"Could Patient Age and Gender, along with Mass Size, Be Predictive Factors for Benign Kidney Tumors?": A Retrospective Analysis of 307 Consecutive Single Renal Masses Treated with Partial or Radical Nephrectomy.

Due to the increased use of common and non-invasive abdominal imaging techniques over the last few decades, the diagnosis of about 60% of renal tumors is incidental. Contrast-enhancing renal nodules on computed tomography are diagnosed as malignant tumors, which are often removed surgically without first performing a biopsy. Most kidney nodules are renal cell carcinoma (RCC) after surgical treatment, but a non-negligible rate of these nodules may be benign on final pathology; as a result, patients undergo unnecessary surgery with an associated significant morbidity. Our study aimed to identify a subgroup of patients with higher odds of harboring benign tumors, who would hence benefit from further diagnostic examinations (such as renal biopsy) or active surveillance. We performed a retrospective review of the medical data, including pathology results, of patients undergoing surgery for solid renal masses that were suspected to be RCCs (for a total sample of 307 patients). Owing to the widespread use of common and non-invasive imaging techniques, the incidental diagnosis of kidney tumors has become increasingly common. Considering that a non-negligible rate of these tumors is found to be benign after surgery at pathological examination, it is crucial to identify features that can correctly diagnose a mass as benign or not. According to our study results, female sex and tumor size ≤ 3 cm were independent predictors of benign disease. Contrary to that demonstrated by other authors, increasing patient age was also positively linked to a greater risk of malign pathology.

A Rare Isolated Kidney Cyst: Hydatid Cyst.

Hydatid disease is a parasitic disease caused by Echinococcus granulosus or Echinococcus multilocularis. It is still a serious public health problem in endemic regions such as the Mediterranean basin. Since the complaints caused by the cysts are non-specific and routine laboratory tests do not always yield positive results, diagnosis may be difficult. While liver involvement is present in 70% of cases, larvae escaping from the filtration of the liver cause pulmonary disease in 25% of cases. Although the prevalence of kidney involvement in all hydatid cysts is approximately 2-4%, and isolated kidney involvement is extremely rare at 1.9%. In this case report, we present an extremely rare pediatric case of isolated renal hydatid cyst, the diagnosis of which was somewhat delayed.

"To Be or Not to Be Benign" at Partial Nephrectomy for Presumed RCC Renal Masses: Single-Center Experience with 195 Consecutive Patients.

In daily medical practice, an increasing number of kidney masses are being incidentally detected using common imaging techniques, owing to the improved diagnostic accuracy and increasingly frequent use of these techniques. As a consequence, the rate of detection of smaller lesions is increasing considerably. According to certain studies, following surgical treatment, up to 27% of small enhancing renal masses are identified as benign tumors at the final pathological examination. This high rate of benign tumors challenges the appropriateness of surgery for all suspicious lesions, given the morbidity associated with such an intervention. The objective of the present study was, therefore, to determine the incidence of benign tumors at partial nephrectomy (PN) for a solitary renal mass. To meet this end, a total of 195 patients who each underwent one PN for a solitary renal lesion with the intent to cure RCC were included in the final retrospective analysis. A benign neoplasm was identified in 30 of these patients. The age of the patients ranged from 29.9-79 years (average: 60.9 years). The tumor size range was 1.5-7 cm (average: 3 cm). All the operations were successful using the laparoscopic approach. The pathological results were renal oncocytoma in 26 cases, angiomyolipomas in two cases, and cysts in the remaining two cases. In conclusion, we have shown in our present series the incidence rate of benign tumors in patients who have been subjected to laparoscopic PN due to a suspected solitary renal mass. Based on these results, we advise that the patient should be counseled not only about the intra- and post-operative risks of nephron-sparing surgery but also about its dual therapeutic and diagnostic role. Therefore, the patients should be informed of the considerably high probability of a benign histological result.

Infection as a Differential Diagnosis of Solid Retroperitoneal Masses: A Case Series and Review of the Literature.

