An eight-year-old, spayed female Golden Retriever weighing 32 kg was presented to the University of Tennessee Veterinary Medical Center (UT-VMC) for evaluation of an intra-abdominal mass and hypercalcemia. The dog was spayed 6 years previously and reportedly normal until 10 days prior to presentation, when the dog was evaluated by the referring veterinarian for lethargy. A large cystic mass measuring 10 cm x 7 cm x 3 cm was noted on the right flank, which was drained by the referring veterinarian. This mass had reportedly been present for approximately one year prior to presentation. The dog was treated empirically with cephalexin at 22 mg/kg PO q12h (AmerisourceBergen, Chesterbrook, PA, USA). The lethargy resolved, and the dog was clinically normal at the time of presentation to UT-VMC, aside from reportedly licking and biting at its right flank. Physical examination revealed persistence of the reported subcutaneous cystic mass on the right flank as well as a firm, nonpainful intra-abdominal mass caudal to the right kidney. Hematology was unremarkable. Biochemistry revealed mild total hypercalcemia (13.3mg/dL; reference range 10-12 mg/dL), normal phosphorus (2.8 mg/dL; reference range 2.5-5.9 mg/dL), mildly elevated creatinine (1.3 mg/dL; reference range 0.3-1.1 mg/dL), normal BUN (16 mg/dL; reference range 7-37 mg/dL), and mild hyperglobulinemia (4.1 g/dL; reference range 1.9-3.1 g/dL). Urinalysis revealed isosthenuria but was otherwise unremarkable. A hypercalcemia of malignancy profile was performed at the Michigan State University Veterinary Diagnostic Laboratory where these tests had previously been validated, revealing marked ionized hypercalcemia (1.75 mmol/L; reference range 1.26-1.39 mmol/L), a plasma PTH concentration below the reference range (0 pmol/L; reference range 0.5-5.8 pmol/L), and normal plasma PTHrP concentration (0 pmol/L; reference range 0.0-1.0 pmol/L). Serum concentration of 1,25[OH]2D was normal (97 nmol/L; reference range 60-125 nmol/L). Radiographic (Super 80CP, Philips Medical Systems, Bothell, WA) findings included two large right caudodorsal abdominal soft tissue opaque masses in close proximity to one another, with evidence of mild fluid streaking of the fat surrounding both structures (). The first mass was located within the subcutaneous tissues of the right caudodorsal abdominal wall and was associated with focal medial deviation of the abdominal wall. The second was within the right caudodorsal abdominal cavity, caudal to the right kidney. It could not be determined whether the abdominal mass was associated with the body wall mass or whether these represented two distinct processes. Differential diagnoses for the intraabdominal mass included a granuloma, hematoma, or neoplasia, possibly originating from the mesentery or a regional lymph node. Differential diagnoses for the abdominal wall mass included benign or malignant etiologies such as a granuloma, abscess, or a sarcoma. Abdominal ultrasound (Epiq 5, Philips Ultrasound, Bothell, WA, USA) was performed next to further characterize the identified masses. The sonographic examination was performed with the patient in dorsal recumbency using a microconvex 8 MHz transducer, a convex 9 MHz transducer, and a linear 12 MHz transducer. A heterogeneous, non-organ associated abdominal mass with strongly hyperechoic, shadowing foci within its center was identified in the right caudal abdomen (). This mass had multiple finger-like hyperechoic projections extending laterally and caudally, connecting it with the large extra-abdominal, cystic mass in the right lumbar region. The intra-abdominal mass was moderately vascularized when interrogated with color Doppler (), with evidence of multiple relatively large, slightly tortuous, branching intralesional blood vessels. Given the sonographic appearance of these lesions, differential diagnoses included malignant neoplasia, such as sarcoma or carcinoma, or a granulomatous inflammatory process (such as secondary to a chronic foreign body or fungal infection). Ultrasound-guided fine-needle aspiration of the abdominal mass was performed to obtain tissue samples for cytologic analysis, which was consistent with pyogranulomatous inflammation. CT (Brilliance, Philips Medical Systems, Cleveland, OH, USA) of the abdomen was performed using a 40-slice helical scanner for further characterization of the relationship between the intra-abdominal and extra-abdominal lesions, in preparation for surgical excision. A submillimeter dataset of the abdomen was acquired and images were reconstructed in 0.9mm, 1.5 mm, and 5 mm slice thickness utilizing bone and soft tissue algorithms. The acquisition was repeated following intravenous administration of Ioversol 350 mgI/ml, a nonionic iodinated contrast medium (Tyco Healthcare/Mallinckrodt, Milwaukee, WI, USA) at a dosage of 2.2 mg/kg IV. A well-defined, heterogeneously contrast-enhancing, thick-walled, cavitary, soft tissue attenuating, abdominal mass was present caudal to the right kidney (). This mass was confluent with the distal tip of the right limb of the pancreas () and intimately associated with a small intestinal segment. Despite its close association with the small intestine and pancreas, this mass