Multicentric lymphoma in a pony presented as a case of metastatic strangles

A four-year-old pony was presented for investigation of weight loss, pyrexia, multicentric lymph node enlargement and mucopurulent nasal discharge. The pony came from an area endemic for Streptococcus equi subspecies equi (strangles) hence metastatic strangles was suspected initially. Multiple enlarged non-painful lymph nodes were also highly suggestive of multicentric lymphoma. Nasal discharge was negative by culture and PCR for Streptococcus equi subspecies equi while fine needle aspirate of three lymph nodes revealed a homogenous population of small lymphocytes with normal morphology. Based on the poor prognosis the pony was euthanased. During histopathology neoplastic cells were detected in various lymph nodes and in the spleen, Immunohistochemistry gave the final diagnosis; low-grade diffuse small T cell multicentric lymphoma. Lymphoma has a broad range of presentations and is difficult to diagnose ante mortem but should be considered a differential diagnosis where generalised lymphadenopathy is detected, although this may be confounded by signs of upper airway infection.