Renal (Kidney) Endometriosis
The first published case of kidney (renal) endometriosis was presented in 1943. (1) It came 26 years after the first published case of ureter endometriosis. (2) Less than two dozen case studies have been sporadically published over the years.
- Contraindicated: Not advised as a course of treatment or procedure.
- Hematuria: The presence of blood or blood cells in the urine.
- Hydronephrosis: cystic distension of the kidney caused by the accumulation of urine in the renal pelvis as a result of obstruction to outflow and accompanied by atrophy of the kidney structure and cyst formation.
- Loculated: having, forming, or divided into loculi a small chamber or cavity.
- Nephrectomy: The surgical removal of a kidney
- Septated: Divided by or having a septum (a dividing wall or membrane)
- (Ureter) Colic: an attack of acute (abdominal/flank/loin) pain localized in a hollow organ (ureter) and often caused by spasm, obstruction, or twisting.
(* All definitions obtained from: https://www.merriam-webster.com/dictionary)
The kidney does not have sensory nerves that project pain to the brain. Similar to the ureter, disease can be advanced before detection. The location of the lesion in the kidney determines if cyclical hematuria and/or hydronephrosis occurs. Hydronephrosis may also occur alternatively with accumulation of any sloughed debri that blocks the ureter, resulting in urine buildup in the kidney. Blockage within a ureter can lead to ‘ureteric colic’. Cases with renal endometriosis which have concurrent hydronephrosis have reported diffuse abdominal (3), flank/loin pain (4,5) or lowback ‘soreness’. (6)
Endometriosis of the kidney is difficult to differentiate from other masses based upon imaging alone (ie primary, metastatic cancers and other benign issues). A case report in 2015 reported the oversight of the patients history of cyclic dull back pain and hematuria with her menses. Based upon imaging only, a nephrectomy (kidney removal) was performed. The pathology report confirmed endometriosis. After-the-fact realization the patient’s case only necessitated partial kidney removal of involved tissue. (4) This demonstrates a classical characteristic of extrapelvic disease. When signs or symptoms DO present, the appear or significantly increase at the menses. This is referred to as ‘Catamenial’.
“…the imaging features of renal endometriosis do not facilitate accurate diagnosis.
….although ultrasound is useful to differentiate solid from cystic lesions and contrast enhanced computed topography increased the accuracy of the examination, it provides just little diagnostic information.”(5) – Giambelluca D et al. (2017)
A few years later, two more cases of renal endometriosis were reported. Diagnostic imaging was performed with an additional step. The result: an accurate preoperative diagnosis that conserved renal tissue. The two cases:
Case One: A 40 yo female with history of gastric ulcerated lesions and removal of one ovary due to endometriosis. Referred to imaging to rule out metastatic gastric tumor. Ultrasound noted a renal cyst. Contrast Enhanced Computed Tomography noted multiple nodular cysts (‘grapes’). An CECT Guided Needle Biopsy was added. A diagnosis of endometriosis was made.
Case Two: a 39 yo female with recent diagnosis of melanoma and remote history of ovarian endometrioma. A CECT noted ‘grape-like’ cortical lesions in the kidney. To differentiate between hemorrhagic cysts and metastatic lesions, a CECT Guided Needle Biopsy was added.* A diagnosis of endometriosis was made. (5)
(* Note: Metastatic malignancies were speculated in both cases, thus needle biopsy was not contraindictated. Also, traditional endometrioma’s of the ovary are often seen with a single compartment without presence of solid mass. ‘Typical’ endometriomas are unilocular (single compartment) with uniform ‘ground glass’ appearance of contents on ultrasound. Among older persons and older disease variations are observed to include multiple compartments (up to 4) and presence of solid substance (coagulated blood). (7)
The use of needle biopsy has improved the preoperative ability to differentiate endometriosis from metastatic cancers and other benign conditions. (32) However, some situations arise in which needle biopsy is contraindicated (ie. Renal Cell Carcinoma – primary cancers). One case presented with differential diagnosis of renal carcinoma, angiomyolipoma (AML) and endometriosis. A CECT noted the lesion was septated and appeared to have a vascular supply to the mass. A nephrectomy was performed. (6) The authors report:
“Our patient had a history of uterine myomectomy (fibroid removed), which is a risk factor for endometriosis. However, an initial evaluation of the huge renal tumor favored AML but renal cell carcinoma could not be excluded because of some vascularity on renal angiography. Under these conditions, it was reasonable to perform a right nephrectomy for further diagnosis and treatment.”(6) – Yuan-Hong J et al. (2013)
How is Renal Endometriosis treated?
With very few case reports to analyze, a ‘best treatment’ has not been developed. A couple common features among the cases reviewed here were found. The approach to each case was determined by ability to differentiate, prior to surgery, cancerous versus benign lesions.
- Two cases which could not rule out Renal Cell Carcinoma (a primary cancer) could underwent nephrectomy. (4,6)
- A single case with a large unidentifed cystic lesion of the cortical and calyx with hydronephrosis, underwent partial nephrectomy. (5)
- A single case with multiple ‘minute’ lesions and concurrent hydronephrosis of proximal ureter and renal pelvis underwent medical management with Danazol (duration and long term outcome unknown). Patient history renal colic suggested active lesion cyclical sloughing occluded the ureter. Endometriosis was confirmed with CECT guided needle. (3)
Two asymptomatic cases, without obstruction to urine production and drainage were monitored with regular imaging. No treatment was needed. (5)
Repetitive articles report endometriosis of the urethra represents approximately 2% of all lesions within the urinary tract (1). However, database searches have found very few accessible publications specific to urethral endometriosis. It is possible that the details of urethral endometriosis are included in case or small population studies that detail other areas of urinary tract disease. It is also important to clarify that lesions which have been classified as urethral, have not had direct involvement the internal length or opening of the urethra from base of the bladder to the external opening of the body. In agreement with Yarmonhamadi and Mogharabian (1), all publications acquired in our database search identified endometriosis within urethral diverticulum (2,3) or a vaginal lesion blocking flow through pressure on the posterior urethra wall (4).
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