As a primary care provider, nurse practitioner or PA, are you interested in learning more about how you can have skin concerns in your practice co-managed with an 'on-demand' dermatologist? Learn more here.
If you are a patient seeking a first or second opinion from a dermatologist on a spot mole or rash of concern, you can access a dermatologist via your local primary care provider or urgent care clinic. Find our list of partner locations here.
How should I decide between skin biopsy techniques?
The first step in deciding which biopsy type to use as a primary care provider is to consider what your goals are regarding the pathology report. Identifying the condition based on anatomical structure, indications, and contraindications in order to outline the clinical significance of the biopsy is key.
Shave, (b) punch, (c) excision
What are the parameters for using a punch biopsy?
The punch biopsy uses a cylindrical blade that provides greater depth, perfect for inflammatory dermatoses or deep pathologies. If it is a rash, you must distinguish if the pathology is more likely in a new lesion as well as more evolved lesions.
If the skin findings in or to diagnose the rash are deeper in the dermis, then you will perform a punch biopsy to include the deeper aspects of the dermis or even the subcutaneous tissue. For instance, if you are ruling out vasculitis, you need to get tissue that is deeper in the dermis, so a punch biopsy will be more likely to give your pathologists the tissue needed to evaluate the tissue.
What are the parameters for using a shave biopsy?
If you are trying to diagnose a superficial lesion as a primary care provider with epidermal changes such as a basal cell carcinoma, then a shave biopsy is appropriate, but make sure you include at least the superficial dermis. A common pitfall with shave biopsies is to perform a biopsy that doesn’t include superficial dermis, therefore not being able to rule out an actinic keratosis vs. an invasive squamous cell carcinoma. This can result in a report that relates that there is a hypertrophic actinic keratosis that extends to the base, therefore squamous cell carcinoma cannot be ruled out. If you are ruling out an atypical nevus, you can use both a shave or punch technique, but to understand that you need to target the 2mm into the dermis in order to obtain an accurate reading.
What are the parameters for using an excisional biopsy as a primary care provider?
If there is a concern regarding a deeper pathology such as a panniculitis, then an excisional biopsy will be indicated or a deep 6-8mm punch biopsy to obtain enough deeper tissues to determine the diagnoses. If the base is transected, or cut across, then accurate staging is difficult.
How do you biopsy pigmented lesions, like cancerous moles or liver spots?
For pigmented lesions, ideally you want to remove all the obvious pigment with a 2mm margin and at least 2mm in depth. If the lesion is quite large or on cosmetically sensitive areas you can consider a DermTech tape stripping option. There’s also the option to remove the darkest or thickest/most irregular appearing part of the lesion, realizing that the best removal would allow for the dermatopathologist to see the architecture of the full lesion. If you are concerned about a pigmented lesion, we recommend sending your specimen to a board-certified dermatopathologist. These lesions can be quite difficult and are perhaps your highest concern of both an over- and under diagnosis. If you are not able to use a dermatopathologist initially but have concerns about a pigmented lesion it is reasonable to ask for a second opinion. We can assist in coordinating this for you through Modern Ritual Health if you need our support.
Examples of pigmented lesions (https://doi.org/10.1016/j.eswa.2016.05.017)
How to address scarring from a punch biopsy as a primary care provider:
This may be where you would want to refer out as any removal will result in a scar. There have been studies that demonstrate that you do not need to suture 3mm or smaller punch biopsies, however for hemostasis and facial areas, you typically will place one suture. As mentioned above, for pigmented lesions, particularly in cosmetically sensitive areas, The DermTech tape stripping option is a reasonable screening option. Please see the link here to learn more.
DermTech stripping method (https://doi.org/10.1111/bjd.19760)
Whether you are a family doctor, a nurse practitioner with 3 or 30 years of experience, it's always helpful to have the most up-to-date support in treating patients with potentially concerning skin lesions, rashes and moles.