A lesion is suspicious if you have to look at it twice because you are unsure whether it is benign or malignant (you experience a "moment of doubt" or a "double take").
A biopsy of a suspicious lesion should be strongly considered when it is:
- symptomatic (itching, burning, scaling, crusting, or bleeding)
- changing in color, shape, or size
You should also consider a biopsy if:
- the patient or family is concerned (more often than not the patient is right!)
- there is a personal and/or family history of skin cancer
- the growth is in an area treated previously and there is a question of recurrence
If the majority of your skin biopsies are confirmed as malignant, then you are recognizing the more advanced cancers that are clinically apparent. However, you may be missing less obvious cancers that are at an earlier stage. Unfortunately, as a rule, many "borderline" benign growths must be biopsied to diagnose cancer early enough. The more skin biopsies you do, the more accurate you become as a diagnostician.
The three most common techniques for skin biopsy are shave, incisional, and excisional biopsy. Clinical circumstances should dictate which method is most appropriate for each suspicious lesion. A shave biopsy samples the superficial portion of the lesion (epidermis and upper dermis) but not the deeper levels (lower dermis and subcutaneous tissue). An incisional biopsy samples both the superficial and deep levels but does not include the entire lesion. The gold standard for the diagnosis of a skin malignancy is the histopathological evaluation of an excisional biopsy specimen (i.e. an excision of skin which includes the entire lesion, a margin of clinically uninvolved skin around the lesion, and subcutaneous tissue beneath the lesion).
Understandably, it is impractical to completely excise every suspicious skin lesion; therefore shave and incisional biopsies are most commonly used. In any case, the biopsy should be adequate in depth and width for the pathologist to view a representative portion of the lesion. 10% formalin, ideally with a zinc buffer, is the medium of choice for the submission of skin samples for diagnosis of potential malignancy.