TITLE:
Kidney Curveball: A Rare Case of a Gastrointestinal Stromal Tumor with Renal Metastasis
AUTHORS:
Ian Daniel Francis, Chew Tien Chuen, Jaspreet Singh Cheema, Shankaran Thevarajah, Prama Veerappan, Dahziela Yunus, Khairunnisa Zuhaidi, Mohamed Arif Bin Hameed Sultan
KEYWORDS:
Gastrointestinal Tumour (GIST), Renal Metastasis, Surgical Oncology, Targeted Therapy, Tumour Recurrence
JOURNAL NAME:
Open Access Library Journal,
Vol.12 No.12,
December
24,
2025
ABSTRACT: Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract, accounting for approximately 1% of primary malignant gastrointestinal tumours. They arise from the interstitial cells of Cajal and are most frequently associated with KIT and PDGFRA mutations. GISTs primarily metastasize to the liver and peritoneum via hematogenous spread. Renal metastasis, however, is exceptionally rare, with only isolated cases reported in the literature. We report the case of a 55-year-old woman with a history of gastric GIST initially diagnosed in 2008, treated with laparoscopic wedge resection. She remained disease-free for 12 years before developing a local recurrence in 2020, for which repeat laparoscopic resection was performed. Histopathology demonstrated spindle and epithelioid tumour cells with a mitotic count of 13 - 15 per 50 high-power fields and positive immunohistochemical staining for CD117 and CD34, consistent with intermediate-risk GIST based on AFIP classification. Adjuvant imatinib was not initiated following either resection. Serial surveillance imaging remained unremarkable until mid-2023, when she presented with a right-sided abdominal mass and constitutional symptoms. Contrast-enhanced computed tomography revealed a large heterogeneously enhancing solid-cystic mass arising from the right kidney with high nephrometry complexity. Percutaneous renal biopsy demonstrated spindle and epithelioid tumour cells positive for CD117, CD34, and DOG1, confirming metastatic renal GIST. The patient was subsequently commenced on systemic tyrosine kinase inhibitor therapy with imatinib and remains under close oncological surveillance. This case highlights an extremely rare site of metastatic spread in GIST, posing significant diagnostic challenges as it may mimic a primary renal malignancy on imaging. Renal involvement likely reflects aggressive tumour biology and emphasizes the importance of long-term surveillance. In patients with a history of GIST, any new renal mass should prompt consideration of metastatic disease and early histological confirmation to guide appropriate systemic therapy.