When to Biopsy
If the following lesion types are seen, consider submitting skin biopsies to diagnose the disease:
- Nodular lesions indicate an infectious, neoplastic, or immune-mediated cause.
- Eroded to ulcerative lesions are suggestive of an auto-immune disease or a drug reaction.
- Severely crusted lesions are suggestive of pemphigus foliaceus or cutaneous lymphoma.
- Large pustules with acantholytic cells on cytology are suggestive of pemphigus foliaceus.
How to Biopsy
Skin biopsies require only a few tools: 6-8mm biopsy punches, scissors, forceps, suture, lidocaine, and formalin.
Skin biopsies can be performed with local anesthesia alone or with additional mild sedation. Biopsies of the nasal planum or footpads require brief heavy sedation (such as a propofol) or general anesthesia because adequate local blocks are difficult to achieve.
Take biopsy samples from at least three lesions that vary in appearance because often only one sample will be diagnostic.
For ulcerative lesions, biopsy directly adjacent to the ulcer. Do not biopsy the ulcer itself because the lack of epidermis often prevents a diagnosis.
Biopsy Submission Recommendations
For nodular dermatitis, consider submitting a biopsy for tissue cultures in addition to histopathology. Sometimes organisms are not seen in the tissue but are cultured. We recommend submitting tissue for aerobic, anaerobic, mycobacterial, and fungal cultures.
Consider submitting your tissue to the UT Pathology Service or a dermatohistopathologist in order to obtain the most information from your biopsy. Photos of the clinical lesions can be helpful to the pathologist.
DVM Pathology Associates
Dr. Diana Loeffler
Dr. Joanne Mansell
Texas A&M College of Vet Med
Prairie Diagnostic Services
Dr. Ted Clark
University of Saskatoon
52 Campus Drive