From the Guidelines
A punch biopsy is performed by first selecting and preparing the site, followed by administering local anesthesia and using a punch tool to obtain a tissue sample. To perform a punch biopsy, the area should be cleaned with an antiseptic solution like chlorhexidine or alcohol 1. The next step is to administer local anesthesia using 1-2% lidocaine with epinephrine (typically 1-5 mL) via a 30-gauge needle, injecting into the dermis beneath the biopsy site 1. Once the area is numb, hold the punch tool (typically 2-6 mm in diameter) perpendicular to the skin surface and apply downward pressure while rotating the punch between your fingers in a back-and-forth twisting motion until you reach the subcutaneous fat 1. The punch biopsy is a valuable diagnostic tool because it samples all skin layers from epidermis to subcutaneous fat, providing comprehensive tissue for pathological examination while creating minimal scarring 1. Some key considerations when performing a punch biopsy include:
- Selecting the appropriate biopsy technique based on the clinical characteristics of the suspected tumor and patient-specific factors 1
- Ensuring the biopsy specimen size and depth are adequate to provide the recommended clinical information and pathology report elements 1
- Considering the use of other diagnostic techniques, such as dermoscopy, to improve diagnostic accuracy and direct optimal tissue sampling 1
- Avoiding partial removal of naevi for diagnosis, as this can lead to incorrect diagnosis and unnecessary anxiety 1 For hemostasis, apply direct pressure for 5-10 minutes or use aluminum chloride, silver nitrate, or electrocautery for persistent bleeding 1. Close larger defects (>4 mm) with simple interrupted sutures using 4-0 or 5-0 non-absorbable material 1. It is essential to prioritize the patient's comfort and safety during the procedure, and to obtain informed consent before performing the biopsy 1. The most recent and highest quality study on this topic is from 2018, which provides guidelines for the management of cutaneous squamous cell carcinoma, including recommendations for biopsy techniques 1. Overall, a punch biopsy is a useful diagnostic tool that can provide valuable information for the diagnosis and treatment of skin lesions, and should be performed with careful attention to technique and patient safety.
From the Research
Punch Biopsy Procedure
- The punch biopsy technique involves the use of a circular blade that is rotated down through the epidermis and dermis, and into the subcutaneous fat, yielding a 3- to 4-mm cylindrical core of tissue sample 2.
- To perform a punch biopsy, the skin should be stretched perpendicular to the lines of least skin tension before incision, resulting in an elliptical-shaped wound that can be easily closed with a single suture 2.
- Properly administered local anesthesia, such as lidocaine, usually makes the procedure painless 2, 3.
- It is essential to handle the obtained specimen with caution to avoid crush artifact, which can affect the quality of the tissue sample for microscopy 4.
Indications for Punch Biopsy
- Punch biopsies are useful in the work-up of cutaneous neoplasms, pigmented lesions, inflammatory lesions, and chronic skin disorders 2, 5.
- The decision to perform a punch biopsy should be based on the type of skin lesion and the need for histopathologic information to diagnose the condition definitively 6.
Considerations for Biopsy Techniques
- Different biopsy techniques, such as shave, saucerization, punch, fusiform, and subcutaneous nodule biopsies, may be used depending on the type of skin lesion and the required depth of tissue sample 6, 5.
- The choice of biopsy technique should take into account the potential pitfalls and complications, such as tissue trauma and inferior quality of the tissue specimens, to ensure a cosmetically acceptable result 6, 4.