here - Australian College of Veterinary Scientists

composed of collagen with only small numbers of fibroblasts/fibrocytes of normal
morphology and only rarely are mitotic figures visible. Histological differentiation of
sarcoids and fibrosarcomas may be more problematical; however, anaplasia of
fibroblasts is rarely observed in sarcoids and perpendicular alignment of fibroblasts
beneath the epidermis is not expected in fibrosarcomas or other mesenchymal
neoplasms. Histological detection of close association of a spindle cell tumour with
a peripheral nerve or its sheath may be useful in identifying peripheral nerve sheath
tumours.
Alternative diagnostic methods
With the advent of polymerase chain reaction (PCR) technology, there is the
potential for rapid diagnosis of equine sarcoids by identification of bovine
papillomaviral DNA in swabs or scrapings of the surface of suspected lesions. In
one study of 92 sarcoids, the overall sensitivity of this test was 88% for swabs and
91% for scrapings, with all sarcoids having partially or completely ulcerated surfaces
being correctly identified. The swab technique was found to be unsuitable for occult
sarcoids due to low sensitivity.
PCR amplification of bovine papillomaviral sequences can also be performed on
formalin-fixed, paraffin-embedded tissues to confirm a diagnosis of equine sarcoid
when histopathological examination of biopsy material is inconclusive.
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ACVSC Proceedings Dermatology Chapter Science Week 2005