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Introduction

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Despite improved imaging techniques the diagnosis of mass lesions in the kidneys, many of which may be asymptomatic, continues to prove, and may be an increasing source, of clinical dilemma. Renal masses are now most frequently diagnosed as incidental findings. It is not uncommon that a lesion (often asymptomatic) of uncertain diagnosis is detected in one (or both) kidney(s) by one imaging modality which is not substantially clarified by other investigations. The urologist and patient are then confronted by a difficult situation. In deciding on the most appropriate course of action the patient needs to be advised of the potential diagnoses, their likelihood and risks, the optimal treatment in each case and the risks of both intervention (diagnostic and therapeutic) and observation.

Before the availability and widespread use of abdominal ultrasonography (US) and (CT), symptoms and/or signs of urinary tract pathology were the usual presentations of renal lesions. Masses detected by IVU were further investigated by ascending contrast-medium studies to outline the collecting systems of the kidneys, or by angiography. The latter was the principal mechanism to distinguish between simple cysts and lesions more suspicious of renal tumours. Cysts are avascular structures producing displacement of the otherwise normal vasculature of the surrounding parenchyma. However, RCCs were diagnosed on the basis of their characteristic hypervascularity that was unresponsive to vasoactive agents. Despite this, many mass lesions detected on IVU were explored, as a clear diagnosis could not be established by any other means. Surgery was therefore not uncommonly undertaken for cysts and other benign lesions of the kidney. The diagnosis of early RCC was difficult as a result of the frequent absence of symptoms and signs, and the relatively poor sensitivity of available investigations. Consequently, > 30% of patients presented with metastatic disease, at which stage the prognosis was extremely poor.

Therapeutic implications

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Surgery remains the only substantially effective treatment for RCC. Whilst the primary tumour can be excised, curing some patients with localized disease, the treatment of metastatic disease remains problematic. Neither chemotherapy nor immunotherapy appears to improve prognosis. Several preliminary studies have supported the possible benefit with the latter in patients with advanced disease, but these studies have not been supported by appropriate randomized trials and hence their value remains unproved [1]. The discovery of an otherwise asymptomatic and localized renal tumour therefore presents an opportunity for the patient to receive effective treatment that may not be possible at the time of onset of symptoms.

Despite a relative lack of progress in the treatment of RCC the spectrum of disease has altered substantially, entirely related to the earlier diagnosis of the disease that has occurred as a consequence of the widespread use of US and CT. This would appear to have resulted in not only the diagnosis of more patients at an earlier and more likely curable stage but also an increased incidence of this disease. Homma et al.[2], in a retrospective analysis from eight institutions, reported a progressive increase in incidentally detected tumours between 1975 and 1993, to represent over two-thirds of renal cancers. The authors indicated a decline in mortality from RCC at these study centres. However, as an institutional study, significant biases are possible in the study populations. Liu et al.[3] reported the kidney cancer incidence and mortality patterns in Canada since 1969 using data from the National Cancer Incidence Reporting System of Statistics Canada and the Canadian Centre for Health Information of Statistics Canada. The study period was 1969–1991 for incidence and 1969–1993 for mortality, with data from all provinces and territories except Quebec. The incidence of RCC doubled in men and almost doubled in women over the period 1969–1991. Increases were noted in all age groups, with the overall changes not just reflecting an ageing population. These increases were not accompanied by any substantial changes in mortality rates from RCC; they actually declined for both men and women aged 35–64 years. In a population-based study of RCC in Iceland between 1971 and 1990, there was no change in the incidence of incidentally detected tumours [4]. That study, which included all patients with a diagnosis of RCC in Iceland, showed no change in mortality during the study period. Therefore, although most urologists believe early diagnosis and therapy is of benefit, there is little conclusive evidence to support this view.

Many patients in whom renal lesions are incidentally detected have competing morbidity, based on their need for imaging studies. In many instances these are likely to have a more significant influence on the patients long-term outcome than their coincidentally detected renal tumour. For example, a patient with significant cardiovascular disease may have not only a limited long-term life expectancy from this disease but also a substantial risk of mortality related to any major operative procedure.

