Retroperitoneal Laparoscopic Liposuction for Large Adrenal Myelolipomas: A Report of Nine Cases

Abstract

Objective:

Removing relatively large adrenal myelolipomas using retroperitoneal laparoscopy is difficult and carries risk of intraoperative injury to adjacent organs and vessels. We aimed to introduce a new method of retroperitoneal laparoscopic liposuction with suction units for resection of large adrenal myelolipomas.

Patients and Methods:

From June 2005 to October 2011, 8 patients (nine lesions, including bilateral lesions in 1 patient) with adrenal myelolipoma more than 8 cm in maximum diameter underwent retroperitoneal laparoscopic liposuction with suction units. Patients included 3 males and 5 females with a mean age of 47 years (range, 35–62 years). Tumor resection was performed after deflation and shrinkage of tumor. The mean maximum diameter was 10.5 cm, ranging from 8 to 14 cm. Five tumors were located on the right side, two were on the left side, and one was bilateral. Adrenal computed tomography was done in each patient preoperatively. Round or oval masses were found in dense fat in the adrenal area, and all cases were diagnosed as adrenal myelolipoma. Five patients had backache or abdominal discomfort; three patients had no symptoms.

Results:

The mean operation time was 75 minutes, and the mean intraoperative blood loss was 30 mL. The mean postoperative length of stay was 3 days. No significant intraoperative or postoperative complications occurred. The follow-up length ranged from 8 to 77 months. No tumor recurrence was observed.

Conclusions:

Retroperitoneal laparoscopic liposuction with suction units is safe and effective for resection of relatively large adrenal myelolipomas. Deflation and shrinkage of the tumor make the operation safer and easier without affecting its pathological diagnosis.

Introduction

Adrenal myelolipoma is a relatively rare benign tumor occurring with a nonfunctional adrenal gland and is composed of mature adipose tissue and bone marrow hematopoietic tissue.¹ This tumor was first described by Gierke in 1905 and was named myelolipoma by Oberling in 1929.² However, the exact etiology of myelolipoma still remains unclear. In the past, this kind of tumor was most commonly found during autopsy. The incidence ranged from 0.08% to 0.4%. Recently, along with the extensive application of imaging examinations such as ultrasound, computed tomography (CT), and magnetic resonance imaging, more tumors without symptoms were discovered incidentally, and the number of myelolipoma patients has increased significantly, accounting for about 10%–15% of incidentally discovered asymptomatic renal tumors.³ Most myelolipomas are relatively small without symptoms. In patients with myelolipomas, the male to female ratio is about 1.75:1.0. At present, no definite rule has been applied to the surgical indication for adrenal myelolipoma. However, it is generally accepted that surgical treatment is not necessary for asymptomatic adrenal myelolipomas less than 4 cm in diameter, and only regular observation is needed. Relatively large lesions may compress adjacent tissues and organs to produce symptoms such as backache and abdominal discomfort and even may cause spontaneous rupture, resulting in retroperitoneal hemorrhage.⁴ The possibility of spontaneous rupture increases significantly in tumors more than 7 cm in diameter, for which surgical treatment is necessary.³

Between June 2005 and October 2011, 8 patients (nine lesions; 1 patient had bilateral lesions) with adrenal myelolipomas more than 8 cm in maximum diameter underwent retroperitoneal laparoscopic liposuction with suction units in our department. The tumors were removed after marked shrinkage, and the outcomes were excellent in all cases. Our objective in this study was to report the details of these 8 cases and introduce a new method for retroperitoneal laparoscopic liposuction with suction units.

Subjects and Methods

This was a prospective study. From June 2005 to October 2011, 8 patients (nine lesions, including bilateral lesions in 1 patient) with adrenal myelolipoma more than 8 cm in maximum diameter underwent retroperitoneal laparoscopic liposuction with suction units.

