Laparoscopic partial adrenalectomy in patients with aldosterone-producing adenomas: indications, technique, and results

Material and methods 

In 13 selected patients with primary hyperaldosteronism caused by small, single aldosterone-producing adenomas, we performed partial adrenalectomies. All patients were referred to us for laparoscopic treatment from different endocrine departments, where the diagnosis was assessed by determination of the adrenal hormones in serum and urine, as well as by the determination of serum electrolytes. All patients had elevated aldosterone levels, and their potassium was less than the normal range. The average age of our 13 patients was 60 years (range 39 to 78), 5 were women and 8 men. The tumors were distributed more or less equally, 6 on the right and 7 on the left side. The average tumor size was 2 cm (range 1.5 to 2.5). To minimize the risk of a partial resection in a patient with an aldosterone-producing adrenocortical carcinoma, preoperative unenhanced and delayed-enhanced computed tomography (CT) scans were obligatory. The indication for partial adrenalectomy of the adrenal mass was based on the evidence of attenuation of 11 HU or less on the unenhanced CT scan and an attenuation of 37 HU or less on the delayed-enhanced CT scan 30 minutes after contrast administration. The exclusion criteria for partial adrenalectomy were a diameter greater than 3 cm and tumors located in a rather concentric position in the gland. Using these criteria, one can expect a sufficient amount of normal tissue after the resection. Furthermore, we excluded tumors directly attached to the adrenal vein to spare the vein and at least one of the three arteries.

For laparoscopic partial resection, we have always preferred a transperitoneal approach, as described previously for transperitoneal adrenalectomy by Rassweiler et al.8 and Peschel et al.9

It is important to expose the margins of the whole gland and the tumor completely before beginning the partial resection. To preserve the blood supply of the remnant adrenal gland, mobilization of the tumor within benign margins should be started at the side of the tumor. Furthermore, the unaffected portion of the gland should not be dissected.

The tumor resection itself was carried out with the endoshears after preliminary bipolar coagulation of the resection line at a distance of 2 or 3 mm from the tumor. The preliminary bipolar coagulation avoids arterial or venous bleeding. The pressure of the pneumoperitoneum largely prevents parenchymal bleeding. The resected tumor is put in an organ bag and parked in the abdomen. To avoid venous bleeding out of the adrenal myelon or parenchymal bleeding after releasing the pneumoperitoneum, we sealed the resection margins with 1 mL of fibrin glue. In the first 4 patients, a drain was left in place for 1 day; no drain was used in the remaining 9 patients. On the left side, the colonic flexure was replaced in position and fixed to the abdominal wall by one or two interrupted endo-sutures. The tumor was then retrieved from the abdomen within the organ bag by slightly widening one of the trocar incisions.

Results 

All laparoscopic partial adrenalectomies were finished successfully, and no conversion to open surgery was necessary. The mean operating time was 99 minutes (range 65 to 118), and the mean blood loss was 78 mL (range 0 to 215). The postoperative hospital stay ranged from 2 to 6 days (average 4.3).

No major complications occurred intraoperatively or postoperatively. One patient developed a subcutaneous hematoma from port site bleeding that required no further treatment and was considered a minor complication.

Patients started liquid oral intake on the day of operation, were mobilized on the next day, and were discharged on the second to sixth postoperative day.

As expected, the histologic workup showed an adenoma in all 13 patients, with negative surgical margins.

Enhanced CT scans were performed 3 months after surgery. These CT scans revealed a normal blood supply to the remaining healthy adrenal tissue. The serum aldosterone levels returned to normal, and the blood pressure readings were in the age-related normal ranges at follow-up. In all patients, the serum potassium level climbed to greater than 3.5 mmol/L and all 9 patients who required spironolactone or other antihypertensive drugs before surgery were able to refrain from this treatment. No local tumor recurrences were observed with a median follow-up of 39 months (range 3 to 82).

Comment 

Adrenalectomy was one of the first indications for which laparoscopy proved superior to open surgery in all aspects.3 Thus, it is not surprising that laparoscopic adrenalectomy has become the standard in adrenal tumor surgery. Because the vast majority of adrenal lesions are benign,1 adrenal-sparing surgery should be considered more often. Only a few studies have reported on open adrenal-sparing surgery, mainly in patients with imperative indications (solitary glands or bilateral tumors).9, 10 As far as we can see, three reasons for this are the most relevant. First, the adrenal glands are a pair of organs; second, from a technical point of view, adrenalectomy is easier to perform than partial adrenalectomy; and third, the histologic features of the tumor are unclear.

