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Show Ectopic Pituitary Adenoma in the Spheno-Orbital Region Hao Wang, MD, Wenhua Yu, MD, Zuyong Zhang, MD, Wei Xu, MD, Fulin Zhang, MD, Weimin Bao, MD Abstract: Ectopic pituitary adenomas (EPAs) are rare tumors that most often occur in the sphenoid sinus or suprasellar region. We describe a 66-year-old man who presented with unilateral proptosis and an ipsilateral abduction deficit caused by an EPA in the spheno-orbital region. The tumor was completely excised with elimina-tion of proptosis and restoration of full ocular ductions. There were no complications. Diagnosis of a hormonally inactive EPA was reached on the basis of immunohisto-chemical studies of the operative specimen. This is the first documented case of an EPA in this location. It may have originated from Rathke pouch remnant cells in the lateral wall of the sphenoid sinus. Journal of Neuro-Ophthalmology 2010;30:135-137 doi: 10.1097/WNO.0b013e3181c5d1a2 2010 by North American Neuro-Ophthalmology Society First described by Erdheim (1) in 1909 as ‘‘a growth hormone-secreting tumor in the sphenoid sinus,'' ectopic pituitary adenoma (EPA) is rarely encountered. Although it originates from the adenohypophysis, it is sep-arated from the pituitary gland, being most often detected in the sphenoid sinus, suprasellar region, clivus, and cavernous sinus (2). Its occurrence in the spheno-orbital region has not been reported previously. We present such a case. CASE REPORT A 66-year-old man presented with a 2-month history of right proptosis and double vision. Our examination dis-closed that visual acuity was 20/20 in both eyes and visual fields were intact. A bulge of his right temporal region was evident, and there was mild proptosis of the right eye, with a Hertel exophthalmometry (TMI-90, T.M.I. Company, Ltd., Saitama, Japan) reading of 22 mm on the right and 14 mm on the left. There was a complete right abduction deficit. No clinical signs of Cushing disease, acromegaly, or hyperthyroidism were detected. Routine biochemical investigations were within normal limits. Brain MRI showed an irregular solid enhancing mass, approximately 3.5 cm 3 4 cm3 4 cm in size, located at the junction of the right orbital cavity and middle cranial fossa (Fig. 1A-B). The pituitary gland, residing within a normal-sized sella turcica, was unaffected (Fig. 1C, large arrow). The tumor was slightly hyperdense on precontrast CT (Fig. 1D), and bone windowing revealed that the right lateral orbital wall and greater sphenoid wing were eroded by the tumor (Fig. 1E). The lesion was believed to be a meningioma or metastatic tumor. Right frontotemporal craniotomy revealed a soft gray-white tumor with a rich blood supply at the junction of the temporal polar epidural space and the orbital cavity. The lesion extended exteriorly through the eroded great sphe-noid wing into the temporalis muscle and anteriorly through the expanded superior orbital fissure into the orbit with anterolateral displacement of the intact periorbita. Medially the tumor encroached on the lateral wall of the sphenoid sinus and a fraction of the tumor seemed to protrude into the sinus. After resection of the intraorbital tumor, the orbital contents were covered with a gelatin sponge and fibrin glue, providing further support to the orbital cone. No extension of the tumor into the subdural space was detected, but the fact that the tumor had a poor plane of cleavage from the temporal dura in some places demonstrated its invasiveness. The tumor was totally excised with the involved dura. Frozen section suggested pituitary adenoma. Postoperative CT revealed apparent total excision of the tumor (Fig 1F). On sections stained with hematoxylin and eosin, the tumor was composed of small uniform chromophobic cells arranged in a sinusoidal pattern with cellular atypia (Fig. 2A). On histochemical staining, these cells showed negative reactivity to growth hormone (Fig. 2B) or other anterior Department of Neurosurgery (HW, WY, ZZ), Nanjing Medical University, Hangzhou First People's Hospital, Hangzhou, People's Republic of China; and Departments of Neurosurgery (WB, WX) and Pathology (FZ), Fudan University, Huashan Hospital, Shanghai, People's Republic of China. Address correspondence to Hao Wang, MD, Nanjing Medical Uni-versity, Hangzhou First People's Hospital, Department of Neuro-surgery, Hangzhou, Huan Sha Lu 261#, 310006, PR China; E-mail: capsomerew@gmail.com Wang et al: J Neuro-Ophthalmol 2010; 30: 135-137 135 Original Contribution Copyright © North American Neuro-ophthalmology Society.Unauthorized reproduction of this article is prohibited. pituitary hormones, but positive reactivity to neuron-specific enolase (not shown). This is the characteristic staining pattern of a hormonally inactive pituitary adenoma. The patient's postoperative course was uneventful. Serum levels of anterior pituitary hormones were normal. No new neurologic deficits in addition to pulsatile proptosis were observed. Threemonths after surgery, the proptosis was gone, with Hertel readings of 15 mm on both sides. Eye move-ments were normal, and diplopia was no longer present. DISCUSSION Most spheno-orbital tumors are meningiomas, fibrous dysplasias, plexiform neurofibromas, or metastatic tumors. Mesenchymal chondrosarcoma, angiosarcoma, and encephalocele are other unusual spheno-orbital lesions (3-5), but as far as we are aware, EPA in the spheno-orbital region has never been reported. The putative origin of infrasellar EPAs differs from that of suprasellar EPAs, which are supposed to come from ectopic non-neoplastic pituitary cells in the leptomeninges of the suprasellar peri-infundibular region (6). Remnants of the developing tissue are often deposited along the route of