Unusual renal displacement due to massive splenomegaly: a rare case report and review of literature

Abstract

Here, the case of a female patient in her late 60s, who presented to hospital for a scheduled health check relating to a history of myelofibrosis for the previous 9 years, is described. She recently experienced weight loss and abdominal distention. Physical examination revealed no abnormality or tenderness. Laboratory examination showed decreased blood cells, platelets and haemoglobin, and normal renal function. Ultrasound and computed tomography scans revealed a massively enlarged spleen and displaced and compressed left kidney with abnormal features, but normal right kidney. The patient declined surgery and her myelofibrosis was treated with ruxolitinib, with a recommendation of annual follow-up observation. Despite many recorded cases of left renal displacement caused by splenomegaly, it is very rare for the left kidney to be pushed across the midline to the right side by an enlarged spleen. This article explores the causes and management of this uncommon condition and provides a review of previous literature reports with the aim of enhancing the understanding of unusual renal displacement due to massive splenomegaly, and its potential treatment options.

Introduction

Splenomegaly-induced left renal displacement is a relatively infrequent occurrence that can be predicted based on the anatomical positions of the organs. The spleen is located within the peritoneum, whereas the kidneys are situated in the retroperitoneal space. There have been numerous recorded cases of left renal displacement due to splenomegaly, with most reporting vertical and sometimes medial displacement, but it is very rare for the left kidney to be pushed across the midline to the right side by an enlarged spleen.^1–5 In 1930, Ecarius first reported splenomegaly in a patient with haemangioendothelioma sarcoma causing the left kidney to shift across the midline, ⁶ and in 1938, Wilmer first described a concept of ‘crossed renal ectopia’, a phenomenon whereby one kidney crosses the midline and completely shifts to the other side. ⁷ Two cases of extensive kidney displacement caused by intraperitoneal pathology were first described in 1967, ⁸ and a case of splenomegaly causing the left kidney to move across the midline was reported in 1962, however, this case only involved the displacement of the left kidney to the other side of the midline and not a complete transposition to the right side. ⁹ In 2023, the present authors encountered a case of splenomegaly-induced left renal displacement to the right, due to bone marrow fibrosis. No published reports were found in the Chinese literature documenting complete rightward displacement of the left kidney caused by splenomegaly. To the best of the authors’ knowledge, the present case may be the first reported instance in China of left renal displacement to the right due to splenomegaly, filling a research gap in this area. The present article discusses the aetiology and treatment of this condition, with the aim of providing valuable insights for selecting appropriate treatment methods for future patients.

Case report

A female patient in her late 60s presented to hospital in July 2023 for a scheduled health check relating to a history of idiopathic myelofibrosis for more than 9 years at the time of presentation. She reported no history of hypertension, nephritis, or coronary heart disease, and reported having hepatitis B, but no history of infectious diseases, such as tuberculosis. There was no history of trauma, blood transfusion, or allergies to medications or food, and she underwent tonsillectomy in 2007.

Physical examination showed no abnormality except for a slight bulge in the abdomen with no tenderness or rebound tenderness throughout the abdomen. The liver was palpable 5 cm below the rib margin, and the spleen was palpable 10 cm below the rib margin. The patient was admitted to the Department of Haematology for tests on the day that she presented to hospital, with an admission diagnosis of primary myelofibrosis and splenomegaly. The laboratory evaluation showed a decrease in white blood cell count (4.6 × 10⁹/L), red blood cell count (2.04 × 10¹²/L), haemoglobin (79 g/L) and platelets (39 × 10⁹/L). Liver function was unremarkable, and renal function tests revealed creatinine level of 75 µmol/L and uric acid at 319 µmol/L, indicating normal renal function. Abdominal ultrasound on day 1 following hospitalization showed the left lobe of the liver measuring 112 mm in length and 87 mm in thickness, the right lobe measuring 160 mm in oblique diameter, the main portal vein diameter measuring 10 mm, and clear intrahepatic vessels with normal course. The liver parenchyma had homogeneous echogenicity and no definite masses were observed within the liver. The spleen was measured to be 192 mm in length and 75 mm in thickness, the splenic vein diameter was 6.7 mm, and homogeneous splenic parenchyma was observed, with no definite masses. The left kidney measured 127 × 82 mm, with almost complete occupation of the renal parenchyma by a hypoechoic area, thin renal cortex, and no obvious kidney stones. The right kidney measured 106 × 37 mm, with normal morphology, regular capsule, homogeneous parenchyma, and no stones or hydronephrosis (Figure 1(a)). A follow-up computed tomography (CT) scan 3 days later showed an enlarged spleen measuring 168 mm × 97 mm, with areas of decreased density and linear areas of increased density. The liver was enlarged, with disproportionate proportions of the lobes, and nodular high density within the liver parenchyma. No dilatation of the intrahepatic or extrahepatic bile ducts was observed. The left kidney was compressed and displaced, with dilatation of the renal pelvis and calyces, and thin renal parenchyma. The right kidney displayed normal size and morphology, with homogeneous density and no dilatation of the renal pelvis or calyces (Figure 1(b)). The patient's left kidney was atrophic and demonstrated marked hydronephrosis. As the patient declined surgical intervention, she was discharged after 13 days of hospital stay with the recommendation of an annual follow-up visit. The patient was initiated on a standard regimen of 10 mg ruxolitinib, orally, twice daily, with dose adjustments based on blood leukocyte levels. This regimen had been recommended in 2017, but was not initiated at that time due to prohibitive costs. In addition to ruxolitinib treatment, the patient was administered 0.5 g hydroxycarbamide, oral tablet, twice daily, dose-adjusted according to blood leukocytes. The patient also received 100 mg azacitidine, subcutaneous injection, once daily for 1 week at the end of 2023, and 100 mg azacitidine, subcutaneous injection, once daily for 4 days during summer 2024 (discontinued early due to intolerable side-effects).