Diagnoses

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Despite the enhanced sensitivity of imaging techniques, particularly CT and US, patients with a preoperative diagnosis of RCC still undergo surgery and are found to have other pathology. Silver et al.[5] reviewed the final diagnosis of 636 nephrectomies performed between 1989 and 1996 on the basis of a preoperative diagnosis of RCC. Of these patients, 108 (16.9%) were found not to have had a RCC; there were 16 malignant tumours, including five sarcomas, six metastases and four TCCs. The most common benign masses were oncocytomas (49%). These are generally regarded as indistinguishable from RCC on imaging studies, and have a low but definite metastatic potential. Angiomyolipomas (13%) and cystic lesions (6.5% multilocular and 6.5% simple cysts) were other common lesions. The remaining patients (11%) had an assortment of other benign masses, including arteriovenous malformation, metanephric adenomas and juxtaglomerular tumour.

Cystic lesions

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Renal cysts are common and have been reported in half of patients over 50 years of age. Only on rare occasions does a cyst result in symptoms leading to its diagnosis, with the overwhelming majority representing incidental findings when CT or US is undertaken for unrelated reasons. The criteria required to make a confident diagnosis of a simple cyst on US are an anechoic (no internal echoes) lesion with a thin smooth sharply marginated wall showing posterior acoustic enhancement consistent with its size. Lesions that contain calcium, septations, irregular margins or any suspicious area require further study. On CT, simple cysts show sharp margination and demarcation from surrounding renal parenchyma, with smooth thin walls, homogeneous water density content throughout (− 10 to + 20 Hounsfield Units, HU) and no enhancement after intravenous administration of contrast medium. It is important that CT is undertaken before the administration of contrast medium, to enable an adequate assessment of possible contrast enhancement of the lesion, to ensure that findings such as calcification, small amounts of fat or recent haemorrhage within the mass will not be obscured by contrast media, and that high-density unenhancing renal cysts are not mistaken for solid masses. Partial volume averaging can also create a problem unless the section thickness is less than one half of the diameter of the lesion. With both modalities the smaller the lesion the more difficult it is to confidently characterize the lesion.

Bosniak [6] proposed a classification of cysts and cystic lesions of the kidney into four categories in an attempt to define those that require no further evaluation, and the risk or degree of suspicion of malignancy. Category I lesions are uncomplicated benign cysts with the US and CT features described above. Category II cysts are minimally complicated or high-density cysts showing smooth margins, thin septa (< 1 mm), minimal calcification and no enhancement after injection with intravenous contrast medium. In Bosniak's description these are benign, although some of the features may give rise to concern. Category III lesions are more complicated with some characteristics that may be consistent with malignancy. These include moderate calcification, irregular margins, thickened (> 1 mm) enhancing or nodular septa. Category IV cysts have irregular margins and/or solid enhancing elements most consistent with a malignant origin.

Hyperdense cysts are a specific subgroup of category II cysts warranting specific mention. These usually contain old blood and have a higher attenuation than surrounding renal parenchyma on unenhanced CT. The cysts tend to measure 60–70 HU with a range of 40–100 HU. After injection with intravenous contrast medium they appear either isodense or hypodense compared with the adjacent normal parenchyma. Bosniak felt that these benign lesions could be diagnosed using the following criteria:

  • the lesion is smooth, round, sharply marginated and homogeneous

  • no enhancement or changed configuration with injection of contrast medium

  • leqslant R: less-than-or-eq, slant  3 cm in diameter (although if > 3 cm and ultrasonographically appears fluid-filled is still probably a benign cyst).

