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Show Visual Field Improvement After Pituitary Tumor Surgery in Patients With McCune-Albright Syndrome Jin Ma, MD, Chan Zhao, MD, Renzhi Wang, MD, Feng Feng, MD, Erqian Wang, MD, Hui You, MD, Ying Jiang, MD, Meifen Zhang, MD, Yong Zhong, MD Background: McCune-Albright syndrome (MAS) is a rare, spo-radic congenital disorder, in which optic neuropathy may cause devastating visual consequences. Pituitary adenoma with over-production of growth hormone (GH) is present in approximately two-thirds of MAS patients, and its role in the pathogenesis of MAS-associated optic neuropathy has not been studied. Methods: Three MAS patients with GH-secreting pituitary adenoma and optic chiasm compression diagnosed between January 2008 and November 2010 were included in this case series. Transsphenoidal pituitary resection was performed in all 3 patients. Neuro-ophthalmologic evaluation was per-formed at presentation and every 6 months during follow-up. Results: Of the 3 patients, 2 were female and 1 was male; their ages ranged from 17 to 27 years. Visual acuity ranged from 20/20 to 20/200 before surgery and all had visual field loss. The patients were followed up for 6-18 months with substantial improvement in their visual fields. Conclusions: GH-secreting pituitary adenoma may contrib-ute to optic nerve damage, at least partially, in MAS patients. Pituitary surgery may be important for visual recovery in some MAS patients in whom there is compres-sion of the optic chiasm. Journal of Neuro-Ophthalmology 2013;33:26-29 doi: 10.1097/WNO.0b013e3182726b69 © 2012 by North American Neuro-Ophthalmology Society McCune-Albright syndrome (MAS), characterized by a clinical triad of café-au-lait skin pigmentation, polyostotic fibrous dysplasia (FD), and single or multiple endocrinopathies, is a rare and sporadic congenital disor-der first reported by McCune and Albright separately in the 1930s (1,2). Craniofacial involvement of FD may cause acute or chronic vision loss (3,4). Although progres-sive optic canal narrowing has long been believed to be the leading cause of optic neuropathy in FD/MAS patients (5-7), large case series have failed to document an age-related progression of optic canal narrowing or a causal relationship between optic canal narrowing and optic neu-ropathy (8,9). Rather, growth hormone (GH) excess has been associated with optic neuropathy and optic nerve stretching from bone expansion postulated to be the mech-anism of vision loss (8,9). Pituitary tumor can be detected in about two-thirds of MAS patients with GH excess (10). In this report, improve-ment of visual field (VF) was observed after transsphenoidal surgery in 3 MAS patients with GH-secreting pituitary ade-noma and optic chiasm compression, providing evidence that pituitary tumor may contribute to vision loss, at least partially, in some MAS patients. METHODS Three newly diagnosed MAS patients with pituitary tumor at Peking Union Medical College Hospital between January 2008 and November 2010 were included. Our study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of Peking Union Medical College Hospital. Informed con-sent was obtained from each patient before any examina-tion or treatment. Each patient was evaluated by specialists in ophthalmology, endocrinology, neurosurgery, plastic surgery, and otolaryngology and underwent thin-section computed tomography (CT) of the craniofacial structures and magnetic resonance imaging (MRI) of the brain. MAS was diagnosed based on the presence of at least 2 elements of the clinical triad (11). All 3 patients underwent navi-gation- assisted transsphenoidal tumor resection. Departments of Ophthalmology (JM, CZ, EW, MZ, YZ), Neurosurgery (RW), Radiology (FF, HY), and Pathology (YJ), Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China. The authors report no financial or conflicts of interest. J. Ma and C. Zhao contributed equally to this work and both qualify as the first author. Address correspondence to Yong Zhong, MD, Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 1 Shuai Fu Yuan, Dongcheng District, Beijing 100730, China; E-mail: yzhong_eye@yahoo.com.cn 26 Ma et al: J Neuro-Ophthalmol 2013; 33: 26-29 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Neuro-ophthalmologic examination included best-corrected visual acuity, color vision (Ishihara pseudoiso-chromatic plates), pupillary and VF testing, and fundu-scopy. VFs were performed using the Octopus 101 perimeter (Haag-Streit, Inc, Koeniz, Switzerland) tG2 program with Tendency Oriented Perimetry strategy. Eyes with very poor vision were tested with tG2 program, LVC (central low vision test) program with LVS (low vision Goldmann V) strategy. Color vision was tested with 14 Ishihara color plates in bright diffused light; abnormal color vision was defined as failing to identify 10 or more plates. Neuro-ophthalmologic re-evaluations were performed every 6 months during follow-up. RESULTS Ages of patients were 17, 21, and 27 years