Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Biopsy Techniques
Key Points
-
Proper biopsy is critical in the diagnosis and management of skin cancers.
-
Melanocytic lesions should be removed with an excisional biopsy where possible in order to obtain the most accurate diagnosis and prognostic factors although there is no evidence that an incisional biopsy adversely affects prognosis.
-
Non-melanocytic lesions can be removed with a shave biopsy or other incisional techniques.
Introduction
The biopsy is a critical start to the diagnosis of skin cancer. It is ‘the process of removing tissue from patients for diagnostic examination’. Fortunately, the accessibility of the skin simplifies the biopsy process relative to other organ systems. Experienced clinicians can often identify skin cancers during physical examination using both visual and tactile clues. Nevertheless, a properly performed biopsy is paramount to the diagnosis and eventual management of the skin cancer. The numerous biopsy techniques available to a clinician include: excisional, incisional, shave, saucerization and punch. Each of these modalities serves a different purpose and clinicians who manage skin cancers should understand and master all of them. Correctly biopsying pigmented lesions illustrates this importance, as there may be significant ramifications beyond the initial diagnosis of melanoma. Factors such as depth of invasion, ulceration, microsatellitosis, angiolymphatic invasion, and mitotic index can impact prognosis and proper management. The decision to implement additional prognostic and therapeutic techniques such as sentinel lymph node biopsy and systemic adjuvant therapies is often determined by the results from the initial biopsy. Therefore, procurement of an adequate specimen for presentation to the dermatopathologist is critical to assure a correct and complete diagnosis. Conversely, aesthetic outcomes should be considered since many suspicious lesions are in fact determined to be benign. This chapter reviews the decision-making process and discusses in detail the biopsy techniques and rationales for their use.
Decision–making process
There are many different types of skin cancers which are frequently divided into two categories: melanoma and non-melanoma skin cancers. This division stems from the relative difficulty and controversy surrounding the histologic diagnosis of melanoma. The controversy arises as similar-appearing melanocytes, the pigment-forming cells of the skin, can be found in a benign nevus, atypical or dysplastic nevus, and invasive melanoma. Since the prognosis and management of melanoma is based primarily on the Breslow depth of invasion, an adequate deep margin is necessary in the diagnosis. Thus, a proper initial biopsy is critical to correctly diagnose and characterize melanoma. This type of information is best obtained in the initial biopsy. There is more flexibility in the type of biopsy technique chosen for diagnosis of non-melanoma skin cancers, with respect to important factors such as location, appearance, and the size of the lesion.
Types of biopsies
An excisional biopsy refers to en toto removal of a suspicious lesion. This is performed with a margin (as defined below) of clinically normal tissue. It is the preferred method of removing a pigmented lesion for histologic interpretation.
An incisional biopsy is used to sample only a part of a suspicious lesion for histologic evaluation. It is an appropriate method to biopsy a suspicious non-melanoma skin cancer.
Shave biopsy refers to a shallow removal of a lesion at a depth confined to the dermis. It can be performed by a scalpel, a Dermablade®, a razor blade, or scissors.
A saucerization is a biopsy which occurs through viable dermis into subcutaneous fat. It is performed by angling a scalpel at approximately 45 degrees to the skin and removing a disc of tissue, including all or part of the suspicious lesion, well into the subcutaneous fat.
Punch biopsy refers to the use of a sharp circular instrument to remove tissue well into the subcutaneous fat. It is usually sutured.
Fusiform ellipse allows for full-thickness removal of the suspicious lesion, as well as a margin of surrounding skin. It is sutured.
The margin removed is defined as the area of normal-appearing tissue surrounding the lesion to be removed and has two components. The peripheral margin is the area of normal skin extending radially from the clinically suspicious lesion while the deep margin is the depth to which skin and subcutaneous tissue is entered and removed during the biopsy.
Equipment
The equipment needed for biopsies need not be elaborate but should be of good quality. The equipment should be properly maintained and sterilized prior to each use.
Following is a list of commonly used equipment ( Figs 40.1 and 40.2 ):
- ▪
Scalpel – #15 blade is the most often used
- ▪
Needle holder – Webster or Halsey
- ▪
Forceps – Adson type with teeth
- ▪
Scissors – Iris and Metzenbaum
- ▪
Skin hook – single or double prong
- ▪
Dermablade or Gillette blue blade
- ▪
Punch – 2, 3, 4, 5, 6, 8 mm
- ▪
Suture material
- ▪
Aluminum chloride – 35%
- ▪
Electrocautery
- ▪
Gauze
- ▪
Cotton-tipped applicator.
When performing a biopsy, a tray should be prepared with all the equipment that is needed for that particular procedure. On or near the tray should be the formalin-containing specimen bottle(s) with the patient's identifying information ( Fig. 40.3 ). This cannot be overemphasized, as there have been unfortunate cases of mislabeled specimen bottles and/or lost specimens that were left on the tray intended for subsequent transfer. Sterile surgical gloves are generally not necessary for biopsies, with the exception of excisional and incisional biopsies needing buried absorbable sutures to close the biopsied site.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here