Adult renal lymphangioma misdiagnosed as a simple renal cyst: A case report

Abstract

Renal lymphangioma is rare in adults and easily misdiagnosed due to non-specific clinical and imaging features. A 49-year-old Chinese male was admitted after routine physical examination detected a right renal cyst, with CT indicating a cystic lesion. He underwent laparoscopic surgery, and postoperative pathology confirmed renal lymphangioma. No recurrence was noted during 16-month follow-up. Clinicians should maintain high suspicion for this entity when evaluating adult renal cystic lesions, as pathological examination is the gold standard for diagnosis and surgical intervention yields favorable outcomes.

1. Introduction

Renal lymphangioma, also known as renal lymphangiectasia, is a rare congenital benign tumor of the lymphatic system. It is characterized by dysplasia of the perirenal lymphatic system and subsequent lymphatic vessel dilatation,¹ leading to the formation of unilocular or multilocular cystic masses. The condition typically occurs in infants before 2 years of age, while adult onset is relatively rare.² Lymphangiomas most commonly occur in the neck and axilla, but may also arise in the retroperitoneum, bones, mesentery, colon, spleen, and other sites. ^3,4 Renal lymphangioma is extremely rare, with an incidence of less than 1%,⁵ and has been rarely reported in the literature worldwide. Herein, we report a case of renal lymphangioma in an adult male admitted to our hospital. Combined with a review of relevant domestic and international literature, we analyze the etiology, clinical manifestations, imaging and pathological features, diagnosis, and treatment of this disease.

2. Case presentation

2.1. Patient information

A 49-year-old Chinese male patient was found to have a right renal cyst during a routine physical examination over 7 days prior to presentation. He denied symptoms of frequency, urgency, or dysuria; no hematuria, turbid urine, nausea, or vomiting was reported. He had no past history of kidney diseases or lymphatic system diseases, and had no prior history of systematic treatment for conditions related to this renal cyst; he maintained good general health and denied a family history of kidney diseases, lymphatic system diseases, or other hereditary diseases. He presented to the Department of Urology, the First Affiliated Hospital of Harbin Medical University, on June 2, 2024.

Physical examination: Blood pressure (BP): 122/86 mmHg; heart rate (HR): 100 beats per minute (bpm); respiratory rate (RR): 18 breaths per minute (bpm). No abnormalities were detected in the heart or lungs. There was no distension in the bilateral renal regions, and tenderness was absent at the bilateral costovertebral and costolumbar points. Percussion tenderness was present in the right renal region but absent in the left. No tenderness was observed along the bilateral ureteral tracts.

2.2. Auxiliary examinations

Laboratory tests: Neutrophil percentage: 47.30% (reference range: 50-70%); eosinophil percentage: 9.30% (reference range: 0.5-5%); basophil percentage: 1.40% (reference range: 0-1%); inorganic phosphorus: 0.90 mmol/L (reference range: 0.96-1.62 mmol/L). Routine blood and urine tests, urine bacterial culture, liver and kidney function, coagulation function, four infectious disease markers, blood glucose, and biochemistry were all unremarkable.

Auxiliary Examinations: Non-contrast enhanced 64-slice spiral computed tomography (CT) of the kidneys demonstrated normal size and position of both kidneys with clear contours. A round-like low-density lesion was detected at the inferior pole of the right kidney, with partial extrarenal protrusion, well-defined margins, and an arc-shaped calcification along its border. The lesion measured approximately 6.6 cm × 5.3 cm. No dilatation of the bilateral renal pelves or ureters was identified. The initial impression was right renal cyst. Subsequent 256-slice triphasic contrast-enhanced CT of the kidneys revealed a cystic lesion in the right kidney, with an arc-shaped high-density shadow along its posterior margin. No contrast enhancement was observed in the lesion following contrast administration. CT Conclusion: Right renal cystic lesion (Bosniak Category II) (Fig. 1).⁶

Fig. 1.

Panels A-C show non-contrast CT of the kidneys, with axial views demonstrating a cystic lesion in the right renal lower pole. Panels D-F depict contrast-enhanced CT images, revealing renal cortical enhancement with no enhancement within the cystic lesion.

