Laparoscopic two-step abdomino-parasacral resection of a giant pelvic lipoma: a case report

Introduction

Background

Lipomas are a common type of benign soft tissue tumors that can occur in every body region where adipose tissue is present, mainly the shoulders, back, neck, breast, abdominal wall, and proximal extremities (1).

Lipomas of the pelvic cavity are rare, and their surgical management is often challenging, mainly due to the considerable dimensions they can reach and the vital structures they can be adherent to.

Rationale and knowledge gap

Currently, only one study reported a similar case of a lipoma occupying the lesser pelvis treated with an asynchronous abdomino-parasacral approach, even though the procedure was open and not minimally invasive (2).

Objective

The present study reports a case of a giant lipoma of the right rectopelvic space and sciatic notch that was completely resected under a combined asynchronous laparoscopic abdominal and parasacral approach. We present this case in accordance with the CARE reporting checklist (available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-29/rc).

Case presentation

Medical history and diagnostic work-up

In October 2023, a 74-year-old female presented to the outpatient clinic of the Department of Colorectal Surgery of the Second Affiliated Hospital Zhejiang University (Hangzhou, China) complaining of abdominal distension and difficulty in defecation for over 6 months. She denied any rectal bleeding, abdominal pain, or significant unintentional weight loss. Routine blood tests were normal.

The patient reported a longstanding history of hypertension treated with one tablet of valsartan orally once daily, with adequate blood pressure control. There was no reported history of previous surgeries, drug or food allergies, and no family history of hereditary tumors.

Physical examination: abdomen revealed no tenderness or rebound tenderness, and no palpable masses were appreciated. Digital rectal examination revealed a palpable soft mass on the right wall of the rectum, with no bleeding observed from the anal canal.

The patient underwent contrast-enhanced computed tomography (CT) scan of the entire abdomen and pelvic magnetic resonance imaging (MRI).

Imaging findings: contrast-enhanced abdomen CT scan and pelvic MRI revealed the presence of a massive pelvic tumor located in the right rectopelvic space and sciatic notch, with an iso-intensity equivalent to that of fat tissue, suggestive of a lipomatous lesion, measuring 8.25 cm × 8.4 cm × 15.61 cm (Figures 1,2). A multidisciplinary discussion recommended surgical removal of the tumor.

Figure 1 Transverse CT scan of giant pelvic tumor (tumor size with 82.5 mm in width, black arrow). CT, computed tomography.

Figure 2 Sagittal T1-weighted MRI section (tumor size with 84 mm in minor axis and 156.1 mm in major axis, blue arrow). MRI, magnetic resonance imaging.

Surgical procedure

The surgical procedure was divided into two steps. In the first step, an abdominal laparoscopic approach was performed to expose the pelvic portion of the tumor and to dissect it from the surrounding pelvic tissues.

Patient was placed with modified lithotomy position. The upper limb was adducted. After the start of operation, the feet were raised 30 degrees and tilted to the right 15 degrees, so the head was lower than the rest of the body. The surgeon standed on the patient’s right side and to the right of the camera operator, while the assistant was on the opposite side.

The 10 mm trocar was placed in the upper umbilical edge as the observation port. A 12 mm working port was inserted in the right lower quadrant and a 5 mm port in the right midclavicular line parallel to umbilicus. Two 5 mm working ports were also inserted on the opposite side. During the initial laparoscopic exploration, it was noted that the giant pelvic mass occupied the space within the rectum and mesorectum, exhibiting close adherence to the rectal wall. Furthermore, the mass was in close proximity to vascular structures, including the inferior mesenteric vessels and the iliac tract. This intricate anatomical position necessitated careful manipulation during dissection to ensure complete removal of the mass with minimal injury to surrounding structures. Upon reaching the plane of the levator ani muscle during the laparoscopic dissection by HARMONIC ACE™, a continuous suturing technique was employed to close the pelvic peritoneum. Subsequently, the laparoscope was removed, and the trocar sites sutured (Figure 3).

Figure 3 Surgical procedure step by step for the operation. (A) Giant tumor in the pelvic (black arrow); (B) open the right-side mesentery of sigmoid colon; (C) open the peritoneal reflex; (D) separate right ureter (black arrow) from tumor; (E) the endpoint of the laparoscopic part; (F) continuous sutures close the pelvic entrance; (G) laparoscopic view of the pelvic after first part of the operation; (H) an incision was made in the midline posteriorly (curving towards the right side of the anus); (I) remove of the coccyx and the 5^th sacrum; (J) tumor dissection from parasacral approach; (K) the tumor was removed (black arrow indicating the posterior wall of the rectum); (L) the end of the operation (incision was sutured).

The patient was then repositioned into prone jackknife position. After adequate exposure of the patient’s buttocks using adhesive drapes, the second parasacral phase was initiated. A 16 cm incision was made in the midline posteriorly (curving towards the right side of the anus), cutting through the skin, dermis, and subcutaneous adipose tissue until exposing the sacrum and coccyx. The coccyx and the 5^th sacral bone were excised to adequately expose the surgical field. The tumor was carefully separated from adherent surrounding tissues by electric scalpel. Invasion of the tumor into the right levator ani muscle was observed. Consequently, the right levator ani muscle was partially excised along with the tumor, while the left levator ani muscle showed no apparent involvement. Following the complete removal of the tumor, the surgical area was irrigated, and hemostasis was ensured thoroughly. Throughout the surgical procedure, meticulous assessment of intraoperative blood loss was conducted. Blood losses were promptly managed through laparoscopic hemostatic techniques, thereby minimizing the risk of complications and ensuring a safe and effective surgical procedure.

