Skin disease and neoplasia

The following AHL LabNotes provide useful tips for practitioners when submitting skin biopsies and large cutaneous masses to the laboratory. A testing algorithm for suspected lymphoid neoplasia is also included

LabNote 41: Fixation and transport of large excisional biopsies 

LabNote 44: Testing algorithm for suspected lymphoid neoplasms – clonality, PARR 

LabNote 45:  Maximizing the benefit of surgical biopsies 

A.  History: Please provide the following information, as appropriate:

  • age, breed (there are breed predilections for many skin diseases), coat color, sex (skin disease may be sex-related)
  • other animals affected
  • duration of problem
  • lesion location and distribution (diagrams or photos are welcome)
  • therapy (especially dose and duration of corticosteroid therapy)

B.  Submitting samples

Histopathology

  • If you feel that the site of each biopsy is important (e.g., multiple tumors), please place each biopsy in a separate labeled container.
  • Biopsies may be "labeled" with suture material or ink - biopsies usually fall off cardboard or tongue depressors.

Skin disease

  • Biopsy early, rather than as a last resort!
  • Select biopsies from active primary lesions, and avoid older, secondary, healing or self-traumatized areas. Biopsy across the margins of larger lesions, rather than the central area. For pustular skin diseases, biopsy intact pustules, if available.
  • Long hair may be clipped, but do not shave, scrub, or prep the skin - crusts or other surface material may be diagnostically valuable.
  • Submit in formalin a minimum of 3, full-depth, punch biopsies or 1-cm elliptical excision biopsies; 6-mm biopsies are preferred - electrocautery or crushing with forceps distorts morphology.
  • Photographs are always welcomed and can be sent via email to specroom@uoguelph.ca
  • Useful interpretation is only possible in conjunction with a detailed clinical history.

Parasitology

  • Scrape the periphery of several lesions.
  • If possible, use glycerine on the lesion as a viscous vehicle to remove and hold material for sampling.
  • Scrape deeply enough to cause mild pinpoint hemorrhage; the sample in glycerine should be pink.
  • It is convenient to send the material and blade used, packaged in tinfoil or in a test tube.
  • Caution - do not use glycerine on samples destined for mycology.

Bacteriology

  • Submit a swab/biopsy taken from the lesion(s) in transport medium.
  • Biopsies are preferable, especially if anaerobic culture or mycology is requested.

Mycology

  • Submit skin scrapings and plucked hairs in a test tube.  Do not use oil or glycerine to collect samples.
  • If enough hair is received, a KOH wet mount will be examined for dermatophytes and interim results will be available.

Virology

  • PCR: ovine parapoxvirus (orf), bovine parapoxvirus (papular stomatitis).

      Molecular Biology

  • Bovine papillomavirus (equine sarcoid)

Neoplasia

  • AHL technical staff routinely ink margins of tumors unless the tumor has been submitted in fragments.  In order to better estimate the completeness of removal, large tumors may require additional slides to be cut and examined - these are done at extra charge.  Unless you indicate that you do not want margins examined, please expect additional costs for large (>2 cm) tumors.
  • IHC - the AHL has a wide array of immunohistochemical cell markers available. Please refer to Fee Schedule for tests.
  • Lymphoma immunophenotyping may be performed by flow cytometry on aspirated samples submitted in buffer, using a panel of antibodies. Enquire about details.
  • Lymphocyte clonality PCR is available to confirm lymphoma in selected circumstances.