Computed tomographic and ultrasonographic diagnosis with successful excision of a lipoma in a shusui koi (Cyprinus carpio)

CASE DESCRIPTION A client-owned 12-year-old 10.3-kg (22.7-1b) female shusui koi (Cyprinus carpio) was evaluated because of an ulcerated mass on the left body wall, hyporexia, and decreased activity. CLINICAL FINDINGS The patient was anesthetized with a solution of eugenol in water for all examinations and procedures. An approximately 7 X 5 -cm smooth, raised, ulcerated, and firm mass was present ventral and lateral to the dorsal fin on the left body wall. Whole-body CT images obtained before and after contrast administration revealed an encapsulated, homogeneous, fat-opaque mass within the muscle. The mass was fat echoic with poor vascularity on ultrasonographic examination. Histologic evaluation of an ultrasound guided needle biopsy specimen was suggestive of a lipoma. TREATMENT AND OUTCOME The mass was excised, and the fish was placed in water with 0.3% salinity for 3 weeks after surgery. Postoperative antimicrobial administration was not indicated, and additional postoperative analgesic administration was considered impractical. The patient had noticeable improvement in appetite and activity with no indication of discomfort immediately following surgery. Five weeks after surgery, the incision site had healed with minimal scarring, and evaluation of CT images revealed no evidence of mass regrowth or regional osteomyelitis. CLINICAL RELEVANCE Antemortem evaluation and diagnosis of a lipoma in a teleost with subsequent excision was described. This report highlighted the logistic challenges associated with anesthesia, advanced diagnostic imaging, and surgery in fish and showed that they can be successfully overcome so that high-level medical care can be provided to such patients.