T-cell lymphoma in the horse probably arising from the skin: A case report

Lymphoma is a malignant solid neoplasm of the lymphoid tissue of unknown etiology, affecting equine species, unrelated to the age, with a prevalence ranging from 1 to 3% of all tumoral forms. Four forms of lymphomas can be classified: generalized or multicentric, alimentary or intestinal, mediastinal or thoracic, and extranodal, The last type affects in prevalence skin, upper respiratory tract, eye and central nervous system. The most common type of lymphoma is the multicentric form. Some authors consider more common the cutaneous form, but for others it is rare. On the basis of histo-morphological features, lymphoma is distinguished as "high" or "low" malignancy degree. According to the prevalence of the lymphocyte type based on immunophenotyping is divided in B or T cell lymphoma. In this paper, a case of lymphoma in a trotter horse is reported, which presented at the beginning some cutaneous swelling and mild-moderate lymphoadenopathy. The diagnosis has been achieved by mean, of several exams including a complete blood count, an extended biochemical profile, coagulation tests, serum protein electrophoresis, rectal palpation, liver and spleen echography, fine needle aspiration and biopsy of both, the enlarged lymph nodes and cutaneous nodules. The horse has been recognized affected by a "T cell" lymphoma associated by significant histiocytic infiltration, probably having skin origin. Unfortunately, without the necroscopy report denied by the horse's owner, the multicentric or the mediastinal form has not been ruled out.