Post-nephrostomy hernia of Grynfeltt–Lesshaft lumbar triangle causing obstructive uropathy

A 35-year-old male presented to the emergency department with right lumbar pain. Laboratory tests revealed renal insufficiency [urea level = 7.9 mmol/L (normal range: 3.2–7.4); creatinine level = 162 µmol/L (normal range: 64–110); glomerular filtration rate = 46.81 mL/min/1.73m² (normal range: 90–120)]. The patient’s medical history included left renal agenesis and right vesicoureteral reflux treated in the neonatal period at one month of age with pyelostomy, followed by closure and right ureteral reimplantation at one year of age. There was no history of other lumbar procedures.

Initially, an ultrasound examination was conducted, revealing moderate dilation of the right urinary tract. Subsequent contrast-enhanced computed tomography (CT) confirmed the dilation and identified a right lumbar hernia (LH) located in the Grynfeltt–Lesshaft triangle (GLT). This hernia contained perirenal posterior fat tissue and the proximal ureter, which exhibited an angle change at the site of the hernia; however, the distal ureter appeared normal upon re-entry into the retroperitoneal space. Delayed renal function was also observed. Furthermore, the absence of the left kidney was noted, consistent with renal agenesis (Figures 1a, 1b and 1c).

Background

Lumbar hernias (LH) are rare posterolateral abdominal wall defects, which may be congenital or acquired (80%) [1,2]. Acquired hernias are classified as primary or secondary (25%) [1], with secondary hernias usually occurring post-surgery. Approximately 98% of LHs develop in the superior triangle or GLT and the inferior or Petit triangle [3]. The GLT, found in 93.5% of individuals, is an inverted triangle bordered laterally by the internal oblique muscle, medially by the erector spinae muscle group, and superiorly by the 12th rib. Its floor consists of the transversalis muscle aponeurosis, while the roof is constituted by the latissimus dorsi muscle.

Anatomically, the factors influencing hernia development include the triangle’s size and shape, quadratus lumborum and serratus posterior muscles dimensions, and the length and angulation of the 12th rib. Consequently, hernias in this region are more prevalent in short and obese individuals, as these characteristics are associated with horizontal rib orientation and a larger triangle [3,4].

Clinical Perspective

LHs typically present as a palpable mass in the lumbar region, which may be asymptomatic or associated with varying degrees of pain. Additional symptoms may include nausea, vomiting, abdominal bloating, lower back discomfort, and signs of intestinal obstruction if bowel contents are incarcerated or strangulated. If renal contents are involved, urinary obstruction may lead to kidney failure.

LHs can be classified as incarcerated or strangulated, with surgical repair recommended upon diagnosis; however, only 9% present acutely, requiring urgent intervention. Differential diagnoses for LHs include lipoma, soft tissue tumours (e.g., fibromas), haematomas, abscesses, renal tumours, hydronephrosis, rhabdomyomas, sarcomas and muscle hernias.

Imaging Perspective

Although the diagnosis of LHs is primarily clinical, CT should be routinely employed in the evaluation of affected patients. CT is considered the gold standard for diagnosing LHs, as it effectively visualises the muscular and fascial layers, as well as the defects and herniated contents. This imaging modality can differentiate muscle atrophy from true hernias and is valuable in the differential diagnosis of conditions such as tumours. Conventional radiographs may also be useful for identifying radiological signs of intestinal obstruction.

Outcome

LHs located in the GLT should be included in the differential diagnosis of patients with low back pain and renal failure. Timely suspicion and accurate diagnosis are essential to prevent complications and avoid unnecessary invasive procedures.

Take Home Message / Teaching Points

If a LH is suspected, it is crucial to conduct a CT to characterise the affected wall layers and herniated contents, as well as to assess for signs of hernia-related complications.

Written informed patient consent for publication has been obtained.