Ethical considerations

The study followed the principles of the Declaration of Helsinki. The internal review board of The Second Affiliated Hospital of Zhejiang University (Hangzhou, China) approved the protocol for the study. All participating patients provided signed informed consent.

Clinical data

Eight patients were included in the current study, including 3 males and 5 females. The mean age was 47 years, ranging from 35 to 62 years. The mean maximum diameter of the tumors was 10.5 cm, ranging from 8 to 14 cm. Five were located on the right side, two were on the left side, and one was bilateral. Adrenal CT was carried out for every patient before surgery. There were round or oval masses in dense fat in the adrenal area, and all cases were diagnosed as adrenal myelolipoma. Five patients had backache or abdominal discomfort, and the remaining 3 patients were without any symptoms. The mean CT value was about −75 Hounsfield units.

Surgical procedure

The patient was placed in the lateral position after general anesthesia with endotracheal intubation. A skin incision about 2 cm in length was made inferior to the 12th rib on the posterior axillary line. Blunt dissection of the muscle layer and fascia lumbodorsalis was carried out to reach the retroperitoneal space. The retroperitoneal space was dissected, a balloon dilator was inserted, and 800 mL of air was injected to expand the retroperitoneal space. A 10-cm tube was inserted from 2 cm superior to the iliac crest on the midaxillary line under finger guidance. A 5-mm tube was inserted from the inferior costal margin on the anterior axillary line, and a 10-mm tube was inserted from the channel in the posterior axillary line. The incisions were closed. After the establishment of the artificial retroperitoneal cavity, it was filled with CO₂ gas to maintain a pressure of 12–15 mm Hg, which is the same as the intraoperative pressure. The laparoscope and related instruments were then placed in position.

The perirenal fascia was cut open longitudinally near the lateral margin of the psoas muscle to enter the loose interval between the surface of the psoas muscle and the adipose capsule of the kidney. This interval space was dissected sufficiently with an ultrasonic scalpel, and further dissection was carried out until the inferior site of the diaphragm was reached. The perirenal fat capsule on the upper pole of the kidney was cut open, and the upper part and medial margin of the tumor were dissected to expose the tumor within the adrenal gland. The texture of adrenal myelolipoma was as soft as the fat tissue. The membrane was thin and easily damaged during dissection. Tumor content was yellow and soft like jelly. An incision 1 cm in length was made on the membrane surface to put in a suction device. Most of the tumor content was sucked out under routine suction pressure (0.2–0.4 kPa). After marked shrinkage of the lesion, the suction device was removed, and the membrane incision was closed with a titanium clip. Further dissection was carried out along the membrane, and en bloc tumor resection was performed. The specimen was put into a sterilized specimen bag and removed from the incision at the posterior axillary line.

Results

Patients' demographic and clinical data are shown in Table 1. The mean operation time was 75 minutes, and the mean intraoperative blood loss was 30 mL. The mean postoperative length of stay was 3 days. No significant intraoperative or postoperative complications occurred in any patient. The results of postoperative pathological examination confirmed that all cases were adrenal myelolipoma. Staged surgeries were performed for the 1 patient who had bilateral adrenal myelolipomas. The follow-up duration for all cases ranged from 8 to 77 months. Regular ultrasound and CT examinations were carried out during follow-up visits, and no tumor recurrence was observed in any of the 8 patients.

Table 1.

Clinical Data

Patient code	Sex	Age (years)	Site	Maximum diameter of the tumor (cm)	Operative time (minutes)	Postoperative length of stay (days)	Follow-up duration (months)
1	Female	47	Right	8	78	3	36
2	Female	52	Right	12.5	68	2	28
3	Female	38	Left	14	82	2	77
4	Male	48	Right	11	65	4	8
5	Female	62	Bilateral	Left 8 Right 8.5	Left 77 Right 82	Both: 3	Left 35 Right 38
6	Male	58	Left	11.5	68	3	18
7	Male	35	Right	8.5	72	4	46
8	Female	36	Right	12.5	83	3	23