Few studies have evaluated the diagnostic performance of the Bosniak classification, with the largest series to date reported by Siegel et al.[7]. In that study the clinical usefulness and interobserver variability of the Bosniak classification scheme was assessed by characterizing a series of 70 pathologically confirmed cystic lesions imaged with CT. Radiological features of the 38 benign and 32 malignant cystic masses were independently reviewed by three radiologists unaware of the final diagnosis, with the final classification based on the average. The distribution of the 70 lesions was 22 in category I (none malignant), eight in category II (13% malignant), 11 in category III (45% malignant) and 29 in category IV (90% malignant). All radiologists agreed on the category in 41 of 70 cases (59%). In only five of 16 category II or III cysts was the category consistent, compared with 36 of 51 (71%) in category I or IV. In their discussion the findings from three smaller series totalling 62 patients were also included. Of these, none of seven category I, four of 13 category II, 11 of 23 (48%) category III and 13 of 17 category IV cysts were malignant. Rare cases have also been reported of category I cysts being malignant [8].

Multilocular cystic nephroma is a benign renal lesion characterized by a well-developed capsule, fibrous stroma and septa that separate multiple epithelial-lined, cysts that do not communicate. A bimodal age distribution was reported, occurring most commonly in infants and young children and adults beyond the fourth decade. In the adult group there is a strong female predominance and clinical findings are not specific. No unequivocally reliable diagnostic signs can diagnose these lesions, excluding an underlying or coexistent malignancy with most having features of a Bosniak category III cyst [9].

Clearly several issues warrant consideration in cystic renal masses. The radiological features, which may be grouped into a classification system such as that proposed by Bosniak [6], provide no more than a guide to the likelihood of malignancy (or risk stratification). The series reported to date have comprised few patients compared with the prevalence of renal cysts, complicated cysts and RCC. In addition, these retrospective series were limited to patients with surgically removed lesions. Consequently, significant selection biases would be anticipated and may alter the distribution of lesions within each category. In none of the studies were any data presented dealing with the features and outcomes of patients with cystic lesions of all types, who did not undergo surgery. It is therefore possible that clinically significant malignancy is over-represented in all categories of cystic lesions.

In addition there appears to be considerable potential for variability in the interpretation of lesions, particularly with those in the intermediate ranges, for the risk of malignancy. Operator dependence may also influence the quality of images and therefore may be a further source of diagnostic difficulty with renal lesions. This is perhaps most marked with US, in which both patient factors and equipment limitations may also affect the value of an individual study. CT and MRI, whilst more reproducible, also depend on optimized imaging techniques. Among many factors the quality of results achieved with these modalities depends on the section thickness used, the level and timing of contrast medium enhancement of the tissues and the resultant image contrast generated between the lesion and background renal parenchyma. With conventional CT the evaluation of renal lesions, especially of small diameter, may be limited by partial volume-averaging effects. Helical and spiral CT offer some advantages by using overlapping intervals and thin collimation. It is important that images are not exclusively obtained in the corticomedullary phase of contrast enhancement. During this phase the resulting non-uniform nephrogram may fail to adequately detect or characterize both cysts and tumours. MRI currently appears to offer no advantage over the widely used combination of CT and US for the routine evaluation of renal masses. However, it provides an alternative imaging modality that can be used to evaluate renal masses in patients with renal insufficiency or iodine contrast medium allergy. Again, the timing of contrast medium administration (gadolinium chelates) is important, with hypoperfused and unenhancing lesions best delineated on delayed scans taken ≈ 90 s after injection [10]. A further limitation with MRI is its relative insensitivity and nonspecificity for identifying calcification, which can affect the interpretation of cystic and fatty lesions.

Angiomyolipomas and other lesions

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Angiomyolipomas are benign hamartomatous lesions with a characteristic echogenic appearance on US and intratumoral fat (< −10 HU) on CT. Although the overwhelming majority of renal masses containing fat are angiomyolipomas, the diagnosis of RCC should be considered in the presence of calcification. Helenon et al.[11] reported a series of unusual fat-containing tumours in 27 patients. Of these tumours, 15 comprised atypical or complicated angiomyolipomas and nine were found to be RCCs, with the remaining two tumours being benign lipoma and a liposarcoma. In the nine RCCs fat was present because of lipid-producing necrosis in a large RCC (two), intratumoral bone metaplasia with fatty marrow elements and calcification within the tumour (two), and entrapment of perirenal or sinus fat (five) by large irregular RCCs. The authors concluded from their review that malignancy should be suspected in renal lesions containing fat in cases with:

  • calcification within the lesion

  • large, irregular tumours invading the perirenal or sinus fat

  • large necrotic tumour with small foci of fat

  • association with non-fatty lymph nodes or venous invasion.

