Aldosteronoma

The most common cause of hyperaldosteronism is an aldosterone-producing adenoma. Aldosteromas are rarely bilateral. Other causes of hyperaldosteronism include hyper-plasia and, very rarely, carcinoma. Total adrenalectomy is the standard of care for unilateral adenomas, because the function is preserved by contralateral adrenal hypertrophy. Partial adrenalectomy was initially proposed for bilateral aldosteroma. Nakada et al. (14) compared the functional outcome of open unilateral partial versus total adrenalectomy in 48 patients. Despite adequate hormone levels and the lack of replacement therapy, patients who underwent unilateral total adrenalectomy demonstrated suboptimal response to stress. Conversely, patients undergoing tumor enucle-ation (partial adrenalectomy) had better functional reserve. Further, there were no tumor recurrences in either group over a mean follow-up of five years. As a result, indications for adrenal-sparing surgery have been expanded by select groups to include unilateral aldosteromas. Estimated incidence of malignancy in adrenal lesions smaller

The main adrenal vein may be sacrificed if needed, although every effort to preserve it should be made.

The least controversial indication for partial adrenalectomy is hereditary pheochromocytoma.

than 6 cm in diameter is low—1 in 10,000 (15-17). However, micro- or macronodularity in an adjacent area of the gland is present in 7% to 38% of aldosteromas, a circumstance that is a clear contraindication for partial adrenalectomy (18).

Cushing's Syndrome

The major cause of Cushing's syndrome is adrenal hyperplasia. A small percentage of patients with Cushing's syndrome have a radiologically well-defined adenoma amenable to partial adrenalectomy. Cushing's adenomas are usually larger in size (several centimeters) than aldosteromas, and the adjacent adrenal parenchyma and the contralateral adrenal gland are often atrophic. laparoscopic partial adrenalectomy is technically more challenging in such cases. Because of this, the remnant adrenal recovers slowly, with the need for temporary steroid substitution.

Pheochromocytoma

The least controversial indication for partial adrenalectomy is hereditary pheochromocytoma.

Pheochromocytoma is inherited in an autosomal dominant pattern and can be occasionally associated with different syndromes, including von Hippel-Lindau disease, multiple endocrine neoplasia type 2 (multiple endocrine neoplasia 2A/B), and neurofibromatosis type 1. In this specific subset of patients, an increased incidence of multifocal tumors, risk of delayed relapse over the long term, and detection of asymptomatic tumors on screening patients with known syndrome or relatives of a proband patient are not infrequent. Bilateral total adrenalectomy followed by hormonal replacement has been the standard treatment so far. Patients with hereditary unilateral or bilateral pheochromocytomas are candidates for partial adrenalectomy because of a definite risk of contralateral metachronous tumors formation. In this specific setting, open partial adrenalectomy has achieved encouraging results (19-23). The major drawback of partial adrenalectomy is the risk of recurrent tumors in the adrenal remnant due to medullary cells inevitably remaining within the spared cortex. Such tumor recurrence is, in fact, due to genetic predisposition rather than residual tumor from incomplete resection (Fig. 1). Hence, it is essential to weigh the benefits of adrenal function preservation against the risk tumor reoccurrence. The risk of reoccurrence after open partial resection for pheochromocytoma in patients with von Hippel-Lindau has been assessed in two large series. Walther et al. reported recurrent tumor in 1 of 13 patients after a median follow-up of 18 months (20). Neumann et al. noted one ipsilateral recurrence out of 29 patients undergoing partial adrenalectomy at a mean follow-up of six years (19). Patients with multiple endocrine neoplasia 2 have a 0% to 33% risk of developing

FIGURE 1 ■ Recurrent right pheochromocytoma after dissection. Note the clear distinction between tumor-containing adrenal gland and normal adrenal gland, and the adrenal vein could be spared after ligating the small venous tributary draining the tumor. Abbreviations: L, liver; TU, tumor mass; AG, normal adrenal gland; AV, adrenal vein; VC,vena cava.

FIGURE 1 ■ Recurrent right pheochromocytoma after dissection. Note the clear distinction between tumor-containing adrenal gland and normal adrenal gland, and the adrenal vein could be spared after ligating the small venous tributary draining the tumor. Abbreviations: L, liver; TU, tumor mass; AG, normal adrenal gland; AV, adrenal vein; VC,vena cava.

recurrence over a median follow-up of 54 to 88 months (22,23). Considering the available evidence, partial adrenalectomy appears to be well justified, given the rarity of malignant tumors in inherited pheochromocytoma (10). Subtotal adrenalectomy has been advocated (23-25), but this does not necessarily remove all medullary tissue and hence the risk of recurrence remains with the additional disadvantage of removing an excessive amount of cortical tissue, thus compromising the adrenal function.

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