2.3. Treatment course

Preoperative diagnosis was right renal cyst. After obtaining written informed consent from the patient, adequate preoperative preparation was completed, the patient underwent laparoscopic right renal cyst decortication under combined intravenous-inhalation anesthesia. After anesthesia took effect, the patient was placed in the left lateral decubitus position with the waist elevated; the surgical field was disinfected and draped. An incision of approximately 2 cm was made at the posterior axillary line under the right rib, and blunt dissection was performed through the subcutaneous tissue, external oblique muscle, internal oblique muscle, and transversus abdominis muscle down to the retroperitoneal space. The retroperitoneal space was further dissected with the index finger, and a self-made balloon catheter was inserted and inflated with 780 ml of air to expand the cavity. Additional incisions of 2 cm and 1 cm were made at the suprailiac region of the midaxillary line and the midabdominal region of the anterior axillary line, respectively. Under the guidance of the index finger, a 10-mm trocar and a 5-mm trocar were placed into the retroperitoneal cavity. After pneumoperitoneum establishment, the perirenal fascia was incised using an ultrasonic scalpel. Dissection revealed a large cyst (approximately 7 cm in diameter) at the lower pole of the right kidney, with mild loose adhesion to the renal parenchyma; the boundary was distinguishable without dense fibrous adhesion or invasive attachment. Following adequate mobilization of the cyst wall, the cyst was incised, revealing clear, transparent fluid inside. The cyst fluid was completely aspirated, and the cyst wall was resected along the junction of the cyst wall and renal parenchyma using the ultrasonic scalpel, followed by extraction with forceps. Secure hemostasis was achieved; no accessory injuries, active bleeding, or urinary extravasation were identified. Hemostatic gauze was placed in the surgical cavity, and a rubber drainage tube was inserted. The incisions were sutured and dressed with gauze, concluding the operation. The surgical specimen was sent for pathological examination, and the patient was safely transferred back to the ward with uneventful postoperative recovery. The total operative time was 74 minutes, with an estimated blood loss of 10 ml. The patient's vital signs remained stable intraoperatively and postoperatively. On postoperative day 1 (POD 1), 15 ml of light red bloody drainage was noted; on POD 2, the drainage volume decreased to 5 ml. The patient underwent wound dressing change and drainage tube removal, followed by discharge from the hospital. H&E staining revealed a piece of cyst wall-like tissue with a thin wall, with specimen dimensions of 1.8*1.5*0.5 cm. The pathological diagnosis was lymphangioma (vascular hamartoma) (from the cyst wall) (Fig. 2). Given the definitive pathological diagnosis, the patient declined immunohistochemical staining.

Fig. 2.

Renal lymphangioma under HE staining. The blue arrow indicates lymphocytic infiltration in the stroma, and the green arrow points to lymphatic endothelial cells of the cyst wall (magnification, × 100).

2.4. Follow-up

On POD 8, suture removal was performed. Complete wound healing was achieved on POD 25, and no recurrence was observed during a long-term follow-up of 18 months. The patient reported a good general condition with no subjective discomfort.

3. Discussion

3.1. Etiology

Lymphangioma is an extremely rare benign lesion. While international researchers can diagnose this condition using multiple methods such as immunohistochemistry, pathological examination, and ultrastructural analysis, its etiology and pathogenesis remain unclear. Some scholars have reported 45,X chromosomes with long arm abnormalities and deletions in affected patients, suggesting a malignant potential.⁷ Others have linked it to VHL gene mutations,⁸ representing a genetic-level investigation. Additionally, some researchers propose associations with factors such as infection, fibrosis, and lymphatic stasis. To date, most scholars believe that lymphangioma is caused by congenital lymphatic drainage dysplasia.⁹

3.2. Clinical manifestations

No statistically significant gender difference in the incidence of renal lymphangioma has been reported, and a small number of cases may have familial inheritance with non-specific clinical manifestations. Bilateral renal lymphangiomas are more common than unilateral ones,¹⁰ whereas our case presented with a single right-sided lesion that was relatively large in size and regular in shape.

