A pulmonary granular cell tumour with associated hypertrophic osteopathy in a horse (abstract)

Authors: Sutton RH, Coleman GT
Publication: New Zealand Veterinary Journal, Volume 43, Issue 3, pp 123, Jun 1995
Publisher: Taylor and Francis

Animal type: Horse, Livestock
Subject Terms: Skeletal/bone/cartilage, Diagnostic procedures, Joint/arthrology, Locomotor, Neoplasia, Oncology, Disease/defect, Pathology, Respiratory system
Article class: Abstract

---

Abstract: A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.
Post-mortem findings included a 45 cm x 35 cm ovoid, pale, firm textured, multilobulated mass almost completely replacing the right lung. There were some pockets of dark mucinous material and some necrosis in the mass. The right lung weighed 14.7 kg as compared to the unaffected left lung weight of 1.9 kg. The principle histological feature was that of a diffuse population of large cells with a granular cytoplasm and small nuclei. Some of the granules showed mild PAS positivity. Ultrastructural studies showed these granules to be electron dense lysosomal bodies. The findings were characteristic of a granular cell tumour, which is a benign slow-developing neoplasm. The long bones showed patchy but marked periosteal bone proliferation.
Of 14 published cases of granular cell tumour in the horse, nine were in the right lung, three in the left lung, one involved both lungs and in one case the lung location was not specified. Only one case had an associated hypertrophic osteopathy. The derivation of the neoplasm is uncertain. Recent studies have suggested neuroectoderm origin from Schwann cells or Schwann cell precursors, but myogenic, epithelial and pluripotential mesenchymal cells have all been proposed.

---