renal_cysts
Table of Contents
renal masses and cysts
see also:
introduction
- it is common to have an incidental finding of cysts on kidneys on a CT KUB or CT abdo scan
- some should have a renal USS to further elucidate their nature and determine whether the patient should be referred to urology or renal medicine (nephrology)
- the Bosniak classification system has been created to help address this:
- Bosniak I or II ⇒ ignore
- Bosniak IIF ⇒ follow up - perhaps in 6 months
- Bosniak III or IV ⇒ excise
- the following imaging features indicate that a cyst is NOT simple:
- calcification
- hyperdense / high signal
- septations
- multiple locules
- enhancement
- nodularity / wall thickening
- indications for excision are thus one or more of the following:
- calcification status: enhancement, nodular and wall thickening
- hyperdens status: poorly defined heterogeneous enhancement; solid on USS;
- septations status: thick, irregular, nodular enhancement
- enhancement level: > 15 Hounsfield Units increase of the mass after contrast injection (indicates vascularity)
- multiloculated (unless due to infection)
- all nodules other than very small non-enhancing nodules
- wall thickening (unless due to infection)1)
.
Bosniak classification
Bosniak type I
- simple cyst, imperceptible wall, rounded
- work up : nil
- % malignant : ~ 0%
Bosniak type II
- minimally complex
- a few thin (< 1mm) septa
- may contain fine calcifications or a small segment of mildly thickened calcification.
- non-enhancing high-attenuation (due to to proteinaceous or haemorrhagic fluid) renal lesions of less than 3 cm are also included in this category
- these lesions are generally well marginated.
- work up : nil
- % malignant : ~ 0%
Bosniak type IIF
- minimally complex but requiring follow up.
- increased number of septa, minimally thickened or enhancing septa or wall
- thick or nodular calcium may be present
- hyperdense cyst that is:
- > 3 cm diameter
- mostly intrarenal (less than 25% of wall visible);
- no enhancement
- work up : needs ultrasound / CT follow up
- % malignant : ~ 25 %
Bosniak type III
- indeterminate, thick or multiple septations, mural nodule, hyperdense on CT (see 2F)
- treatment / work up : partial nephrectomy or RF ablation in elderly / poor surgical risk
- % malignant : ~ 54%
Bosniak type IV
- clearly malignant, solid mass with large cystic or necrotic component
- all the characteristics of category III lesions but also with enhancing soft tissue components independent of but adjacent to the septa
- treatment: partial / total nephrectomy
- % malignant : ~100%
DDx of renal cysts
- 33% of people older than 50 years develop renal cysts but most are simple cysts
- multicystic dysplastic kidney (MCDK) - developmental
- genetic:
- juvenile nephronophthisis (JNPHP)
- medullary cystic kidney disease (MCKD)
- glomerulocystic kidney disease (GCKD)
- Von Hippel-Lindau syndrome (VHLS) - CNS hemangioblastoma (Lindau tumor), bilateral and multicentric retinal angiomas, renal cell carcinomas, pheochromocytomas, islet cell tumors of the pancreas.
- tuberous sclerosis (TS)
- acquired:
- simple cysts
- acquired cystic renal disease - bilateral
- medullary sponge kidney (MSK) - usually benign, asymptomatic, congenital disorder often detected in 20-40yr olds, but may cause UTI, renal stones, haematuria and distal renal tubular acidosis type 1. Causes tubular ectasia and dilated collecting ducts rather than large cysts.
- renal angiomyolipomas
- malignant:
- cystic renal cell carcinoma (RCC)
renal_cysts.txt · Last modified: 2014/04/03 03:58 by 127.0.0.1