Renal lymphangiomas are classified into localized and diffuse types based on the extent of lesions.¹⁰ The localized type is relatively rare and typically presents radiologically as single or solitary unilocular or multilocular cystic lesions; while cystic-solid or solid lesions are uncommon, and a small number are multiple or scattered. Most localized lesions are asymptomatic.

The diffuse type is more common, with extensive lesions mainly around the renal pelvis and perirenal region. Large lesions can cause compression or functional impairment, and common symptoms include abdominal distension, lumbago-abdominal pain, a palpable mass, hematuria, and proteinuria. Renal parenchymal compression may lead to renovascular hypertension or renal failure.¹¹ Cystic structures can also rupture, causing infection, hemorrhage, or collecting system obstruction with subsequent complications.

3.3. Imaging features

Imaging is crucial for the early diagnosis and management of renal lymphangiomas. B-mode ultrasound typically shows hypoechoic, well-defined cystic lesions in the renal parenchyma or perirenal space. On plain CT, these lesions appear as well-circumscribed, homogeneous low-density cysts, often oval with thin, smooth walls; septa may be seen in multicystic cases. Cortical thinning on CT suggests an increased risk of progressive renal impairment.³ Contrast-enhanced CT shows no enhancement of the cystic contents, although the walls and septa may enhance mildly, and adjacent renal parenchyma can be compressed. Large lesions may displace surrounding structures without infiltration.⁵ MRI demonstrates hypointensity on T1WI and hyperintensity on T2WI.¹² Due to its superior soft-tissue resolution, MRI is particularly useful for characterizing lesion components and distinguishing cystic from solid lesions. IVU usually shows preserved renal function but may reveal compression or deformation of the collecting system; ureteral involvement can cause hydronephrosis. Retrograde pyelography may show lymphatic dilation if pyelolymphatic backflow is present.¹³ In our case, the parenchymal lesion was preoperatively misdiagnosed as a simple right renal cyst. Large, thin-walled lymphangiomas with clear, homogeneous fluid can closely mimic simple renal cysts on CT.

3.4. Pathological features

Microscopically, smooth muscle cells are identified within the cyst wall, and the cystic lumen is lined with flattened endothelial cells. Both the cyst wall and lumen contain lymphocytes, with prominent lymphatic spaces. The cystic fluid is mostly serous and transparent or chylous in nature. Immunohistochemically, D2-40, CD31, and CD34 are valuable markers for identifying vascular-derived tumors.¹⁴

3.5. Differential diagnosis

Differential diagnosis of renal lymphangiomas primarily involves distinguishing them from non-lymphatic cystic lesions, such as cystic renal cell carcinoma (RCC), hydronephrosis, subcapsular hematoma, polycystic kidney disease, and simple renal cysts. Cystic RCC is characterized by thick, irregular cyst walls, numerous intra-cystic septa, and often extensive calcifications. Hydronephrosis predominantly involves the renal collecting system and can be differentiated via intravenous urography. Subcapsular hematomas are mostly post-traumatic, with CT attenuation values enabling distinction between blood and cystic fluid densities. Polycystic kidney disease typically presents as large, lobulated lesions with a predilection for bilateral involvement. Simple renal cysts manifest as water-like hypodense lesions with homogeneous internal density and regular, thin walls.

3.6. Comparative analysis of literature cases on renal lymphangioma in adults

To clarify the diversity of clinical features, diagnostic and therapeutic patterns of renal lymphangioma in adults, and to enhance the comprehensiveness of this study, we systematically searched for published cases of renal lymphangioma in adults in PubMed and other authoritative biomedical databases over the past decade. After rigorous screening, a total of 7 cases with complete clinical data were enrolled, including the present case. The core clinical characteristics of these cases were summarized and comparatively analyzed (Table 1).

Table 1.

Comparison of clinical characteristics between previously reported cases of adult renal lymphangioma and the current case.