was not centered on these structures and therefore was most consistent with a non-organ associated abdominal mass with secondary involvement of adjacent abdominal organs. A few pinpoint mineral attenuating foci were noted within this mass. A large, rim enhancing, cystic subcutaneous mass was also identified in the right lumbar subcutaneous tissues, resulting in focal medial displacement of the abdominal wall (). In addition, ill-defined, peripherally contrast-enhancing tracts were seen extending through the right hypaxial musculature from the level of the midbody of the L4 vertebra to the level of S3 (). Both masses and the peripherally contrast-enhancing tracts in the hypaxial musculature were all interconnected by thick, peripherally contrast-enhancing soft tissue attenuating stalks (). Given the confirmed connection of the two masses, extra-abdominal extension of an intra-abdominal mass with multiple fistulous tracts led to a primary differential diagnosis of a granulomatous inflammatory process, such as secondary to a chronic foreign body. An aggressive soft tissue neoplasm (i.e., soft tissue sarcoma) was also considered. An exploratory laparotomy was subsequently performed. The intra-abdominal portion of the mass was large (7.5 cm x 4.5 cm) and nonresectable because it was highly vascularized with extensive adhesions to the colon and omentum. The thick, fibrous capsule was incised to reveal fluid and a 4-inch x 4-inch gauze, most likely from the ovariohysterectomy 6 years earlier. A wedge biopsy of the mass was obtained for histopathological analysis and culture. The mass was lavaged, omentalized, and sutured closed. The abdomen was flushed with sterile saline and closed. A stab incision was made into the second subcutaneous cystic mass dorsolateral to the incision site. The content of this cystic mass was drained using suction. A Jackson-Pratt drain (Cardinal Health, Waukegan, Illinois, USA) was subsequently placed into this structure and secured in place for 24 hours. Approximately 240 mL of fluid was drained from the extra-abdominal portion of the mass. Histopathology of the biopsy sample from the intraabdominal mass revealed chronic, fibrosing, pyogranulomatous and lymphoplasmacytic fasciitis with marked pancreatic atrophy and loss. This was consistent with a gossypiboma which had incorporated and replaced portions of the pancreas, likely the most distal aspect of the right pancreatic limb which was intimately associated with the mass on presurgical imaging. Aerobic and anaerobic culture of a portion of the biopsy sample revealed Streptococcus agalactiae from broth only, and 2 colonies of Staphylococcus sp. No growth was seen on fungal culture after 5 weeks. Postoperatively, the dog was treated supportively with intravenous fluid therapy, a fentanyl/lidocaine constant rate infusion (AmerisourceBergen, Chesterbrook, PA, USA) at a dosage varying between 2 and 5 mcg/kg/hr, ampicillin (AmerisourceBergen, Chesterbrook, PA, USA) (705 mg, IV, q 8 h), and zoledronate (Novartis Pharmaceuticals Corp, East Hanover, NJ) at a total dosage of 4 mg IV given once. Ionized calcium normalized within 48 hours (1.34 mmol/L; reference range 1.26-1.39 mmol/L). The dog recovered uneventfully and was discharged 24 hours following surgery with tramadol (AmerisourceBergen, Chesterbrook, PA, USA ) at a dosage of 3 mg/kg PO q12h for 5 days, and amoxicillin (Zoetis, Parsippany, NJ, USA) at a dosage of 24 mg/kg PO q 12 h for 10 days. The dog was reevaluated approximately 3 months following surgery. Clinically the dog was normal and normocalcemic (ionized calcium 1.32 mmol/L; reference range 1.26-1.39 mmol/L). Abdominal CT was repeated prior to and following intravenous contrast medium administration using the same imaging parameters as the initial examination. The soft tissue attenuating mass within the right caudal abdomen had markedly decreased in size and was less contrast-enhancing, with persistence of a non-contrast-enhancing hypoattenuating center (), and few pinpoint, mineral attenuating foci within it. The thick stalk previously extending from the mass through the right abdominal wall was no longer identified, and the stalk connecting the abdominal mass to the hypaxial musculature was decreased in thickness and no longer contrast-enhancing. There was however persistence of a thin, non-contrast-enhancing, soft tissue attenuating stalk connecting the cranial aspect of this mass to the distal tip of the right limb of the pancreas. The large cystic mass in the right dorsolateral abdominal subcutaneous tissues had resolved, with only a small, ill-defined region of mildly contrast-enhancing thickening of the subcutaneous tissues remaining. The fistulous tracts extending through the right hypaxial musculature had resolved. These findings were consistent with resolving granulomatous inflammation following surgical debridement of a gossypiboma. The residual stalks interconnecting some of these structures and the ill-defined, mild thickening of the right midabdominal subcutaneous tissues were most consistent with residual fibrosis, although persistence or progression of previously resolved fistulous tracts could not be entirely excluded due to lack of additional follow-up imaging.