upward migration of Rathke's pouch from the third to seventh week of gestation (7). Conceivably, these ectopic remnant cells around the sella and nasopharynx can be stimulated by several genetic and environmental factors to eventually develop into pituitary tumors (8). As for the present case, we hypothesize that the remnant cells of Rathke's pouch may have migrated into the lateral wall of the sphenoid sinus and undergone a neoplastic proliferation in this location. With bone eroded, the lesion probably broke through the medial margin of the superior orbital fissure to occupy the medial part of the fissure. It probably grew in 2 directions: posterolaterally toward the temporal polar epidural space and anterolaterally to destroy the thin edge of the greater sphenoid wing and invade the orbit. The preoperative diagnosis of hormonally inactive EPAs is quite difficult from that of hormonally active EPAs, because patients with the former do not show any endocrine symptoms and signs. The main clinical manifestations are headache or sinus fullness, nasal congestion, and cranial nerve paralysis caused by the tumor invasion of the sphe-noid sinus, nasal cavity, and cavernous sinus, respectively FIG. 1. A. Precontrast T1 axial MRI shows an extraaxial isointense solid mass at the junction of the right orbital cavity and middle cranial fossa. B. Postcontrast T1 axial MRI shows dense enhancement of the tumor. C. Postcontrast sagittal MRI shows a normal pituitary gland (arrow). D. Precontrast axial CT shows that the tumor is slightly hyperdense. E. Precontrast axial CT at bone window setting shows erosion of the right lateral orbital wall and the greater sphenoid wing by the tumor (arrows). F. Postoperative precontrast CT shows complete excision of the tumor. FIG. 2. Histopathologic analysis of the tumor (3400). A. Hematoxylin and eosin stain shows that the tumor is composed of small uniform chromophobic cells arranged in a sinusoidal pattern with cellular atypia. B. Growth hormone stain shows no immunoreactivity. Original Contribution 136 Wang et al: J Neuro-Ophthalmol 2010; 30: 135-137 Copyright © North American Neuro-ophthalmology Society.Unauthorized reproduction of this article is prohibited. (9-11). Visual disturbances result from impingement on the optic nerves or chiasm by suprasellar EPAs (12,13). However, unilateral exophthalmos is extremely rare, with only 1 case described previously (14). In that case, a pro-lactin- secreting EPA was found in the sphenoid sinus with extension to the clivus and medial aspect of the middle cranial fossa. The proptosis, which was attributed to oc-clusion of ophthalmic veins, disappeared 1 year after sur-gery. In our patient, the proptosis was most likely caused by direct compression of the orbital contents by the tumor and was understandably relieved quickly after total removal of the tumor. On CT, EPAs appear relatively isodense or slightly hyperdense with distinct margins. MRI of this lesion shows isointensity on T1 images, slight hyperintensity on T2 images, and uniform enhancement, a pattern similar to that seen in spheno-orbital meningiomas. Differentiating be-tween EPAs and the more common meningiomas is im-portant because patients with meningiomas are more likely to need invasive surgical techniques, have more frequent surgical complications, and have a less favorable clinical outcome (15). Features that favor the diagnosis of EPA over meningioma are epidural location of the tumor, sur-rounding bone erosion, and absence of marked hyperostosis and carpet-like dural involvement. Other possible diagnoses after imaging studies in the spheno-orbital region include fibrous dysplasia, peripheral nerve sheath tumor, and metastatic tumor. In this location, a neuroendocrine car-cinoma or an undifferentiated carcinoma are additional diagnostic considerations. A correct distinction is important because EPAs have a much more favorable prognosis and a low metastatic potential. The clues to diagnosis of an EPA are an endocrine growth pattern, a very low mitotic count, and evidence of neuro-endocrine markers and pituitary hormones. Hormonally inactive EPAs are usually cellular and composed of the chromophobic, small- to medium-sized monomorphic cells arranged in a sinusoidal pattern. Some pseudorosettes may be present. Mitotic cells are rare in the presence of nuclear atypia. The usual immunohistochemical pattern shows negativity for all anterior pituitary hormones and positivity for neuron-specific enolase (16), features seen in our patients. Early diagnosis and treatment of patients with EPAs could potentially lead to improved outcomes. Complete surgical removal should be attempted. If this cannot be achieved, postoperative radiotherapy is recommended (17). Our experience, limited as it is, indicates that complete surgical removal of this spheno-orbital lesion is quite safe and effective. However, in 2002, Hosaka et al (18) reported a patient with invasive EPA with malignant transformation after repeated relapses. In that patient, an EPA-producing follicle-stimulating hormone was found in the nasal cavity and extended to the frontal cranial fossa. Despite repeated surgical resections of the tumor, it recurred 3 times in 2 years. The patient died of the tumor 10 months after the last resection with multiple metastases in the subarachnoid space and brain parenchyma. The biologic behavior of EPAs will remain unclear until a longer follow-up in a larger patient cohort is available. Meanwhile, patients with these lesions, especially the invasive ones, should be followed closely. REFERENCES 1. Erdheim J. Kleinere Mitteilungen u¨ber einen Hypophysentumor von ungewo¨hnlichem Sitz. Beitr Pathol Anat. 1909;46:233-240. 2. 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