Unilateral Adrenal Tumor with Caudal Vena Cava Invasion in a Mixed Terrier Dog: A Case Report

Background: Adrenal tumors in dogs are uncommon but clinically significant neoplasms, often presenting with local invasion and potential systemic complications. Among these, unilateral adrenal masses with vascular extension represent a critical diagnostic challenge. Ultrasonography is the primary imaging modality for their initial detection and characterization. Case presentation: A ۹-year-old neutered male mixed Terrier was referred to Paytakht Veterinary Hospital for abdominal ultrasonography due to anorexia, diarrhea, abdominal distension, and lethargy. The owner declined further laboratory diagnostics, endocrine testing, advanced imaging, and therapeutic intervention; thus, only imaging studies were performed. A thoracic radiograph revealed no pulmonary nodules or metastases. Abdominal ultrasonography with microconvex and linear probes at ۱۰ MHz revealed the right adrenal mass measuring ۱۸.۵ × ۱۲.۷ mm. The lesion invaded the caudal vena cava (CVC), resulting in thrombus formation. The urinary bladder and prostate were normal. Diagnostic tests: In the absence of hormonal tests and histopathology, it is difficult to determine the exact nature of the adrenal mass, with differential diagnoses including adrenocortical carcinoma and pheochromocytoma. However, the ultrasonographic findings of a unilateral adrenal mass combined with vascular invasion/thrombosis constitute a critical finding strongly suggesting malignant adrenal neoplasia, most consistent with adrenocortical carcinoma or pheochromocytoma, and consistent with previous studies' findings. Furthermore, in several case series, tumor size has been considered an additional indicator of malignancy, with adrenal masses greater than ۲ cm in diameter being more likely malignant. Although the present case involved a lesion under this threshold, the vascular invasion was a decisive indicator of aggressive behavior. Adrenal tumors invading the CVC are associated with poor prognosis, high metastatic risk, and limited therapeutic options, particularly regarding surgical management. Despite the lack of confirmatory diagnostics, this case demonstrates that careful ultrasonographic evaluation alone can yield critical information for clinical decision-making. conclusion: This report emphasizes that in older dogs presenting with unilateral adrenal enlargement and evidence of vascular thrombus or invasion, clinicians should strongly suspect malignant adrenal disease—even without endocrine testing or histopathologic confirmation. Ultrasonography remains a valuable and accessible tool for identifying such high-risk lesions, aligning with findings from previous veterinary case reports.

کلیدواژه ها:

Adrenocortical carcinoma ، Adrenal gland neoplasia ، Caudal vena cava thrombosis ، ultrasonography