Pulmonary angiocentric lymphoma (lymphomatoid granulomatosis) in a donkey.

This study focuses on a previously unreported case of angiocentric lymphoma, similar to lymphomatoid granulomatosis, in a 36-year-old donkey. The research investigates the presence of equine gamma herpesvirus but does not find any evidence to relate it to the lymphoma.

Case Presentation

• The study revolves around a 36-year-old donkey that showed symptoms of respiratory distress (dyspnoea), fever (pyrexia), low albumin (hypoalbuminaemia) in blood, and abnormal accumulation of fluid in the cavities or tissues (oedema). Owing to continual clinical deterioration, the donkey had to be euthanized. A detailed examination of the donkey’s lungs revealed several nodules (small lumps), approximately 5-10mm in size, spread throughout the lungs.

Microscopical Examination

• The microscopic examination revealed that the lungs were occupied predominantly by an angiocentric and bronchocentric to diffuse mixed populace of various cells. These mainly consisted of small mature and atypical lymphocytes (white blood cells), histiocytes (immune system cells), plasma cells (white blood cells that secrete antibodies), and lesser numbers of eosinophils (white blood cells that fight infection).
• The infiltrate (accumulation of cells in tissues where they normally aren’t present) was composed of numerous small mature and fewer atypical CD3(+) T lymphocytes (a type of immune cell).
• Accompanying these T cells were low numbers of CD20(+) and CD79a(+) B cells, some of which demonstrated atypical behavior.

Diagnosis and Findings

• These infiltrates were consistent with a type of cancer known as an angiocentric lymphoma. In particular, their characteristics resembled those seen with lymphomatoid granulomatosis, a rare and aggressive lymphoproliferative disorder associated with Epstein-Barr virus (EBV) in humans.
• However, when subjected to immunohistochemistry for EBV latent membrane protein and polymerase chain reaction analysis for equine gamma herpesvirus DNA, the results were negative, eliminating the possibility of any underlying gamma herpesvirus infection.
• This was the first case of angiocentric lymphoma reported in a donkey and the first case of a lymphomatoid granulomatosis-like disease in an animal without evidence of concurrent infection with a gamma herpesvirus.