A REVIEW OF NEOPLASIA IN PROSIMIANS IN HUMAN CARE FROM 1995 TO 2022.

This retrospective study of neoplasia in prosimians in human care reports histologically diagnosed cases from the archives of a nondomestic species pathology service between 1995 and 2022, primarily submitted from zoological institutions. To date, the only prior retrospective study of neoplasia in prosimians, published in 2009, was conducted with cases from a single institution specializing in prosimian noninvasive research and care. In the present study, a total of 153 neoplasms from 109 individuals were identified in the pathology service archives. The most commonly affected species belonged to the Lemuridae (92/109, 84.4%), particularly ring-tailed lemurs (Lemur catta; 55/109, 50.5%), black-and-white ruffed lemurs (Varecia variegata; 19/109, 17.4%), and red ruffed lemurs (Varecia rubra; 14/109, 12.8%). The digestive (49/153, 32.0%), reproductive (35/153, 22.9%), and integumentary (30/153, 19.6%) systems were most commonly affected. Hepatocellular neoplasia was the most common neoplasm overall (35/153, 22.9%), with a large proportion of hepatocellular carcinoma (23/35, 65.7%), suggesting a possible predisposition to this tumor in prosimians. The findings support aggressive behavior of these tumors in prosimians, and a majority (13/23, 56.5%) of cases had evidence of metastasis at the time of submission. Mammary neoplasia was also common (25/153, 16.3%) and predominantly malignant (18/25, 72.0%), in contrast with previous literature, although metastasis was uncommonly reported. The most common integumentary neoplasms were papillomas (12/30, 40.0%), and one report identified squamous cell carcinoma arising directly from a squamous papilloma. Several tumor types are reported herein for the first time in prosimian species, to the authors' knowledge. A literature review identifying additional cases reported since 2009 is also reported. This study contributes a large number of prosimian neoplasia cases to the existing literature to help determine trends in zoological collections and to inform captive prosimian health management.