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.