The differential diagnosis of retroperitoneal masses includes a variety of benign and malignant conditions, among which infections constitute a significant subgroup. Familiarity with these infectious pseudotumours could facilitate prompt diagnosis. In this report, we describe three patients with an infectious pseudotumour, which was clinically and radiologically highly suggestive of a neoplasm. The first patient was a 62-year-old woman with a history of Richter syndrome, who seven months after allogeneic haematopoetic stem cell transplantation from an unrelated donor presented with a renal mass. A renal biopsy at that time revealed necrotic tissue. The patient displayed multiple relapses of Richter syndrome (for which she received also chimeric antigen receptor T-cell therapy salvage chemotherapy) and remissions of the lymphoma as well as an Aspergillus pneumonia for which she was treated with intravenous ambisome and afterwards oral posaconazole. Since the renal mass persisted and to exclude malignancy, nephrectomy was performed which revealed the presence of fungal hyphae. The second patient was a 51-year-old man with a history of a low-grade non-muscle-invasive bladder urothelial carcinoma, who after Mycobacterium bovis Calmette-Guerin instillation presentedwith fever and a suspicious renal mass. A partial nephrectomy was performed. Intraoperative frozen section analysis and routine histology suggested a Mycobacterium bovis-associated lesion, which was confirmed by polymerase chain reaction (PCR) analysis. The third patient was an 85-year-old man who presented with loss of appetite, fatigue, and significant weight loss (24 Kg in less than a year) as well as a travel history. The laboratory tests showed a low sodium and a high potassium level. CT scans revealed a solitary lesion in the right lung, a small liver lesion as well as bilateral adrenal lesions. A CT-guided biopsy revealed the presence of Histoplasma capsulatum, which was confirmed by PCR analysis. A retrospective review of all parameters indicates that all three patients presented with some risk factors, such as immunosuppression, travel, or clinical history that could raise the suspicion of infection in order to be included in the differential diagnosis, thus providing an additional tool for timely diagnosis.

Active Surveillance for Renal Angiomyolipoma Less Than 4 Centimeters: A Systematic Review of Cohort Studies.

The aim of this review is to evaluate the current evidence regarding the best management in terms of active surveillance of angiomyolipoma (AML) cases less than 4 cm, particularly the optimal timing of active surveillance. In addition, we aimed to describe their initial size, clinical presentation, and growth rates. The present systematic review included prospective and retrospective studies that evaluated and followed up patients with AML through active surveillance. Studies were retrieved through an online bibliographic search of the Medline database via PubMed, SCOPUS, Web of Science, and Cochrane Library from their inception to January 2022. Seven studies were included in the present systematic review. Concerning the active surveillance protocol, only four studies describe the frequency of active surveillance and the utilized imaging modality. Some studies followed up lesions by ultrasound annually for two to five years, while other studies followed-up patients twice for the first year, then annually for a median follow-up period of 49 (9-89) months. The used modalities were ultrasound, CT, and magnetic resonance imaging (MRI). Notably, the incidence of spontaneous bleeding was consistent across the included studies (ranging from 2.3 - 3.1%), except for one study which showed an incidence rate of 15.3%. In terms of the need for active treatment, the rate of active treatment was slightly higher in some studies than the others. However, this variation could not be considered clinically relevant to favor one surveillance strategy over the other. We concluded that active surveillance is the first line of management in all small asymptomatic ALMs. ALMs less than 2 cm do not require active surveillance. The current published literature suggested that active surveillance for two years may provide the same benefits as a five-year surveillance strategy, with fewer radiation hazards and less socioeconomic burden.

Pulmonary lymphangioleiomyomatosis with an associated giant renal angiomyolipoma.

Pulmonary lymphangioleiomyomatosis (LAM), a rare, progressive disease predominantly affecting the lungs of women of reproductive age, is often associated with renal angiomyolipoma (AML). We report the case of a 29-year-old female patient who presented to our obstetrics department at 37 weeks' gestation, complaining of abdominal pain, and constipation. Ultrasound noted a viable singleton with a large left-sided abdominal mass. After undergoing a caesarean section, she was referred to our urology department to assess her flank mass further. Computed tomography demonstrated a large, exophytic left renal mass measuring 22 cm x 16 cm x 13 cm, suggestive of an AML and numerous bilateral pulmonary cysts. A diagnosis of LAM and associated unilateral giant renal AML was made. As soon as she had fully recovered from her caesarean section, we removed the huge AML via a standard left-sided open nephrectomy without incident. We report this rare case of giant AML associated with LAM and review the literature about the association of these two conditions.

