Biopsy Indications The indications for biopsy vary depending on the nature of the lesion in question. As a general rule, there are three categories of indications for biopsy: 1) atypically appearing lesions, 2) typically appearing lesions which behave in an atypical fashion, 3) progressive, longstanding lesions or conditions which cannot be adequately explained. For inflammatory conditions / dermatitis, the indications are predominantly related to the patient’s perception of the condition. Indications include, but are not limited to: 1) significant patient frustration, 2) severe symptomatology, 3) recalcitrance and 4) those cases that have entirely nonspecific clinical findings. In contrast, the indications for biopsy in relation to pigmented lesions of the skin are almost entirely related to the clinician’s impression of the lesion in question. Asymmetry of pigment, asymmetry of configuration, irregular outlines, and a diameter of greater than 6mm all represent indications for biopsy.off” the skin surface.
Pigmented lesions include all those lesions that might fall within the differential diagnosis of a pigmented malignant melanoma. This differential diagnosis includes lesions as disparate as solar lentigos, melanocytic nevi, seborrheic keratoses, tinea nigra, and talon noir. The criteria which should lead to the consideration of biopsy within this class of lesions are: 1) asymmetry of configuration, 2) asymmetry or variegation of color, 3) irregular outlines, or 4) size greater than 6mm in diameter . The symmetry of configuration should be assessed in 3 dimensions. As such, if the lesion is bisected in a plane that is perpendicular to the skin, each half should be identical, not just with regard t o i t s s h a p e along the skin’s surface, but also its elevations and depressions. It should also be stated that newly arising or changing lesions greater than 6mm in diameter in adults represent an absolute indication for biopsy, not a relative one. The indications for biopsy in relation to non-pigmented tumors of the skin are less well defined and lend themselves to more subjectivity than those for pigmented lesions. For the most part , papules, nodules, and plaques that cannot be effectively explained should receive prompt biopsy, or at minimum, clinical follow-up. Lesions that do not show evidence of resolution or involution should be sampled. An important point here is that simply harboring a papule or nodule that cannot be explained is of itself “atypical”.
Frank evidence of malignancy is not ne c e s s a ry to prompt a biopsy. In keeping with this theme, biopsies should be considered on all ulcers that cannot be adequately explained, and those that persist despite appropriately targeted therapy. Additional miscellaneous biopsy indications include: verrucous lesions in persons over 40 years of age, tumors of all types that show recalcitrance, and pyogenic granulomata in persons over 40 (Figure 7).