3 | DISCUSSION
Given their rarity, accurately diagnosing ERWTs prior to surgical resection remains challenging. The primary diagnosis in the present case was pheochromocytoma owing to the observed paroxysmal tachycardia and hypertension, but the normal urinary and plasma catecholamine levels did not support this diagnosis. We also considered neuroblastoma, as about 10% of neuroblastoma cases present with high BP[5], and there have also been case reports of neuroblastoma with hypertension and dilated cardiomyopathy, suggesting that this tumor type can cause the activation of the reninangiotensin aldosterone system[6]. However, about 90% of cases exhibited elevated urinary catecholamine metabolites[7], which was not evident in the present case. In addition to the above differential diagnosis, as some of these tumors arise within the pelvis, they may be incorrectly diagnosed as ovarian cysts or pelvic teratomas[8], but these rarely cause high blood pressure and heart failure. In general, only postoperative pathological analyses ultimately lead to definitive ERWT diagnoses. Per Beckwith and Palmer[9], ERWTs are diagnosed based upon the following criteria: a primary extrarenal tumor exhibiting a primitive blastematous spindle or round cell component, with an abortive, embryonal tubular, or glomeruloid structure and no evidence of teratoma or renal carcinoma. WT1 is the most sensitive immunohistochemical marker for Wilms tumor diagnosis, being detectable in > 90% of cases[10]. Ultimately, in this medical record, pathological results were instead consistent with an ERWT, with WT1 positivity being observed upon immunohistochemical staining, diagnosis is definitive. Another rare aspect of this case is that the tumor arose next to the undescended testis. There have only been a few prior reports of paratesticular ERWTs to date[11].
To date, there have only been six published cases of Wilms tumor patients suffering from hypertensive cardiomyopathy and subsequent CHF[12-17], with all of these cases being tied to primary intrarenal tumors. This report is the first to describe hypertension and CHF in a patient with an ERWT. The two mechanisms that are generally believed to contribute to hyperreninemia are Wilms tumor-mediated renin production and the tumor-mediated compression of the renal artery. Immunohistochemical staining of the tumor tissues from five Wilms tumor patients revealed detectable renin expression in the blastemal portion of the tumor tissue, supporting a model wherein the production of renin by these tumors is the primary driver of hypertension[18]. In the present case, preoperative renin levels were significantly elevated but rapidly returned to normal ranges within the days following surgery. Moreover, the tumor was located within the pelvis, thus precluding the potential for renal artery compression. We thus speculate that this tumor was capable of directly secreting renin, contributing to secondary complications including dilated cardiomyopathy, hypertension, and CHF. Tumor resection alleviated the observed deterioration in cardiac function, with gradual postoperative improvements in LV contractility, performance, and function. It is thus evident that tumor-induced hyperreninemia led to increased angiotensin II and aldosterone, resulting in hypertension and hypertensive cardiomyopathy. However, Perry et al [19] reported cases of Wilms tumors with dilated cardiomyopathy without hyperreninemia. They note that in addition to renin, there may be other vasoactive mediators that can contribute to dilated cardiomyopathy and CHF, but further research will be required to confirm this possibility.
When assessing patients presenting with pelvic tumors complicated by heart failure and hypertension, ERWTs must be considered in the differential diagnosis. Hypertension can frequently lead to the potential for misdiagnosis in these cases, underscoring the need to raise awareness of this rare complication of such extrarenal tumors. Preoperatively controlling BP is critical in the treatment of ERWTs patients, and the use of angiotensin-converting enzyme inhibitors may represent the most effective means of treating renin-mediated hypertension in these patients prior to surgical intervention[20]. In the present case, the patient exhibited pronounced hypotension following the administration of low-dose captopril (0.3 mg/kg), suggesting that even lower doses should be used in the future in an effort to prevent this complication. The overall prognosis of ERWT patients is similar to that of intrarenal Wilms tumor patients, with surgical resection of the tumor representing the most effective means of controlling tumor growth and associated complications. Following tumorectomy, the prognosis of affected patients is generally good. However, in patients presenting with unexplained pelvic or abdominal tumors, early diagnosis and prompt surgical intervention are recommended to prevent or mitigate hypertension, dilated cardiomyopathy, and heart failure, thus contributing to a better patient prognosis.