Giant exophytic renal angiomyolipoma masquerading as a retroperitoneal liposarcoma: A case report and review of literature

A Large Retroperitoneal Liposarcoma Mimicking an Angiomyolipoma on Pre-operative Imaging: A Case Report

Retroperitoneal masses present a diagnostic challenge due to their elusive origin and varied clinical manifestations. Among these masses, retroperitoneal liposarcomas, rare tumors of mesenchymal origin, often grow asymptomatically until compressing surrounding structures, necessitating accurate and early diagnosis. Renal angiomyolipomas (AMLs) have also been reported to mimic retroperitoneal liposarcomas on radiographic imaging, further complicating diagnostic processes. The presented case report describes a rare instance of a large well-differentiated liposarcoma that mimicked a renal angiomyolipoma on imaging in a 58-year-old male patient. The patient initially presented with worsening abdominal distension, early satiety, and left-sided flank pain for the past year. Radiographic imaging revealed a large mixed echogenic lesion measuring 22 x 13 cm in the left kidney with diffuse fat contribution, suspected to be a giant renal angiomyolipoma. The patient underwent selective arterial embolization by interventional radiology. Follow-up imaging eight months later showed an increase in the size of the mass, raising suspicion of a liposarcoma. Surgical resection of the mass and a radical left nephrectomy were performed, with final pathology confirming the diagnosis of a well-differentiated liposarcoma. This case highlights the importance of accurate diagnosis and the potential for liposarcomas to mimic other masses on imaging, despite their rarity.

Deep Learning Plus Three-Dimensional Printing in the Management of Giant (>15 cm) Sporadic Renal Angiomyolipoma: An Initial Report

Objective

To evaluate the feasibility and effectivity of deep learning (DL) plus three-dimensional (3D) printing in the management of giant sporadic renal angiomyolipoma (RAML).

Methods

The medical records of patients with giant (>15 cm) RAML were retrospectively reviewed from January 2011 to December 2020. 3D visualized and printed kidney models were performed by DL algorithms and 3D printing technology, respectively. Patient demographics and intra- and postoperative outcomes were compared between those with 3D-assisted surgery (3D group) or routine ones (control group).

Results

Among 372 sporadic RAML patients, 31 with giant ones were eligible for analysis. The median age was 40.6 (18-70) years old, and the median tumor size was 18.2 (15-28) cm. Seventeen of 31 (54.8%) had a surgical kidney removal. Overall, 11 underwent 3D-assisted surgeries and 20 underwent routine ones. A significant higher success rate of partial nephrectomy (PN) was noted in the 3D group (72.7% vs. 30.0%). Patients in the 3D group presented a lower reduction in renal function but experienced a longer operation time, a greater estimated blood loss, and a higher postoperative morbidity. Subgroup analysis was conducted between patients undergoing PN with or without 3D assistance. Despite no significant difference, patients with 3D-assisted PN had a slightly larger tumor size and higher nephrectomy score, possibly contributing to a relatively higher rate of complications. However, 3D-assisted PN lead to a shorter warm ischemia time and a lower renal function loss without significant difference. Another subgroup analysis between patients under 3D-assisted PN or 3D-assisted RN showed no statistically significant difference. However, the nearness of tumor to the second branch of renal artery was relatively shorter in 3D-assisted PN subgroup than that in 3D-assisted RN subgroup, and the difference between them was close to significant.

Conclusions

3D visualized and printed kidney models appear to be additional tools to assist operational management and avoid a high rate of kidney removal for giant sporadic RAMLs.

Renal Angiomyolipoma Mimicking a Well-Differentiated Retroperitoneal Liposarcoma

A 37-year-old Burmese woman presented with an incidentally found retroperitoneal fat-containing tumor. The tumor was 9 cm in the longest diameter, surrounding the right kidney, and composed of homogenous adipose tissue with thickened septum-like structures and spotty nonadipose structures, which were enhanced on contrast-enhanced computed tomography and magnetic resonance imaging. The tumor did not show either a beak sign or synchronous angiomyolipoma-like lesion in the kidneys. The tumor had irregular septa, thin blood vessels, and spotty small soft-tissue nodules. The tumor did not contain any heterogeneously enhanced solid lesions suspicious for dedifferentiated liposarcomas. Based on these imaging findings, a clinical diagnosis of a well-differentiated liposarcoma was made. Under the consensus of a multidisciplinary cancer board, she was recommended to undergo core-needle biopsy to confirm the clinical diagnosis. However, she declined to undergo biopsy for financial reasons. She underwent kidney-sparing retroperitoneal tumor resection. Histopathologically, the tumor was an angiomyolipoma with positive immunostaining for HMB45 and Melan A. The present case suggests the importance of core-needle biopsy prior to surgical intervention for retroperitoneal fat-containing tumors.

Sporadic giant renal angiomyolipoma: A case report and literature review of clinical presentation, diagnosis, and treatment options

Giant angiomyolipoma (AML) is uncommon benign renal neoplasm that occurs sporadic or in association with tuberous sclerosis syndrome. There is no specific cutoff tumor size and/or weight to define giant AMLs. Ovarian stimulation hormones might cause a marked increase in its size and subsequent bleeding risk. Incidental findings are not common in those patients as mass-associated symptoms always present. Computed tomography scan is the standard diagnostic imaging study except for tumors with poor fat content. According to the clinical presentation, site and side of renal involvement giant sporadic AMLs have different treatment options, for example, active surveillance, selective renal artery embolization, nephron-sparing surgery, and/or radical nephrectomy. In the present case report, we present a 22-year-old female with huge right renal mass (29 cm × 23 cm × 21 cm) and treated with right radical nephrectomy which proved to be renal AML on pathology examination.

Renal angiomyolipoma

INTRODUCTION

Angiomyolipoma is one of the most common benign solid renal tumors. We investigated the characteristics of renal angiomyolipomas and the clinical outcomes of patients in the last thirteen years.

METHODS

The medical records of the patients who underwent nephrectomy were reviewed retrospectively from July 2005 to May 2018. The laboratory data, radiology, and pathology reports were recorded. Patients diagnosed with angiomyolipoma were included in the study.

RESULTS

A total of 28 patients were included in the study, eight of them male. The mean age of the patients was 55.89+14.49 years. The patients were treated with open and laparoscopic techniques. Partial nephrectomy was performed in 12 patients(42.85%). After pathological examination, 23 patients were diagnosed as fat rich, four patients as fat poor, and one as epithelioid angiomyolipoma. There were no recurrences in the follow-up 91.21+48.31 months.

CONCLUSION

Angiomyolipoma is a rare renal tumor in daily urology practice. Clinicians must be aware of its complications and manage patients well.