When Should You Biopsy?
When facing a skin condition or wound that can be challenging to identify, a biopsy can be an invaluable tool in illuminating a path for diagnosis and treatment. This author details the protocol for when to perform a biopsy and which technique to choose for which clinical presentation.
As many skin conditions are clinically difficult to differentiate, a biopsy provides a histopathologic diagnosis that ultimately helps to support the treatment plan. It can also clarify the skin disorder when a treatment plan is not yielding the appropriate results. Lastly, a biopsy can be curative or even life saving if one excises the lesion in toto or when the biopsy helps identify a treatable malignant diagnosis. Ultimately, a biopsy can both complement and confirm the diagnosis.
Over the last few years, our profession has been exposed to biopsy workshops and lectures at numerous conferences. The techniques of performing shave, punch and incisional/excisional biopsies are fairly straightforward, but when you return to the office on Monday after that weekend conference, are you confident which lesions to choose and when to perform those techniques?
Accordingly, I would like to present a basic guideline you can use in daily practice when confronting challenging wounds, rashes and pigmented lesions.
Biopsies For Wounds: What You Should Know
Understanding the etiology of a wound is imperative in its management. Besides establishing a diagnosis, one of the most important reasons for performing a wound biopsy is to rule out the presence of malignancy. Chronic wounds that are the site of longstanding inflammation, such as from a burn or a sinus tract, may transform into malignant lesions. A squamous cell carcinoma arising in an area of an old scar, burn or wound is termed a Marjolin’s ulcer and occurs more often in the lower extremity.1 This transformational process may take anywhere from one year to 25 years to develop.2 In addition, lesions that are malignant (both de novo and metastasis) may present as wounds and one can easily misdiagnose them as chronic wounds.
When should you biopsy a wound?
• The treated area has been present for over three months and has not responded to standard treatment.
• The wound bed has become exophytic and hypergranular.
• In the absence of infection, the wound has become painful, malodorous and the amount of drainage has changed.3
For the clinician who works in a wound care center, consider the scenario of a patient who presents with a painful medial leg ulcer that has been present for 25 years, has received treatment for a venous stasis ulcer and has not seen any changes with the ulcer. This is suggestive of performing a biopsy during the first visit. After performing a thorough history and physical, the clinician may perform a wound biopsy to rule out malignancy, but also to determine if the wound has an inflammatory basis. Painful leg wounds, such as pyoderma gangrenosum, arising in the presence of rheumatoid arthritis, inflammatory bowel disease or hematological disorders may not have specific histopathologic identifiers in their chronic state. In the case of pyoderma gangrenosum, this diagnosis of exclusion can be just as helpful to facilitate an appropriate treatment course for the patient.
Other inflammatory based ulcers include those that occur with vasculitis, anticoagulant syndromes and drug reactions. In those cases, it might be helpful to do a second biopsy and send the sample for direct immunofluorescence, which will help in elucidating the underlying cause.