Pelvic closure was performed in layers using 3-0 absorbable sutures, and the incision was closed with 1-0 absorbable sutures. One pelvic drainage tube was placed.

Pain management was effectively controlled through a multimodal pain management protocol, encompassing opioid and non-opioid analgesics.

The postoperative course was uneventful, and the patient was discharged on 10^th postoperative day.

Pathological result

• General inspection: a specimen of gray-yellow tumor tissue, measuring 16 by 11 by 4 cm, exhibits a gray-yellow greasy appearance upon sectioning, with a local fish-like texture and a partially intact capsule. Within, there is upper bone tissue measuring 3.5 by 3 by 1.5 cm, showing no evidence of macroscopic infiltration (Figures 4,5 ).
  

  Figure 4 Gross appearance of the tumor after excision. The size of the specimen was 19 cm in length, 14 cm in width. (A) The front side of the tumor; (B) the back side of the tumor with right levator ani muscle (black arrow), coccyx, and 5^th sacral bone (white arrow).
  

  Figure 5 General inspection of the giant lipoma.
• Histopathology: well-differentiated adipocytes composed of mature adipose tissue proliferate, and the fibrous septum is divided into lobules of different sizes, but there is no clear cytological dysplasia (Figure 6).
  

  Figure 6 Well-differentiated adipocytes composed of mature adipose tissue proliferate, and the fibrous septum is divided into lobules of different sizes by the method of H&E staining. H&E, hematoxylin and eosin.
• Molecular pathology: C10-04 (wax block): MDM2 gene amplification test [fluorescent in situ hybridization (FISH) method] MDM2 gene amplification was negative. A16-02 (wax block): MDM2 gene amplification test (FISH method) MDM2 gene amplification was negative, CDK4/SE12 gene amplification test (FISH method) CDK4 gene amplification was negative (Figure 7).
  

  Figure 7 FISH for CDK4 and MDM2 in the tumor. (A) CDK4 gene amplification was negative (FISH method, 1,000×); (B) MDM2 gene amplification was negative (FISH method, 1,000×). FISH, fluorescent in situ hybridization.
• Immunohistochemistry: C10-04 (wax mass): CD117 (−), DOG1 (−), CD34 (+), PDGFR alpha (−), α-SMA (−), desmin (partially +), β-catenin (−), S100 (+), SOX10 (−), EMA (−), STAT6 (-), Ki-67 (<1% +), MDM2 (partially weak +), CDK4 (partially weak +), HMB45 (−), RB1 (present).

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Lipoma is a commonly benign mesenchymal tumor that can develop in any part of the body containing adipose tissue. In contrast, deep located lipomas are rare and must be distinguished from well-differentiated liposarcomas for specific treatment and follow-up (1).

Due to their location and slow growth, pelvic lipomas are often asymptomatic for a prolonged time. Thus, on diagnosis, they are usually found to be of considerable size (2,3). The goal-treatment of these giant lipomas is radical resection.

Given the size of the tumor which occupied most of the pelvis and the close proximity to the right ureter, it was essential to access the pelvis via retroperitoneal approach.

To the best of our knowledge, only one case is reported in the scientific literature (2), according to a search performed in both the PubMed and Google Scholar databases, using ‘parasacral lipoma’, ‘abdomino-parasacral approach’ as key words.

In Sato et al.’s paper, the tumor was a lobulated mass of adipose tissue measuring 21 cm × 17 cm × 3 cm in size, 860 g in weight (2); otherwise, in our case report, it was 16 cm × 11 cm × 4 cm in size.

Giant retroperitoneal lipomas were treated with different approaches, which included an open surgical procedure, transgluteal and para-sacra approaches. Laparoscopy is often the first choice with respect to addressing any pelvic mass. Combined and asynchronous approaches are also described (3). Recently, it has been reported that robot-assisted surgery for pelvic lipoma is also feasible (4-6).

Although not delineated in the literature, it is noteworthy to mention that the robotic approach could have offered substantial advantages in this scenario. Robotic surgery confers enhanced precision, superior three-dimensional visualization, and increased maneuverability of surgical instruments, facilitating more precise and comprehensive excision of the giant pelvic mass. Additionally, the utilization of robotics could have further mitigated the risk of injury to surrounding structures and improved overall postoperative outcomes for the patient (4-6).

An abdomino-parasacral approach in which the position of the patient is changed from lithotomy to jack-knife has been performed (6-9).

In our experience, a two-step abdomino-parasacral approach provides more flexibility, but also a safe and easier dissection in this inaccessible area. As Sato et al. showed in their manuscript, the adoption of this approach helps to magnify the surgical exposure, allow a wide resection and reduce the stress related to the surgeon’s fatigue (2). Therefore, Wanebo et al. also agrees with the two-step abdomino-parasacral approach. In fact, it can allow protection for rectum, ureters, and major blood vessels (10). Previous authors have focused on several methods for preserving function by sparing specific nerve roots (11-13).

It is imperative to highlight that the patient experienced an uncomplicated recovery, with rapid improvement of preoperative symptoms and significant reduction in abdominal distension and defecation difficulty.

Therefore, the present report describes the second case of parasacral giant lipoma removal with a two-step abdomino-parasacral resection to raise awareness among physicians and surgeons regarding the importance of a correct clinical evaluation, diagnostic workup and surgical wide resection, nerve and major vessels-sparing and without complications.

Conclusions

A two-step abdomino-parasacral resection of the lipomatous tumor was advantageous to manage en bloc resection of a giant pelvic lipoma in our case report.

Acknowledgments

Funding: This work was supported by the National Natural Science Foundation of China (No. 82172851).

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-29/rc

Peer Review File: Available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-29/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jgo.amegroups.com/article/view/10.21037/jgo-24-29/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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