The simple fact of a second adrenal gland does not justify the removal of the afflicted gland in every case. Although no immediate hormonal consequences result after unilateral adrenalectomy, a small but distinct risk of losing the second adrenal gland later on for other reasons exists, which would require lifelong steroid replacement therapy with all its consequences to the patient.

Because the adrenal gland is a small organ, adrenal-sparing surgery is more difficult than organ removal in open surgery. In particular, parenchymal bleeding and bleeding out of the myelon are much feared complications and difficult to handle with suturing techniques.

Because of its magnification, laparoscopy offers a much more precise dissection than open surgery.11 The tumor borders can be easily identified and the resection lines outlined exactly in the unaffected parenchyma with a safety margin of about 2 to 3 mm. The preliminary bipolar coagulation along the outlined resection line avoids major bleeding during the resection of the tumor. The pressure of the pneumoperitoneum largely prevents parenchymal bleeding and bleeding out of the myelon.4, 12 Thus, when the laparoscopic partial adrenalectomy is finished, a nearly dry resection line on the remaining healthy gland should be observed. At that time, this resection line can be easily sealed with fibrin glue, because bleeding will not wash the glue away. The glue is fixed within a few minutes and prevents parenchymal bleeding and bleeding from the myelon after releasing the pneumoperitoneum.

We strictly avoided the use of vascular staplers for partial resection, as described by other investigators13 in this indication to achieve hemostasis. Because these staplers allow only a straight cut and have a diameter of 7 mm, we might risk losing an unnecessary amount of normal tissue using this technique. Cutting along the tumor with a small margin of normal tissue spares a maximum of the healthy remnant gland and, in combination with the above-mentioned technique of tissue gluing, does not compromise hemostasis. Furthermore, published reports support the preservation of the adrenal vein to maintain the function of the remnant adrenal gland.14 We agree with these findings, and they support our delicate resection technique with minimal mobilization only in the tumor-bearing area to maintain an optimal blood supply for the remnant gland. This is the reason we excluded patients with a central lesion from partial adrenalectomy. The value of this particular point of technique has been stressed by our postoperative enhanced CT findings of a good arterial blood supply in the remaining adrenal gland.

The unclear histologic features of the tumor are a major argument against partial resection. The reason for Conn’s syndrome is an aldosterone-producing adenoma in about 75% of cases. In the remaining 25%, bilateral adrenocortical hyperplasia is responsible for primary hyperaldosteronism.1 These adenomas, with a mean diameter of less than 2 cm, are relatively small at the time of detection.2 Adrenocortical carcinomas are extremely rare malignancies and only one half of them are hormonally active. They mainly produce corticosteroids; in rare cases, virilization occurs. Conn’s syndrome due to adrenocortical carcinoma is an extremely uncommon event.15 To be absolutely sure that we perform our partial resections only on patients with benign lesions, we obtain CT scans. Imaging studies showed that lesions having 11 HU or less on unenhanced CT scans are always adenomas.16, 17 In lesions with more than 11 HU, we obtain delayed-enhanced CT scans. With this investigation, adrenal adenomas exhibit a greater washout of contrast material than do adrenal lesions that are not adenomas.18, 19 Therefore, such lesions have significantly higher attenuation than adenomas on delayed-enhanced CT scans obtained 30 minutes after administration of contrast material. The specificity of this investigation at a cutoff of 37 HU after 30 minutes is 100%.20 Following the above-mentioned preoperative investigational program one can be sure the lesion is benign in patients with adrenal tumor-induced hyperaldosteronism.

The significance of the CT scans done 3 months postoperatively should also be discussed. The primary aim of this investigation was to determine whether any hematomas were present from delayed parenchymal bleeding owing to insufficient hemostasis. No hematomas could be detected on the CT scans, but the remnant adrenal tissue, taking up contrast medium, was easily seen in every case. We considered this a sign of a good blood supply. Nevertheless, we realize this information is weak evidence of functioning adrenal tissue. For functional testing, nuclear scintigraphic investigations such as the J 131-cholesterol scintigram would have been best. Because of economic reasons, we did not perform additional investigations and concluded that the remnant tissue was functioning normally from the evidence of a good blood supply.

Conclusions 

Laparoscopic partial adrenalectomy is a safe, effective, and minimally invasive therapeutic option for patients with adenomas causing primary hyperaldosteronism. The crucial advantage to adrenalectomy is keeping functional tissue on the side with the tumor in case of a subsequent adrenalectomy on the contralateral side for other reasons. On the basis of our experience, we recommend it for patients with Conn’s syndrome who have small tumors identified as adenomas on delayed-enhanced CT scans. The tumor should involve only a certain part of the gland, so that adequate remaining normal tissue can be expected, and stapling techniques should be avoided to preserve as much of the gland as possible.