Renal cell carcinoma (RCC) is the malignancy of the renal tubular epithelium; with almost 50 % of cases being incidentally discovered. RCC comprises about 2-3% of all malignancies and about 85% of all solid renal tumours. 2% of RCC cases are bilateral and 16-25 % of cases are multi-centric (in the same kidney). The usual age of presentation is 50 to 70 years and males to females ratio of affection is 2:1. Lesions usually arise in the renal poles (upper more than lower) and they appear as exophytic mass(s) that alters the renal contour. Most lesions are solid and of soft tissue density that is hyper-dense, iso-dense or hypo-dense to renal tissue, yet it may show haemorrhage, necrosis, or fat and may be cystic. It rarely calcifies (less than 10%) but combination of fat and calcification suggests RCC rather than angiomyolipoma. The histopathological types of RCCs are: (1) Clear cell 70-80%, (2) Chromophil cell (papillary) 10-15%, (3) Granular cell 7%, (4) Chromophobe cell 5%, and (5) Spindle cell (sarcomatoid) 1-1.5%. Metastases may affect the lungs, liver, bone, adrenal glands, other kidney and brain. It has some association with von Hippel-Lindau * disease and tuberous sclerosis. The RCC is asymptomatic in many cases and presentation with the classic triad of gross haematuria, flank pain and palpable mass appears in less than 10% of cases 1 2.
Multi-phasic CT is the best imaging tool to depict RCCs. This includes a pre-contrast phase, arterial phase (15 seconds), cotico-medullary phase (60 seconds), nephrgarphic phase (> 80 seconds) and excretory or pyelographic phase (2 to 5 minutes). The RCC lesions appear as enhancing lesions (increase of more than 20 HU to pre contrast density) being hyper-dense to renal parenchyma in both nephrographic and pyelographic phases ¹ ². Seldom the lesion appears hypo-vascular (usually those of the papillary cell type) which may be mistaken for cysts in all imaging tools) 1.
Lesions may infiltrate renal vein or the calyces (where it may be mistaken for transitional cell carcinoma) and they may infiltrate surrounding muscles, diaphragm, colon as well as the IVC, liver, or right atrium in right sided lesions and pancreas, spleen (in left sided lesions) 1 2.
Although radical nephrectomy was considered for years the optimal treatment option, the results of numerous studies have demonstrated almost equivalent survival rates for patients who underwent radical nephrectomy and those who underwent partial nephrectomy (or nephron sparing surgery) for small renal neoplasms so elective partial nephrectomy is now a valid treatment approach 1 2 4. Partial nephrectomy or ablation (either by cryo, radio-frequency or microwaves) may be considered in lesions of small size and no extra renal spread 1 2. There is a limited role of chemotherapy and radiotherapy 1. Now, partial nephrectomy and radical nephrectomy can both be carried out either by open or laparoscopic approaches 2.
Vermooten back in 1950 was the first to suggest that localized RCC could successfully be excised while leaving a surrounding area of normal renal parenchyma 7.
Common imaging finding after surgery are: kidney displacement (posterior more than anterior), peri-nephric fat stranding, parenchymal defect, non-fat-containing post-operative collection fat stranding is seen more in open than in laparoscopic route. Collections are seen more in laparoscopic rather than open route, yet they resolve more rapidly with the open route. Occurrence and resolution of collection are not affected by age, sex, pre-operative lesion size or location 3.
Changes like posterior kidney displacement and peri-nephric fat strands (when seen in imaging) were mentioned by some as a prove of previous renal surgery. Fatty packing done by surgeon into the renal cortical defect after partial nephrectomy may be mistaken afterwards for angiomyolipoma and other haemostatic materials used in operation may show air bubbles and be mistaken for abscess 4.
* Eugen von Hippel: a German professor of ophthalmology and Arvid Vilhelm Lindau: a Swedish professor of pathology and bacteriology 6.