Type:
Educational Exhibit
Keywords:
Abdomen, Kidney, CT, MR, Ultrasound, Biopsy, Cancer, Cysts
Authors:
A. Patel1, G. Chow2, R. Vaja3, C. King1, S. chang1; 1Stevenage/UK, 2London/UK, 3CB2 0SP/UK
DOI:
10.1594/ecr2018/C-2392
Background
Incidentally detected renal lesions are an increasingly common occurence in everyday practice for radiologists,
largely driven by the the rapidly increasing use of abdominal imaging in medical practice.1 Whilst the majority of these incidental lesions represent simple cysts,
a significant proportion of incidental lesions are too small to reliably characterise or are identified on examinations that are not designed to fully evaluate them,
i.e. they are 'indeterminate' in nature.
The majority of incidental lesions are benign cysts and although these can largely be characterised on the initial imaging examination,
some lesions remain indeterminate.
Approximately 40% of patients have at least one renal cyst incidentally discovered on abdominal CT and prevalence increases with age,
from <10% under 40 years to >60% over 80 years.2
The differential diagnosis for the indeterminate renal lesion is broad and largely includes:
- Hyperdense cysts
- Complex epithelial cysts
- RCC
- Oncytomas
- Fat poor angiomyolipomata (AML)
Studies suggest that up to 20% of surgically removed lesions less than 4 cm in diameter are benign.3 A more recent systematic review of 19 studies investigated benignity based on lesion size and revealed that 40% of excised lesions < 1 cm were in fact benign.4 In several surgical series,
oncocytoma accounts for approximately 50% of all small non-RCC resected lesions.3-5 Biopsy is therefore very useful in obtaining tissue diagnosis and preventing unnecessary intervention.
In general,
the management options for the small incidental renal lesion are discussed at a multidisciplinary setting and include:
- Leaving the lesion alone (for instance in the elderly,
co-morbid or palliative patient)
- Further imaging characterisation to exclude RCC
- Percutaneous biopsy
- Imaging surveillance
- Treatment: percutaneous ablation or nephron sparing surgery.