Pulmonary histiocytic sarcoma in an Indian crested porcupine ( <i>Hystrix indica</i> ) with suspected dissemination

Abstract An 11‐year‐old female Indian crested porcupine ( Hystrix indica ) presented with cough in December 2022. Initial diagnostic testing revealed neutrophilia, and radiographs revealed a bronchial pattern as well as significant enlargement of the left main bronchus. Multiple antibiotic and anti‐inflammatory treatment regimens were attempted, but no response to therapy was seen. The patient developed lethargy and inappetence. Repeat radiographs were taken 6 weeks later and pulmonary soft tissue nodules were now noted. Neoplasia was suspected and the patient was euthanased due to lack of response to therapy and worsening quality of life. Gross postmortem examination revealed severe nodular growths in the lung, liver and spleen, which were found to be an inflamed round cell neoplasm on histopathology. The immunohistochemical staining of the cytoplasms of the neoplastic cells was strongly positive for CD204 antibody, suggesting a diagnosis of histiocytic sarcoma with suspected dissemination. This is the first report of this type of neoplasia in a porcupine.