Challenges of Renal Mass Diagnosis

Renal cancer is the most lethal tumor in genitourinary system. Diagnosis of renal cancer is a challenge all along the diagnostic pathway. If we are going to aim reduction of mortality by early detection, and by minimizing inclusiveness of treatment, many difficulties should be managed.

First, a great deal of experience is needed to manipulate patient's data as regard to renal masses. Decision about diagnostic and theraputic maneuvers should be based on knowledge and experience in urologic, oncologic and radiologic aspects of renal cancer. 

Clinical presentations of renal cell carcinoma depends on age and stage of disease. However, renal cell carcinoma are usually asymptomatic, and usually associated symptomes are attributed to other conditions that indicate an abdominal imaging and hence an accidental discovery of renal mass. Another important challenge is that physical examination have small role in the diagnostic procedure of renal mass, at least in comparison to earlier practice. An old triade of pain, mass and hematuria is not as common nowadays, and usually associated with larger, later stage masses.

Some masses present with symptoms of metastatic. A preference of secondaries to implant in lung make another challenge, because also lung cancer metastasis can home into the renal parenchyma. Mets can be found in liver, however liver enzymes can rise without metastasis in patients with RCC. 

Discrimination between benign and malignant pathology in renal tumors is the most serious and controversial issue in diagnosis of Ranal mass, as it is the basis of further work up or just close monitoring. Indeterminate renal masss by radiologic assessment indicates the need for pathologic examination via biopsy. The grey zone between benign and malignant criteria in CT lies inbetween two more confusing pathologic and radiologic criteria. For example, oncocytoma share radiologic features with chronophobe RCC. While angiomylipoma could be lipid poor and resembles conventional RCC. From the other hand, small tumors are more likely to harbour a benign pathology. Larger masses with central necrosis may looks like central scar of oncocytoma. 

Rupture of renal mass in not uncommon. It is known to occur in angiomyolipoma and RCC. However, it is more common in angiomyolipoma, especially more than 4 cm in diameter. A non-traumatic rupture and perinephric hematoma can occur that looks like Wunderlich syndrome. A challenge is to identify the mass and decide how will you treat.

Managing renal tumors includes further challenges. Large masses that extend into perinephric fat, or renal vein may need radical nephrectomy. Smaller masses can be excised sparing the healthier part or renal parenchyma. Small masses in older patients can be ablated  using ablative techniques. And in some specific well controlled situations, small masses can be actively surveilled. A cut edge between territories of suitable implementation of each treatment plan is far from being available. However, good assessment of each case, along with good understanding of benefits and limits of each intervention are succeful tools to make wise decision. 

Another challenge to Urologist during diagnosis is the assessment of patient's  kidney function. Chronic kidney disease is very common, and renal tumor can be an associations, a risk factor or a consequence. Determining intervention depends on the functional assessment of both and each renal units. 

Genetic workup of renal cell carcinoma is also another level of challenge. Genetic mutation in VHL and 3p losses of heterozygousity (which can be found in nearly all the tumor cells) are just a founding mutations, and are not predictors of progression or response to particular line of treatment. On the other hand, mutations that are associated with progressive course, or long response to systemic therapy occur in heterogeneous pattern in various locations of the tumor.

Summary:

1. RCC is lethal disease.

2. Diagnosis of RCC should be based on extensive oncologic, radiologic and pathologic backgrounds. 

3. FIndings of these modalities can not be used to predict others, as there is poor correlation between them.

4. Renal function assessment is an important part of renal mass diagnosis and treatment.

By:

Ahmed Bakr, MSc

Egypt