopsy, the location, as in everything within dermatology or anything that we evaluate, is really important. In addition, the way we do that is also really important to make sure that the patient is comfortable throughout. We want to make sure that appropriate lidocaine is used for anesthesia. In some circumstances, we want to make sure a wound is painful at baseline, and so making sure that the patient is most comfortable as we're obtaining those biopsies is really, really important. We want to perform at the edge of the wound where inflammation or purpura is present to get the most representative histopathology. One could also biopsy any surrounding purpura that may be present. Biopsying the center of the wound is going to be least helpful because it is going to show a broad ulceration. And when you have a broad ulceration underneath that, histopathologically, there could be a lot of things going on. And we won't know that if those changes, such as a vasculopathy or vasculase, are secondary to that ulceration or the primary reason. So really getting the edge or the purpura around or inflammation around an ulcer or wound is really important for histopathology. A tissue culture also, in most circumstances, should be obtained because I would argue that most ulcers, in the differential diagnosis of most ulcers, infection is really high in that list. And a tissue culture is also obtained. And getting some of that center portion and the lower circle that's shown in the image can be helpful because you get some of that to sort of see if there are organisms within that ulcer or extending out. A full-thickness biopsy is important, including the subcutaneous tissue. This can be hard when that tissue at the edge is really friable, so using at least a four-millimeter punch biopsy can be really important to get a large representative piece of tissue. And then when you're done evaluating the wound, using gel foam to close that wound may be more helpful than suturing because of that friable nature of that wound that may be present. The other thing that's really important when we think about the obtaining of these biopsies, when we're thinking about tissue culture specifically, is you want to cleanse the wound or the area that you're getting with either chlorhexidine or betadine to ensure that you're getting rid of organisms that may be colonizing the area. You really are most interested in getting the deeper portion of that, and so making sure you cleanse the area to remove some of the superficial contamination can be really helpful. When we think about the diagnosis of wounds, we want to, and the histopathology that's present, we approach this from a dermatopathology perspective on whether or not a malignancy is present or not, whether or not inflammation is present or not, and what that inflammation could be. And sometimes knowing just what something is not can be very helpful. So if you're looking at a wound and an ulcer and you're not sure what's going on and there's malignancy present, such as an invasive or ulcerated sclerosal carcinoma, an ulcerated lymphoma, other entities, histopathology can be very, very helpful. And getting that full thickness biopsy can also be really helpful to evaluate for other entities like perineural invasion, lymphovascular invasion, et cetera. When something is not a neoplasm and more of an inflammatory diagnosis, the definitive diagnoses can sometimes be difficult because there can be several different entities going on. However, the histopathology description that your pathologist provides is equally important because it could tell you what is not present, if there is not vasculitis present, if there's not an infection present in these evaluations, et cetera. And then special things are probably the norm in the evaluation of these, where we evaluate for bacteria using a Gram stain, fungus using a PAS or a GMS stain and evaluation of a typical mycobacteria using AFB. And it's important to do this both on histopathology, as well as in tissue culture, because there have been several studies that show that the organisms may show up in one of the specimens but not the other. So for example, you may see organisms on histopathology and it may not grow in culture immediately, or you may need other special techniques. Similarly, you may not see the organisms on histopathology, but in tissue cultures, they grow because the number of organisms can be very few in these circumstances. When we think about the histopathology of atypical wounds, oftentimes some of the things we're trying to differentiate between are pyoderma gangrenosum and infection. And in both of these, the histopathology can look similar, where there's acute inflammation with many neutrophils and there can be focal granulomas inflammation. And so that histopathology is not specific. And in general, pyoderma gangrenosum is a diagnosis of exclusion, and so special stains and tissue culture need to be performed in these circumstances to exclude a diagnosis of infection before providing the definitive diagnosis of a neutrophilic dermatosis such as pyoderma gangrenosum. So that's very important to consider. Other entities that we think about when we get a biopsy from an ulcer and atypical wound would be vasculi and vasculopathy. The difference between these and vasculitis is you get actual inflammation, necrosis, breaking up of the white blood cells called leukocytic lesion, extrepidated blood cells and a vasculitis. And in a vasculopathy, you get more plugging of those vessels with fibrin with more limited inflammation. The location of the biopsy is extremely important because underneath an ulcer or wound, vasculitis and vasculopathy can be present secondary to that ulceration, not because that is the causing it, but because it is right underneath it. And so the location of this and the evaluation and the presence or absence of vasculitis or vasculopathy adjacent to that ulcer under normal skin is extremely important. In addition, being able to evaluate the depth of it and other things going on can be really critical. Here's a, in this previous biopsy or previous section, we're starting leukocytic, leukocytic clastic vasculitis with that focal ulcer and the necrosis of the small vessels with inflammation. We feel more confident in this particular case that this is a vasculitis because there's not sheer inflammation underneath it, but really vascular centric inflammation. So that's very helpful. In this particular occasion, this is a case, there's this example of vasculopathy where you get focal epidermal necrosis with red blood cell extravasation and the fibrin deposition. What's unique about this compared to the last one is you get very minimal inflammation. And so this vasculopathy is causing the overlying changes that are present. So perhaps one of the most common things that we will find out from dermatopathologists from chronic wound is more nonspecific histopathology, where we see some dermal fibrosis with mixed acute and chronic inflammation. So you have some neutrophils, some lymphocytes, some plasma cells, some histiocytes, and it's really hard to say exactly what it is. And so this could be that this could be caused by a multitude of entities. And so it's important to exclude infection, it's important to clinically evaluate and decide what it is. And in this particular circumstances, we may have excluded some of these things, some of these entities based on histopathology. However, knowing the location of the biopsy and any prior treatment of the ulceration is really important because if the patient is on systemic steroids or other anti-inflammatories, then the acute inflammation may not be as prominent in this particular case. And the treatment may have impacted what the histopathology looks like. So knowledge of those is important. We may put a disclaimer of this, of whereas the age of the lesion, the location and prior treatment can impact what is going on. A repeat biopsy and or review of histopathology or discussion with pathologists may be important in multiple circumstances. Sometimes deeper level sections or more sections of a biopsy can be obtained if certain entities be evaluated or it may be that the first biopsy did not demonstrate because of treatment or because of location, the entity that was expecting. So if there is continued rapid change or if it's clinically warranted or if you feel like there's a ClinPath disc correlation or a ClinPath correlation is lacking, then a repeat biopsy in a new area or a couple of biopsies may be necessary to actually get the diagnosis. In this particular example, perhaps the initial biopsy was done at the edge of the wound indency, but now there's more purpura that is more superficial in that entity. And then in those circumstances, getting a biopsy in those areas may be critical. These are some references that were used for this. And I thank you for your attention in relation to the importance of histopathology and biopsy of these wounds. And thank you so much.

wound biopsy

diagnosis

infection evaluation

immunofluorescence

histopathology