Because of the risk of haemorrhage, angiomyolipomas of > 5 cm are generally excised. These considerations are therefore mainly applicable to smaller asymptomatic lesions which even if felt to be entirely benign would generally be regarded as requiring follow-up with a view to intervention if there was a significant increase in size or symptoms.

Intrarenal or perirenal haematomas can usually be identified on CT. On occasions an underlying malignancy may be a contributing factor and follow-up imaging may be judicious. This should be considered if there has been no or minimal trauma, or if the haematoma persists for a long period [12]. Other lesions, including lobar nephronia, xanthogranulomatous pyelonephritis, renal infarction and anomalous or dysplastic renal tissue or disorders, may be diagnosed from the clinical history and radiological findings. Again repeated assessment may be necessary to follow the resolution or (lack of) progression of a particular lesion.

Percutaneous biopsy

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

It has been suggested that renal lesions may be indeterminate in up to 10% of cases with US alone and in 5–8% with the addition of CT [13]. In these situations strategies for further management include follow-up imaging to assess interval growth or change, percutaneous biopsy or cyst puncture and surgical resection. Whilst the latter may provide the only definitive answer (and treatment), the universal adoption of surgery for indeterminate cysts (and other indeterminate renal masses) would result in many unnecessary operations. Consequently many patients would be exposed to either the surgical risks of partial nephrectomy or the loss of an otherwise functional kidney.

Unfortunately, percutaneous aspiration or biopsy does not adequately exclude the possibility of malignancy to justify its routine use for indeterminate lesions. A review of percutaneous fine-needle aspiration or biopsy of renal masses suggest that the sensitivity for detecting malignancy and the specificity for determining benignity are 90% and 92%, respectively [13]. In the cases reported in published series, included in this review, 69% of the lesions were malignant, with a positive predictive value for cancer of 96%. However, the negative predictive value is only 80%; that would be regarded as inadequate in most settings to adequately exclude malignancy. The use of core biopsy may be associated with a lower false-positive rate, but the negative predictive value of core biopsy is no better than for fine-needle aspiration. Based on ex vivo studies, core biopsy has a sensitivity, specificity, positive predictive value, negative predictive value and undiagnostic specimen rate of 90%, 91%, 98%, 63% and 25%, respectively [13]. In these studies many of the lesions would have been diagnosed on radiological grounds alone. The predictive value of percutaneous aspiration or biopsy in indeterminate lesions has not been accurately assessed and could be expected to be somewhat lower than in series where lesions with a definite diagnosis are included.

Whilst its value or role in the diagnosis or exclusion of primary renal malignancies is questionable, percutaneous biopsy may be helpful in assessing patients in whom a renal lesion may be a manifestation of a systemic disease. If lymphoma is suspected or where the patient has had a previous malignancy of another site, percutaneous biopsy may be indicated. If a nonrenal malignancy is confirmed the patient avoids an open surgical procedure and/or nephrectomy, and may proceed immediately to more appropriate systemic treatment if indicated. Percutaneous biopsy may also be considered in patients who present with apparent metastatic RCC. However, this should be directed to metastatic sites rather than the primary lesion, to provide the best means of pathological staging. As a consequence patients who may have coexisting malignancies or have benign lesions in extrarenal sites are not denied the opportunity of potentially curative therapy. It would be expected that on occasions this may require surgical excision when an equivocal or undiagnostic biopsy is obtained.