Case No.	Age (yr)	Gender	Clinical Manifestations	Imaging Findings (CT)	Treatment
1	49	Male	Detected during physical examination, with no obvious symptoms	Cystic lesion in the right kidney with linear outward protrusion, homogeneous density, arc-shaped hyperdense shadow at its posterior margin, and no enhancement on contrast-enhanced scan	Laparoscopic right renal cyst decortication
2	45	Male	Positive percussion tenderness in bilateral renal regions and pitting edema of both lower extremities	Multilocular cystic lesions in the bilateral perirenal and renal sinus regions, showing diffuse distribution, with thin and uniform cyst walls, and no obvious enhancement of the cyst walls after contrast administration	Ultrasound-guided percutaneous drainage of bilateral perirenal cystic lesions15
3	35	Male	Intermittent low back pain on the right side and frequent urination	Multilocular cystic lesion in the right renal sinus, surrounding the ureteropelvic junction and extending beyond the kidney, partially encircling the proximal ureter, with no obvious enhancement after contrast administration	Ultrasound-guided percutaneous aspiration for diagnosis plus surgical resection16
4	67	Female	Accidently detected by ultrasound following a blunt contusion of the left hip	Perirenal fluid attenuation lesion with no enhancement on contrast-enhanced scan	Conservative management plus regular follow-up17
5	55	Male	Fever, chills, and tenderness in the left lumbar region	Multiple cystic lesions in the bilateral perirenal regions with thin walls and no enhancement on contrast-enhanced scan; complicated with urinary tract infection	Anti-infective therapy plus regular follow-up18
6	39	Female	Right lower abdominal pain	Multiple cystic lesions in the unilateral perirenal region, intrarenal area, and pelvic cavity, surrounding the ureter, with no enhancement on contrast-enhanced scan	Laparoscopic cystectomy19
7	52	Male	Painless gross hematuria	Polypoid soft tissue density shadow in the right renal sinus, with mild enhancement on contrast-enhanced scan	Ureteroscopic holmium laser resection20

4. Treatment

Renal lymphangiomas are benign, slow-growing lesions that are often asymptomatic. Asymptomatic patients with no complications and preserved renal function are generally managed with regular surveillance alone, whereas prompt surgical intervention is warranted for those with complications. Surgery aims to resect the lesion maximally while preserving normal renal parenchyma, with approaches including open, laparoscopic, and robot-assisted laparoscopic procedures (e.g., cystectomy, partial nephrectomy, or radical nephrectomy). For small lesions with no malignant features, ultrasound-guided percutaneous drainage and intracystic sclerotherapy yield satisfactory outcomes. Complex, extensively involved lesions may require combined surgery and sclerotherapy, with treatment individualized based on comprehensive assessment.

Surgical decision-making for this case was not based solely on cyst volume. Instead, in strict accordance with urological clinical guidelines for renal cysts (intervention indicated for cysts ≥4 cm in diameter), the decision was made through comprehensive evaluation of multiple factors: diagnostic uncertainty from the lesion's atypical imaging features, long-term complication risks of large cysts, renal function preservation, and the patient's active treatment preference.

5. Conclusion

In conclusion, renal lymphangiomas are rare entities with limited literature, resulting in incomplete clinical understanding of the disease. Additionally, their clinical manifestations and imaging findings lack specificity, rendering them prone to misdiagnosis or missed diagnosis by clinicians. Preoperative auxiliary examinations alone are insufficient for definitive diagnosis; instead, pathological examination of cyst wall tissue obtained via puncture or surgery is required to confirm the diagnosis early and prevent disease progression. Surgical treatment remains the most effective therapeutic modality for this condition.

CRediT authorship contribution statement

Feng Xiong: Writing – review & editing. Jianan Gong: Writing – original draft. Yifu Li: Writing – original draft. Yan Wang: Resources.

Ethics approval and consent to participate

Written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy. Published with written consent of the patient.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Availability of data and materials

If necessary, the relevant clinical data mentioned in this article can be obtained from the first author of the article.

Funding

This study received no specific funding from any funding agency in the public, commercial, or non-profit sectors.

Competing interests

The authors declare that they have no competing interests.