The center of the tumor was mineralized extensively, as noted in radiographic analysis and computed tomography; thus, the tumor was sectioned after demineralization. was enlarged by an amorphous mass with opaque areas, indicative of mineralization. Upon histologic examination, the mass was comprised of malignant mesenchymal cells that produced mucinous matrix. The tumor cells were positive for vimentin and COX-2, but negative for pancytokeratin; the matrix stained positively with alcian blue. Therefore, the mass was diagnosed as a renal interstitial cell tumor, with malignant features. COX-2 may be useful in the diagnosis of canine renal interstitial cell tumors, similar to its diagnostic role in humans. strong class=”kwd-title” Keywords: dogs, image, immunohistochemistry, malignant, renal interstitial Rabbit Polyclonal to MLTK cell tumor In dogs, primary renal tumors are relatively uncommon, comprising 0.3C1.5% of all reported canine tumors.1,2,11 Nearly 70% of canine renal tumors are derived from epithelial cells, 25% Cathepsin Inhibitor 1 are derived Cathepsin Inhibitor 1 from mesenchymal cells, and 5% are nephroblastomas.10 Notably, renal interstitial cell tumors have been reported only rarely.10 Renal interstitial cell tumors are believed to arise from renal interstitial cells that contain prostaglandin and arachidonic acid.10 Renal interstitial cells exhibit distinctive ultrastructural features such as lipid-rich cytoplasmic vesicles; this neutral antihypertensive lipid can lower arterial blood pressure.5,10 Most renomedullary interstitial cells express high levels of cyclooxygenase-2 Cathepsin Inhibitor 1 (COX-2), which is the inducible isoform of prostaglandin-endoperoxide Cathepsin Inhibitor 1 synthase 2.5,13 In humans, renal interstitial cell tumors are known to be COX-2 positive.10 Moreover, in humans, these mesenchymal tumors are known as renomedullary interstitial cell tumors, which are benign neoplasms diagnosed only rarely prior to death; they were previously described as medullary fibromas or hamartomas.12,13 The tumors are commonly identified at autopsy, in up to 50% of autopsy cases; most are asymptomatic and 5?mm diameter, hence the antemortem diagnostic rate is low. 12 In previously reported cases of canine renal interstitial cell tumors, only benign features were observed as in humans; moreover, there were no data regarding clinicopathologic or imaging findings (e.g., radiography, ultrasonography, or computed tomography).4 We describe herein a renal interstitial cell tumor with malignant features in a dog. A 17-y-old spayed female Maltese dog weighing 3.9?kg was presented because of anorexia and an enlarged right side of her abdomen. Blood was collected for a complete blood count and chemistry panel. Creatinine and urea concentrations were increased as were the activities of amylase and lipase; moderate anemia and leukocytosis were present (Table 1). Table 1. Clinicopathologic Cathepsin Inhibitor 1 findings prior to surgery in a dog with a renal interstitial cell tumor. thead th align=”center” rowspan=”1″ colspan=”1″ Parameter /th th align=”center” rowspan=”1″ colspan=”1″ Unit /th th align=”center” rowspan=”1″ colspan=”1″ Result /th th align=”center” rowspan=”1″ colspan=”1″ Reference interval6 /th /thead CBC?Leukocytes109/L274.0C15.5?RBC1012/L3.74.8C9.3?Hemoglobing/L95122C203?HematocritL/L0.250.36C0.6Chemistry?Albuming/L1227C44?Creatininemol/L19444.2C141.4?Ureammol/L15.52.1C8.9?AmylaseU/L5,480219C1,125?LipaseU/L1,02677C695 Open in a separate window CBC = complete blood count; RBC = red blood cells. Radiographic findings included an ovoid mass with soft tissue opacity in the right side of the abdominal cavity, as well as deviation of the pylorus and intestines in the opposite direction. A large amorphous structure with mineralization opacity was identified in the right cranioCmid-abdominal cavity (2.5?cm3) and was located in the mass. The right kidney was enlarged on ultrasonographic examination, and normal architecture was lost. A heterogeneously hyperechoic lesion was identified in the right renal mass, caudal to the anechoic lesion. Computed tomography revealed an irregularly enlarged caudal pole of the right kidney (71 81 54?mm; Fig. 1). A 2.5-cm3 stellate-shaped area of mineralization was identified in the right renal pelvis and diverticulum; the mass displaced other abdominal organs to the left. No other abnormalities or metastases of the tumor were found in other organs by imaging. The mass was removed surgically under general anesthesia. The excised mass was fixed in 10% neutral-buffered formalin, and was sent to the Department of Veterinary Pathology, College of Veterinary Medicine, Konkuk University, Republic of Korea. The dog died one week after surgery, and an autopsy was not performed at the referral hospital. Open in a separate window Figure 1. Computed tomography of renal interstitial cell tumor in a dog. The preoperative image showed an irregularly enlarged mass. The cranial region of the right kidney maintained a normal shape, but its position was changed in the cranial direction by the mass. The mineralized region (arrow) was found between normal kidney and the mass. On gross examination, the proper kidney included one irregular, huge, red-to-ivory mass (70 78 55?mm) over the elongated caudal pole; the cranial pole was of regular form (Fig. 2). The guts from the tumor thoroughly was mineralized, as observed in radiographic evaluation and computed tomography; hence, the tumor was sectioned after demineralization. Cross-section from the cranial pole of the proper kidney uncovered tissue similar compared to that of regular kidney macroscopically. Open up in another window Amount 2. Renal interstitial cell tumor within a pup. The mass changed ~30% of the proper kidney; recognizable kidney tissues remained. Club = 1?cm. The mass consistently was prepared, and.