Aim: Aim of this case report is to highlight the difficulties we faced in differentiating renal mass from the adrenal mass.
Background: MIBG positive uptake usually signify a neuroendocrine tumor. However, there is reported false positive MIBG uptake in the chromophobe variant of renal cell carcinoma (RCC).
Case description: A postmenopausal lady in her early 70s presented to our outpatient clinic with right-sided flank pain radiating to the back. On examination, a right hypochondriac region lump of size 10 × 8 cm was found. Contrast-enhanced computed tomography (CECT) scan done elsewhere showed a large, well-defined, smooth, lobulated, heterogeneously enhancing soft tissue lesion involving the upper pole of the right kidney measuring 15.5 × 11.4 × 11.2 cm, suspected to be an adrenal mass. The hormonal evaluation was inconclusive and the iodine-123-meta-iodobenzylguanidine (MIBG) scan showed concentration in the right suprarenal region. In view of the inconclusiveness of the findings, a repeat dedicated adrenal protocol CECT scan was done, which showed a mass arising from the superior pole of the kidney. The patient underwent open radical nephrectomy and final histopathology showed a chromophobe variant of RCC, which had shown a false positive uptake in the MIBG scan.
Conclusion: We must interpret radiological, clinical and pathological aspects of large suprarenal mass during evaluation and be aware of false positive uptakes in MIBG scan.
Clinical significance: An MIBG scan is a good tool for assessing the functionality of the neuroendocrine lesion, but we should always keep in mind the other conditions that can take up MIBG.
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