Small renal masses

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

The clinical significance of small asymptomatic renal tumours is an issue that has emerged with the increased detection of renal lesions as incidental findings. A series of 43 small renal tumours (in 40 patients) that were < 3 cm in diameter when initially detected were followed with CT and US for a mean (range) of 3.5 (2–8) years. This series was reported on several occasions by Bosniak [14], with a progressive accumulation of patients and an extending follow-up. During observation the tumours had variable growth rates of 0–1.3 cm/year, with half having a growth rate of < 4 mm/year. The tumour was removed surgically in 29 cases, with histology confirming RCC in all except four cases reported as oncocytomas. The radiological appearance of the tumours in the remaining 14 cases was identical in growth rate and appearance to those that were removed. Over a 15-year period, 125 patients with RCC of leqslant R: less-than-or-eq, slant 3 cm were seen at the same institution [14]. In three patients (2.1%) metastatic disease was apparent at presentation. Therefore, a few RCCs are very aggressive at an early stage and are therefore not curable through surgical intervention. Despite this, none of the remaining patients (who presumably, although not specified, underwent surgical excision) developed subsequent metastatic disease. Nevertheless, it could be anticipated that in isolated cases observation of small renal tumours may result in a lost opportunity for curative treatment, as even during this phase patients may progress from localized to metastatic disease.

Whilst there were few patients and a limited follow-up in this series the reported results suggest that a conservative approach in patients with small (< 3 cm) lesions is associated with few risks in the short-term. However, a defined follow-up strategy with repeat imaging needs to be considered from the outset. In view of the slow growth of many small tumours this must extend for a considerable period. After initial imaging studies a reassessment at 3–6 months should exclude the possibility of a rapidly growing and potentially aggressive tumour (i.e. a clinically significant RCC) warranting reconsideration of surgical excision. If little change is evident, then repeat imaging at 12 monthly intervals may be viewed as reasonable. However, with this the original features and size of the lesion should be reviewed on each occasion, as subtle changes over time on sequential studies may be obscured unless early imaging is retained as a baseline.

Conclusions

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

Based on the limited information available it appears entirely reasonable that observation can be considered a valid option in the management plan of patients with small (leqslant R: less-than-or-eq, slant 3 cm) incidentally detected indeterminate renal masses. Provided a regular follow-up plan, including repeat imaging, is established then many patients will be spared unnecessary surgery and its potential complications, including perioperative death. This advantage must be considered together with the very small but definite risk of tumour metastasis. Young or otherwise healthy patients who would require extended follow-up may find this policy unacceptable in view of the risk of malignancy and the possibility of subsequent metastases. As no investigation can categorically confirm or exclude malignancy within a renal mass these patients may prefer to undergo either total or partial nephrectomy. In making this decision they must be warned of and accept the potential risks of surgery, as well as the possibility that the lesion may be either benign or clinically insignificant and would have resulted in no long-term effects if not removed.

Patients presenting with larger indeterminate lesions are a more difficult problem. Angiomyolipomas and multiloculated cystic nephroma are the most common such lesions. Whilst radiological features may make these lesions the most likely diagnosis, it may be difficult to categorically exclude the possibility of an underlying or associated malignancy, particularly with nephroma. In these cases the urologist and patient must determine the most reasonable approach, recognizing the risks and consequences of both intervention and observation. As with smaller lesions observation can be justified, accepting the small but definite risk of metastasis, providing a definite follow-up plan (which may continue for many years) is established at the outset.

It is clear that situations may arise when the diagnosis of a renal lesion cannot be resolved without surgical excision. However, this course of action must not be viewed as desirable or appropriate in all situations where an indeterminate mass is detected. If this were to be the case many benign or clinically insignificant lesions would be removed, with the patients exposed to the unnecessary risks, including potential morbidity, of surgery. The patient must be made aware of the potential limitations and risks associated with both surgery and non-operative approaches. With the latter it must be understood that whilst on the balance of probability the risks of surgery outweigh potential benefits, it is possible that an (undiagnosed) underlying malignancy may progress and affect both longevity and quality of life.