Discussion

Laparoscopic surgery is the gold standard for the treatment of adrenal diseases.⁵ Two approaches are applied: one is the transperitoneal approach, and the other is the retroperitoneal approach. The retroperitoneal approach can achieve direct exposure, its anatomical relationship is simple, organs in the abdominal cavity are unlikely to be damaged, and intestinal adhesions can be avoided. Urologists are familiar with retroperitoneal anatomy and are willing to choose the retroperitoneal approach. However, the retroperitoneal space is narrow, and this may increase the difficulty of surgical manipulation, especially for tumors with relatively large volumes. An adrenal myelolipoma is often located on the right side, and when the maximum diameter of the tumor is more than 8 cm, it occupies the whole adrenal area with almost no space between it and the peripheral organs or the peritoneum, making surgical exposure exceptionally difficult. For an adrenal myelolipoma located on the right side, exposure of the inferior vena cava is particularly difficult. Dissection between the inferior vena cava and the tumor may easily damage the inferior vena cava, resulting in massive bleeding. For an adrenal myelolipoma located on the left side, the tail of the pancreas is likely to be injured, and it may cause pancreatic leakage. Moreover, because the membrane of adrenal myelolipoma is thin and the lesion is soft, it may be ruptured easily during dissection, and en bloc tumor resection is difficult.

During previous operations, we found that the texture of the lesion was like a soft jelly, and the broken fragments of the lesion could be sucked out easily with suction devices. Therefore, we made a small incision on the tumor membrane and put in a suction device, which easily sucked out the contents within the tumor under routine suction pressure (0.2–0.4 kPa) without significant bleeding. After removal of most of the tumor, the lesion became small, and the interval between the tumor and the peripheral tissue widened, allowing the inferior vena cava to be easily exposed. En bloc resection of the tumor could be carried out easily along the tumor membrane, making surgery easy and safe. The mean operation time was 75 minutes, which is similar to that of small adrenal tumor surgeries. In addition, because most parts of the tumor were already removed, the left lesion and membrane could be taken out easily from the incision inferior to the 12th rib without extending the incision. Because injury was minimal, postoperative recovery was quick, and the mean postoperative length of stay was only 3 days.

Because adrenal myelolipoma is a benign lesion, small adrenal myelolipomas usually have no symptoms, and no treatment is needed. Therefore, most cases requiring surgical treatment have relatively large tumors. Moreover, because adrenal myelolipoma has characteristic changes in imaging examinations, including varied hyperechoes in the ultrasound and negative CT values,⁶ preoperative diagnosis is relatively definite. Hence, malignant tumors are less likely to be misdiagnosed as myelolipoma, and the possibility of tumor spread during liposuction is also less likely to occur. Additionally, because all contents removed by suction were sent for pathological testing, we believe that this kind of procedure does not affect the final pathological diagnosis. However, in clinical practice, it is sometimes difficult to differentiate myelolipoma from atypical renal hamartoma. When renal hamartoma mainly grows outwardly, it is easily misdiagnosed as adrenal myelolipoma because a mass with negative CT values is found at the renal area. While the boundary between adrenal myelolipoma and the kidney is typically clear, tumor extension into the kidney can be observed in some CT sections of renal hamartoma. Therefore, pathological tests in the present study showed that all cases were adrenal myelolipoma, and no recurrence was found in any of the 8 patients during 8–77 days of follow-up.

To our knowledge, there has been no previous report of retroperitoneal laparoscopic liposuction with suction units before tumor resection in the surgical treatment of relatively large adrenal myelolipoma. This method can decrease surgical difficulty greatly, can increase the surgical safety, and does not affect the postoperative pathological diagnosis. In conclusion, we suggest that retroperitoneal laparoscopic liposuction with suction units is safe and effective for resection of relatively large adrenal myelolipomas. Deflation and shrinkage of the tumor make the operation safer and easier without affecting its pathological diagnosis.

Footnotes

Disclosure Statement

No competing financial interests exist.

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