Cystic lesions containing enhancing soft tissue unattached to the wall or septa likely are malignant. Small cysts may grow into larger benign lesions, occasionally causing flank or abdominal pain, palpable masses, or hematuria. Simple cysts. Simple renal cysts on CT have homogenous low-attenuating fluid and thin nonenhancing walls without septa.
Malignant pheochromocytoma: indolent course and matching molecular characteristics on imaging
On ultrasound, simple renal cysts show spherical or ovoid shape without internal echoes, a thin smooth wall separate from the surrounding parenchyma, and posterior wall enhancement caused by increased transmission through the water-filled cyst. Inadequate ultrasound visualization or evidence of calcifications, septa, or multiple chambers calls for prompt renal CT.
It meets Bosniak criteria for a benign simple cyst class I and requires no further evaluation or follow-up. Colonoscopy detects multiple colonic polyps that are removed, and the patient does well. Mildly complicated cysts. Less diagnostic certainty characterizes cysts with mild abnormalities that keep them from being labeled as simple. Class II cysts may contain a few hairline septa, fine calcium deposits in walls or septa, or an unmeasurable enhancement of the walls.
A hyperattenuating but nonenhancing fluid also is described as category II.
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Menu Close. European journal of cancer Population based analysis of the increasing incidence of kidney cancer in the United States: evaluation of age specific trends from to The Journal of urology ; Renal cell carcinoma: links and risks. Int J Nephrol Renovasc Dis ; Clinical practice. Small renal mass. The New England journal of medicine ; Solid renal tumors: an analysis of pathological features related to tumor size. Renal cell carcinoma in relation to cigarette smoking: meta-analysis of 24 studies.
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Cancer ; Obesity and renal cell cancer--a quantitative review. British journal of cancer ; Risk factors for renal cell cancer: the multiethnic cohort. American journal of epidemiology ; Acquired renal cystic disease: implications for the urologist. Br J Urol ; As has been highlighted in the accompanying article on the Epidemiology and Etiology of Kidney Cancer , cancers of the kidney and renal pelvis comprise the 6 th most common newly diagnosed tumors in men and 10th most common in women.
Due to the increase in diagnosis of small renal masses and the general predilection for diagnosis of renal tumors in older adults typically diagnosed between age 50 and 70 years , the paradigm for treatment of renal tumors has focused on minimally invasive approaches and nephron sparing in the past few years. According to the American Urological Association guidelines on the management of stage 1 renal tumors, nephron sparing surgery partial nephrectomy is recommended. As with any tumor site, focal ablative therapies offer several potential advantages to traditional surgical approaches.
First, focal ablative therapies are less physiologically demanding on the patient than extirpative surgery.
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As a result, these may often be performed as ambulatory day surgical procedures with a much shorter convalescence and fewer complications when compared to laparoscopic partial nephrectomy. While long-term data are lacking, intermediate term data with a median follow-up of approximately 3. A number of indications have been well-recognized for the use of renal tumor ablation. Ablation is indicated for patients with small renal tumors who are: poor surgical candidates or at high risk of renal insufficiency. Patients may be at risk of renal insufficiency due to underlying nephron-threatening conditions such as diabetes or hypertension, due to a solitary kidney either congenital or due to prior nephrectomy , or due to oncologic factors such as bilateral tumors or hereditary syndromes which predispose to recurrent, multifocal tumors.
However, given the good outcomes of renal mass ablation in the treatment of small renal masses among these patients, a number of authors have now advocated the use of renal mass ablation in otherwise healthy patients. Non-surgical focal therapy refers to a therapeutic strategy, rather than a specific treatment modality. A number of different focal therapy modalities have been employed in the treatment of small renal masses.
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Foremost among these are cryoablation and radiofrequency ablation RFA. Prior to ablation, the American Urologic Association guidelines recommend biopsy of the renal mass either prior to ablation or at the time of treatment. Cryoablation, also known as cryotherapy, is the therapeutic use of extremely cold temperature. While first employed in the treatment of breast, cervical, and skin cancers, cryoablation has subsequently been used in the treatment of a variety of benign and malignant conditions. Initially, liquified air was used, then solidified carbon dioxide, liquid oxygen, liquid nitrogen, and finally argon gas.
Today, the majority of commercially available systems rely on argon gas. Ablation during cryoablation occurs during both the freezing and thawing phases of the treatment cycle. During freezing, the rapid decrease in temperature immediately adjacent to the probe causes the formation of intracellular ice crystals which lead to mechanical trauma to plasma membranes and organelles and subsequent cell death through ischemia and apoptosis.
During the thaw cycle, extracellular ice crystals melt leading to an influx of water back into the cells, resulting in cellular edema. In addition to these cellular effects, the freezing cycle results in injury to the blood vessel endothelium resulting in platelet activation, vascular thrombosis and tissue ischemia. The result of these process is coagulative necrosis, cellular apoptosis, fibrosis and scar formation.
Due to evidence that multiple freeze-thaw cycles led to larger areas of necrosis, the current treatment paradox suggests a double freeze-thaw cycle. For optimal cellular death, the preferred target temperature for cryotherapy is at or below o C. As temperatures at the edge of the ice ball are 0o C, most authors suggest that the ice ball extends at least 5 or 10mm beyond the edge of the target lesion.
In some cases, this will require the use of multiple probes. In contrast to cryotherapy which utilizes freeze-thaw cycles to induce cellular damage, radiofrequency ablation RFA relies upon radiofrequency energy to heat tissue until cellular death. Using monopolar alternating electrical current at a frequency of to kHz, RFA induces vibrations of ions within the tissue which leads to molecular friction and heat production. The resulting increased intracellular temperature leads to cellular protein denaturation and cell membrane disintegration.
The success of RFA treatment depends on the power delivered, the resulting maximal temperature achieved, and the duration of ablation. Unlike cryoablation which relies upon real-time imaging guidance, RFA may be guided by either temperature-based or impedance-based monitoring. Systems which rely on temperature-based guidance measure temperature at the tip of the electrode. However, they do not measure temperature within the surrounding tissue. Systems which rely on impedance-based guidance measure the resistance to alternating current the impedance.
These systems are calibrated to achieve a predetermined impedance level.
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