with 2 females and one male. Visual acuity ranged from 20/20 to 20/200, with some impairment of color vision, and all had optic disc pallor. Preoperative VFs are shown in Figure 1 (top panel). All 3 patients had typical café-au-lait skin pigmenta-tion, craniofacial polyostotic FD with bilateral optic canal narrowing (Fig. 2), GH excess with acromegaly (patient 1 had concurrent prolactin excess), and pituitary macroadenoma with compression of the optic chiasm (Fig. 3). All patients underwent transsphenoidal resection, and none had excision or shaving of the osseous lesions or optic canal decompression. Patients 1 and 2 were given intrave-nous bisphosphonate. Magnetic resonance imaging of the brain in all 3 patients performed 4 to 12 months after the surgery showed successful removal of the pituitary tumor and decompression of the optic chiasm. The patients were followed for 6-18 months after surgery with substantial improvements in VF results (Fig. 1, bottom panel). No improvement was detected in visual acuity, color vision, pupillary testing, or funduscopy. Immunohistochemistry of the surgically removed bone and pituitary tumor FIG. 1. Automated visual fields done with Octopus perimeter. Top panel, before surgery; bottom panel, after surgery. FIG. 2. Patient 2: Computed tomography of right optic canal (arrow) in axial (A), sagittal (B), and oblique (C) projections. The optic canal is narrowed with marked thickening and deformity of the craniofacial bones. Ma et al: J Neuro-Ophthalmol 2013; 33: 26-29 27 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. confirmed the diagnosis of FD (Fig. 4) and GH-secreting pituitary adenoma (Fig. 5). DISCUSSION Both MAS and isolated FD are sporadic noninherited genetic disorders caused by postzygotic mutations of GNAS1 gene encoding a subunit of stimulatory G protein (12,13). The phenotype from postzygotic single-cell GNAS1 mutation is variable, ranging from a constellation of multisystemic abnormalities to single or multiple FD lesions confined to the skeleton system (14-16). Whether the disease is generalized or localized depends on when the mutation occurs during embryogenesis (12). Both acute and chronic visual impairment have been well documented in the literature in FD/MAS patients. Michael et al (3) noted that most reported cases of vision loss in FD are because of mass lesions, including cystic FD, mucocele, and aneurysmal bone cyst. Progressive optic canal narrowing has long been considered a major cause of chronic optic neuropathy in craniofacial FD/MAS patients. This has led to prophylactic optic canal decompression (6,7). However, in a large cross-sectional analysis of a case-control cohort, Lee et al (8) showed that narrowing of the optic canal in craniofacial FD was not associated with visual loss. In this study, the majority of patients did not develop optic neu-ropathy even with severely narrowed optic canals. In addition, reports (9,10) of both prophylactic and inter-ventional optic canal decompression with long-term fol-low- up do not demonstrate efficacy of this surgical procedure. Currently, optic canal decompression is only recommended for FD patients with acute or progressive visual impairment (3,9,17). FD/MAS patients were not screened for pituitary tumor in previous studies. However, in our patients, the results of VF testing and neuroimaging indicated optic chiasm compression, and they all underwent transsphenoidal tumor resection with improvement of VFs. We conclude that chiasmal compression was a contributing factor to visual impairment. In addition, pituitary adenoma also might explain the association of GH excess documented in previous studies of patients with MAS (9,14). FIG. 3. Contrast-enhanced T1 coronal magnetic resonance imaging reveals pituitary tumor with optic chiasm compression. FIG. 4. Patient 3: Fibrous dysplasia. Bone from skull base shows irregularly shaped trabeculae of woven bone in a background of moderately cellular fibrous connective tis-sue (hematoxylin and eosin, ·150). FIG. 5. Pituitary adenoma comprised of sheets of anterior pituitary cells arranged in cords or nests in a pseudo-glandular pattern (hematoxylin and eosin, ·150). Inset: immunochemistry demonstrates strong intracytoplasmic staining (brown) of pituitary adenoma cells for growth hor-mone (diaminobenzidin, ·150). 28 Ma et al: J Neuro-Ophthalmol 2013; 33: 26-29 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. REFERENCES 1. McCune DJ. Osteitis fibrosa cystica: the case of a 9 year old girl who also exhibited precocious puberty, multiple pigmentation of the skin and hyperthyroidism. Am J Dis Child. 1936;52: 743-744. 2. Albright F, Butler AM, Hampton AO, Smith PH. 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Optic nerve compression in craniofacial fibrous dysplasia: the role and indications for decompression. Plast Reconstr Surg. 2007;120:1957-1962. Ma et al: J Neuro-Ophthalmol 2013; 33: 26-29 29 Original Contribution Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. |
