Small Animal Dermatology, 3rd edition

38 BASICS

 A 6 mm biopsy punch is the preferred size to obtain skin tissue samples.

 When using a punch biopsy, tense the skin around the lesion to be biopsied

and position the punch perpendicular to the skin and rotate smoothly in one

direction only; do not twist back and forth to avoid artifactual damage of tissue

(Figure 4.1).

 Biopsy punches are single-use: blades easily become dulled, causing the tissue to tear

during the procedure.

 When using lidocaine, place the anesthesia in the subcutaneous compartment below

the tissue to be sampled; do not inject intradermally.

 Use a small-gauge needle to manipulate the tissue, or grasp the tissue sample below

the epidermis with a forceps to avoid crush artifacts.

 Separate the biopsy sample from underlying tissue by curved scissors placed beneath

the lifted sample (Figure 4.2).

 Gently blot blood off the biopsy sample.

 Place the sample immediately in the formalin.

 Small or thin specimens may be placed on a small piece of a tongue depressor with

the haired portion to the outside to prevent curling and then floated upside down in

the formalin.

 Avoid freezing.

PATHOLOGY REPORT (TABLES 4.1, 4.2, BOX 4.1)

 All skin biopsy samples must be accompanied by a complete biopsy request.

 Some laboratories permit submission of clinical images with tissues or a copy of the

written records (such as a summary or referral letter).

 Histopathology requests should include a thorough history (including drugs admin-

istered and responses), accurate and complete lesion description, clinical symptoms,

and differential diagnoses.

TABLE 4.1. Dermatohistopathology Report

Report item Remarks

Description Summarizes the histologic changes noted in the tissue

History Provides the pathologist’s summary of the case as presented by the clinician

(errors should be corrected with the pathologist if noted)

Morphologic diagnosis Reports the overall histologic pattern recognized

Etiologic diagnosis Identifies a causative disease or agent if recognized (e.g., bacteria, parasites,

fungal, etc.)

Comments The pathologist draws a correlation between the clinical features of the case

(provided by the clinician) and the histopathologic features of the biopsy. The

information provided by the clinician is vital for a valid conclusion to be given