Endocrine Abstracts

JOINT2552

Introduction: Liposarcomas are rare malignant tumors arising from adipose tissue, with the kidney being an exceptional site of origin. Due to their large size and mass effect, renal liposarcomas can mimic adrenal tumors, leading to diagnostic confusion, especially when the adrenal gland is not clearly visualized. This case highlights the challenges of adrenal imaging and the importance of histopathological confirmation in ambiguous cases.

Observation: A 64-year-old male, with no prior medical history, was referred for the evaluation of a 17 cm adrenal mass, incidentally discovered on an abdominal CT scan performed due to unexplained weight loss (17% in one month) and pelvic pain. MRI revealed a large, solid-cystic right renal mass (18.6 × 14.8 cm in axial diameter, 21.5 cm in height), with heterogeneous peripheral enhancement, multiple cystic areas, and intermediate T2 signal intensity. The mass displaced the right kidney downward, while the right adrenal gland was not visualized, raising strong suspicion of an adrenal origin. There was no vascular invasion, but the mass displaced the inferior vena cava and right renal vein. A mild right pleural effusion was also noted. Upon referral to endocrinology, the patient exhibited no signs of hypercortisolism or hypercatabolism. He had abdominal asymmetry, normal skin examination, and erectile dysfunction without gynecomastia or loss of libido. Biochemical exams showed normal plasma metanephrines, and a 1 mg dexamethasone suppression test ruled out hypercortisolism. Based on imaging and clinical findings, an adrenocortical carcinoma was strongly suspected, leading to surgical resection. However, histopathology unexpectedly revealed a high-grade dedifferentiated renal liposarcoma (FNCLCC grade 3), measuring 22 cm, with perirenal fat invasion but no vascular emboli, perineural invasion, or involvement of the renal hilum, ureter, or right adrenal gland.

Discussion and Conclusion: This case highlights the diagnostic challenges of large renal tumors and the potential pitfalls of adrenal imaging. Despite radiological findings highly suggestive of an adrenal malignancy, the true origin of the mass was renal, demonstrating how large renal tumors can compress or displace the adrenal gland, creating a misleading appearance. The absence of hormonal abnormalities, the lack of vascular invasion, and the atypical imaging characteristics should raise suspicion of non-adrenal neoplasms in similar cases. This case reinforces the importance of a multidisciplinary approach, careful interpretation of imaging findings, and the necessity of histopathological confirmation to avoid misdiagnosis.