From a medicolegal perspective the issues to be confronted in dealing with a patient with a renal mass are the dangers of overlooking a RCC (which may or may not have had its ultimate clinical course altered by surgical intervention) and the risks (including potential morbidity) associated with surgical intervention for a benign renal lesion of no consequence other than its indeterminate nature. It must be accepted that a definite diagnosis may not possible without the surgical removal of the lesion. In addition, the results of all investigations are prone to both operator dependence and subjective variation in even experienced hands. Clinical decisions on the likely diagnosis and therefore management need to balance the potential risks and likely benefits of both intervention and observation for an individual patient, considering their general health and life expectancy. It must therefore be acknowledged that on occasions an individual patient will be adversely affected by a particular management plan, but that the decision was entirely justifiable and the most appropriate on the balance of probabilities at the time of presentation.

References

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author
  • 1
    Young RC. Metastatic renal-cell carcinoma: what causes occasional dramatic regressions? N Engl J Med 1998; 338: 1305 6
  • 2
    Homma Y, Kawabe K, Kitamura T et al. Increased incidental detection and reduced mortality in renal cancer – recent retrospective analysis at eight institutions. Int J Urol 1995; 2: 77 80
  • 3
    Liu S, Semenciw R, Morrison H, Schanzer D, Mao Y. Kidney cancer in Canada: the rapidly increasing incidence of adenocarcinoma in adults and seniors. Can J Public Health 1997; 88: 99 104
  • 4
    Gudbjartsson T, Einarsson GV, Magnusson J. A population-based analysis of survival and incidental diagnosing of renal cell carcinoma patients in Iceland. 1971–90. Scand J Urol Nephrol 1996; 30: 451 5
  • 5
    Silver DA, Morash C, Brenner P, Campbell S, Russo P. Pathologic findings at the time of nephrectomy for renal mass. Ann Surg Oncol 1997; 4: 570
  • 6
    Bosniak MA. The current radiological approach to renal cysts. Radiology 1986; 158: 1 10
  • 7
    Siegel CL, McFarland EG, Brink JA, Fisher AJ, Humphrey P, Heiken JP. CT of cystic renal masses: analysis of diagnostic performance and interobserver variation. Am J Roentgenol 1997; 169: 813 8
  • 8
    Ooi GC, Sagar G, Lynch D, Arkell DG, Ryan PG. Cystic renal cell carcinoma: radiological features and clinico-pathological correlation. Clin Radiol 1996; 51: 791 6
  • 9
    Castillo OA, Boyle Et Jr, Kramer SA. Multilocular cysts of kidney. A study of 29 patients and a review of the literature. Urology 1991; 37: 156 62
  • 10
    Kramer LA. Magnetic resonance imaging of renal masses. World J Urol 1998; 16: 22 8DOI: 10.1007/s003450050021
  • 11
    Helenon O, Merran S, Paraf F et al. Unusual fat-containing tumors of the kidney: a diagnostic dilemma. Radiographics 1997; 17: 129 44
  • 12
    Lund L, Christiansen UB, Hansen IM, Funder VT. Carcinoma presenting as intrarenal haematoma, either spontaneously or after minor trauma. Int Urol Nephrol 1994; 26: 497 500
  • 13
    Wolf Js Jr. Evaluation and management of solid and cystic renal masses. J Urol 1998; 159: 1120 33
  • 14
    Bosniak MA. Observation of small incidentally detected renal masses. Semin Urol Oncol 1995; 13: 267 72

Author

  1. Top of page
  2. Introduction
  3. Therapeutic implications
  4. Diagnoses
  5. Cystic lesions
  6. Angiomyolipomas and other lesions
  7. Percutaneous biopsy
  8. Small renal masses
  9. Conclusions
  10. References
  11. Author

D. Nicol, Director of Urology and Renal Transplantation, Princess Alexandra Hospital, Ipswich Road Woolloongabba, Brisbane, Queensland 4102, Australia.