A Radiomic-based Machine Learning Algorithm to Reliably Differentiate Benign Renal Masses from Renal Cell Carcinoma.

BACKGROUND: A substantial proportion of patients undergo treatment for renal masses where active surveillance or observation may be more appropriate. OBJECTIVE: To determine whether radiomic-based machine learning platforms can distinguish benign from malignant renal masses. DESIGN, SETTING, AND PARTICIPANTS: A prospectively maintained single-institutional renal mass registry was queried to identify patients with a computed tomography-proven clinically localized renal mass who underwent partial or radical nephrectomy. INTERVENTION: Radiomic analysis of preoperative scans was performed. Clinical and radiomic variables of importance were identified through decision tree analysis, which were incorporated into Random Forest and REAL Adaboost predictive models. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the degree of congruity between the virtual diagnosis and final pathology. Subanalyses were performed for small renal masses and patients who had percutaneous renal mass biopsies as part of their workup. Receiver operating characteristic curves were used to evaluate each model's discriminatory function. RESULTS AND LIMITATIONS: A total of 684 patients met the selection criteria. Of them, 76% had renal cell carcinoma; 57% had small renal masses, of which 73% were malignant. Predictive modeling differentiated benign pathology from malignant with an area under the curve (AUC) of 0.84 (95% confidence interval [CI] 0.79-0.9). In small renal masses, radiomic analysis yielded a discriminatory AUC of 0.77 (95% CI 0.69-0.85). When negative and nondiagnostic biopsies were supplemented with radiomic analysis, accuracy increased from 83.3% to 93.4%. CONCLUSIONS: Radiomic-based predictive modeling may distinguish benign from malignant renal masses. Clinical factors did not substantially improve the diagnostic accuracy of predictive models. Enhanced diagnostic predictability may improve patient selection before surgery and increase the utilization of active surveillance protocols. PATIENT SUMMARY: Not all kidney tumors are cancerous, and some can be watched. We evaluated a new method that uses radiographic features invisible to the naked eye to distinguish benign masses from true cancers and found that it can do so with acceptable accuracy.

Renal oncocytoma with vascular invasion: a series of 22 cases.

Renal oncocytomas are benign neoplasms that are often excised, as clinically they cannot be distinguished with certainty from renal cell carcinoma. One of the least common findings in oncocytomas is vascular invasion, and their behavior is not well characterized with only reports of isolated examples and smaller case series. Whether vascular invasion is acceptable for the diagnosis of oncocytoma still remains controversial, even amongst genitourinary pathologists with expertise in renal tumor pathology. Of 1474 cases of renal oncocytoma identified at 3 large medical centers, 22 (1.5%) had vascular invasion. Patients included 12 men and 10 women with an average age at diagnosis of 67.5 years (range, 48-91 years). Thirteen cases showed large vessel invasion, and the remainder involved medium or small vessels. Tumor was grossly visible in the renal vein in 2 cases. Clinical data were available on 16 of the 22 cases with an average follow-up time of 29.9 months (range, 7.5-94.5 months). Of the cases with clinical follow-up, all but one individual was alive. All living individuals were free of recurrence or metastatic disease at the time of last follow-up. Our cohort showed no metastasis or recurrence and overall survival of 94.7% at 2.5 years following diagnosis, supporting the finding that vascular invasion does not alter the favorable prognosis of oncocytoma. The presence of vascular invasion should not lead to any uncertainty about the diagnosis in an otherwise typical oncocytoma.

Incidental solid renal mass in a cadaveric donor kidney.

The number of patients living with end-stage renal disease (ESRD) is increasing in our country and demand for renal grafts is ever increasing. Cadaver renal transplantation is being established as a viable supplement to live transplantation. We present a case where a mass lesion was encountered in the donor kidney from a cadaver. Enucleation of the lesion was done and we proceeded with the grafting. Histopathological examination showed a 'Renomedullary interstitial cell tumour', a rare benign lesion. Post transplant, the renal function recovered well and the patient is asymptomatic. Such incidental renal masses present an ethical dilemma to the operating surgeon.