Figure 1.

Diagnostic images from a female patient in her late 60s with an over 9-year history of idiopathic myelofibrosis, who presented for a scheduled health check: (a) ultrasound examination showing that the left kidney is compressed by the enlarged spleen, causing it to shift towards the right side; and (b) computed tomography image showing hydronephrosis in the left kidney, and the left kidney squeezed by the spleen across the midline and shifted transversely to the right side (axial plane).

This study was performed following the institutional ethical regulations and guidelines and was approved by the Institutional Ethics Committee of Gannan Medical University (approval number 2019106). The patient provided written informed consent for the publication of any potentially identifiable images or data included in this article. All patient details have been de-identified and the reporting of this case conforms to CARE guidelines. ¹⁰

Discussion

Displacement of the left kidney due to an enlarged spleen is an unusual phenomenon, and some researchers believe that renal displacement may not be directly related to splenomegaly. In 1969, Pirnar et al. ¹¹ reported changes in the position and configuration of the left kidney in several patients with splenomegaly. Such kidney changes result from extrinsic pressure by the enlarged spleen and their extent is proportional to the degree of splenic enlargement. A case in which splenomegaly caused anterior displacement of the left kidney, crossing the midline and resulting in duodenocolic flexure displacement, was reported in 1952, ¹² while in 1956, Engel suggested that renal displacement is typically caused by retroperitoneal masses. ¹³ A 1960 review of 552 cases of splenomegaly treated at a New York hospital between 1952 and 1957 reported that, among the 127 patients who underwent excretory urography, only 20 cases showed significant renal displacement attributable to splenomegaly. ¹⁴ Based on these 20 cases, along with an additional six cases since 1957, a total of 26 cases of left renal displacement caused by splenomegaly were identified, among which, 23 exhibited downward displacement, two showed upward displacement, and one demonstrated medial displacement. ¹⁴

Despite the ever-increasing use of selective arteriography and isotope scans that give precise anatomical and radiographic localization, there are few recent reports that analyse splenomegaly-related renal displacement. In the present study, a case of complete displacement of the left kidney to the right due to splenomegaly is described. Possible explanations for the lack of reports describing spleen-related rough translocation of the left kidney to the right side are: (1) from the anatomical position, the spleen is located in the left upper quadrant of the abdominal cavity, while the kidneys are positioned in the retroperitoneal space, posterior to and inferior to the spleen. The two are not at the same anatomical level, so the spleen is mostly seen to cause the left kidney to shift downward rather than completely transversely to the right; and (2) in the present case, CT showed that the spleen was located 10 cm below the rib cage, with a length of nearly 17 cm and a width of nearly 10 cm. The huge spleen completely occupied the left abdominal space and completely compressed the retroperitoneal space, resulting in no remaining space for the left kidney, except the right displacement. Such a large displacement of the left kidney led to a series of clinical manifestations: (1) continuous pressure of the spleen obstructed urine flow from the left kidney, leading to severe hydrops and atrophy of the kidney parenchyma; at the same time, the increased kidney volume would further aggravate the pressure; (2) the patient's most recent renal function review at hospital indicated that creatinine levels remained within the normal range, and the right kidney was considered to have been functionally compensated; and (3) despite such a large left kidney displacement and hydrops, the patient reported no obvious abdominal discomfort, suggesting that the left kidney displacement and hydrops were a long-term chronic pathological process. Because the patient declined surgical treatment, the hospital recommended follow-up observation.

Based on the present findings and previous reports, the following may be summarized: (1) early renal displacement may have no clinical symptoms and manifestations are mainly found in abdominal colour ultrasound examination. In addition to colour ultrasonography of the urinary system, abdominal CT, intravenous urography, retrograde pyelography, renal analysis imaging, and arteriography are available for assessing patients, and also play a role in the correct interpretation of the disease process; (2) for patients with only mild or no symptoms of splenomegaly, conservative treatment is usually used clinically. ¹⁵ However, in patients with roughly displaced spleen and kidney mentioned in the literature, after partial splenectomy, the affected kidney may automatically return to the renal fossa without fixation,^9,12 which cannot be applied to the present case. Ruxolitinib was used to actively treat the primary disease in the present case, and the spleen and kidney were not further treated; and (3) according to literature reports, the best method for excessive displacement of the left kidney caused by splenomegaly is to relieve the compression focus and remove part of the spleen. ¹⁶ However, if there are contraindications and other factors that make partial splenectomy impossible, conservative treatment may also be suitable.