Concurrent extra‐adrenal paraganglioma and uterine leiomyosarcoma in a degu (Octodon degus)

Abstract

An adult, female degu (Octodon degus) presented with a single, firm, nodular, 8 × 8 × 10 mm, fast‐growing mass located between the cranial thoracic vertebrae and the cranial aspect of the right scapula. Cytology, histopathology and immunohistochemistry confirmed an extra‐adrenal paraganglioma (chromogranin A, neuron‐specific enolase and S100 positive, and cytokeratin AE1/3 negative) within the deep adipose tissue underlying the panniculus muscle. Complete surgical excision was achieved; however, within 1 month after surgery, a novel fast‐growing intra‐abdominal mass was detected. The animal was subsequently euthanased. Postmortem examination only revealed a single, well‐demarcated, spherical, firm, 40 × 40 × 42 mm tumour arising from within the left uterine horn. Histology and immunohistochemistry confirmed a uterine leiomyosarcoma (smooth muscle actin positive). This case report represents the first case of an extra‐adrenal paraganglioma and the second case of a uterine‐specific leiomyosarcoma in this species.