Myelolipomas are rare mesenchymal tumors composed of adipose and hematopoietic tissue.3 They have been reported in many species, including domestic dogs and cats, cattle, birds, wild felids, and non-human primates.1-8 Myelolipomas in Callitrichidae have been reported at necropsy and rarely antemortem.2-8 Multiple cases of hepatic myelolipomas in a captive collection of Goeldi’s monkeys (Callimico goeldii) prompted a retrospective study to determine the prevalence and investigate factors associated with this condition. A total of 816 necropsy reports (1965–2013) collected from multiple captive collections were reviewed. Myelolipomas were present in 16.8% (n=137) of pathology reports, with a nonsignificant (p=0.095) trend toward female cases (54.7% of diagnosed cases). There was a significantly older mean age at death in affected animals (131.78 months) compared to unaffected animals (80.32 months) (p<0.001). Correlation of inbreeding (p=0.252) and generations removed from the wild (p=0.994) did not differ compared to non-affected animals. All myelolipomas were diagnosed either focally (n=68, 49.6%) or multifocally (n=69, 50.4%) in the liver, and less commonly in the adrenal glands, spleen, or mediastinum. The continent of diagnosis was not evenly distributed (p<0.0001), with the majority of cases occurring in North America. Future studies are merited to examine the prevalence in living collections. Utilization of modern imaging modalities for accurate age of diagnosis, staging, and monitoring progression of the disease is warranted. Examining family genealogies, links to other disease processes, as well as examination of clinical and husbandry trends in affected animals may help to determine predisposing factors of myelolipoma in this species.
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