Diffuse large B-cell lymphoma of the trachea was diagnosed in a 14-year-old domestic shorthaired cat suffering from dyspnoea. X-ray examination revealed marked stenosis of the lumen in the thoracic segment of the trachea. Post-mortem examination of the trachea disclosed two formations. The larger, visible in the radiograph, was formed by thickened tracheal wall. The smaller one was of crest appearance and was located in the cranial segment of the trachea, immediately behind the larynx. The tumour was characterised by immunohistochemical positivity to CD79αcy epitope in the neoplastic cells.

The objective of this contribution was to present a case report of gastrointestinal stromal tumour (GIST) in one guinea pig: a pet animal, male, 3.5 year of age, tricolour. Approximately for five weeks before death wasting, in spite of good appetite, decreased locomotor activity, soft and malodorous faeces were observed by the owner. The animal spontaneously died and at necropsy a grey-pink coloured tumour of walnut size located in the terminal segment of the ileum was observed. A solid malignant tumour of mesenchymal appearance was diagnosed histologically. One part of the sample consisted of tightly packed spindle cells arranged in interlacing fascicles, in the other part epithelioid cells predominated with slightly myxoid intercellular matrix. Lymphocytic sheaths were observed around some blood capillaries. Immunohistochemistry revealed positivity for actin, CD 117, neuron-specific enolase, glial fibrillary acidic protein, and p53 protein; however, desmin, S100 protein and synaptophysin were negative. On the basis of histological and immunohistochemical examinations GIST was diagnosed. Intestine, neoplasia, interstitial cells of Cajal, GISTRamon y Cajal described special cells located in the vicinity of the neuronal plexuses at first in 1889 and later in 1893 and 1911(Kobayashi et al. 1989 Lee et al. 2007). A tumour arising from ICC is named the gastrointestinal stromal tumour (GIST), and is considered as a low-grade sarcoma harbouring mutation of c-kit. GIST was first described in humans in the 1980s, and the term GIST was first coined by Mazur and Clark in 1983 (Ozcan et al. 2007). Banerjee et al. (1991) have described GIST in two Rhesus macaques (Macaca mulatta), Del Piero et al. (2001) and Hafner et al. (2001) diagnosed it in horses, andFrost et al. (2003) characterized and analyzed 29 cases of GIST in dogs. To the best of our knowledge, the histogenesis of a tumour of ICC has not been described in a guinea pig until now. For this reason we publish our observation. Case description The animalGuinea pig, male, 3.5 year of age, tricolour, was kept as a pet animal in a household. Approximately for five weeks before death wasting, in spite of good appetite, decreased locomotor activity, soft and malodorous faeces were observed by the owner. Veterinary clinician revealed by palpation a globoid formation of walnut size in the abdominal cavity. Some days later the animal died spontaneously.