Pituitary Disease-Update

SE-4-1

A Few Things About Pituitary Adenoma Pathology

donaLd MIng-TaK Ho

Department of Pathology and Lab. Medicine, Taipei Veterans General Hospital Department of Pathology, National Yang Ming U. School of Medicine

Pituitary adenomas are benign neoplasm of adenohypophysial cells and consist of 10% of surgically removed intracranial neoplasms. The classification of pituitary adenomas has been evolved through histologic classification, ultrastructral classification, and immunohistochemical classification. In our institute, we adopt immunohistochemical classification using immunohistochemical staining of all pituitary hormones, i.e., PRL, GH, ACTH, FSH, LH, and TSH to classify pituitary adenomas since 1985. It was found that gonodotroph adenoma and plurihormonal adenoma are the most commonly encountered tumors, the former consists of around 1/3 of cases and the latter consists of slightly more than 1/4 of the pituitary adenomas in our surgical pathology file. In this presentation, the key features of these two tumors are presented based on the observations of our materials. As though the majority of pituitary adenomas are slow growing tumors, some are more aggressive and have a faster growth rate. By using MIB-LI, the most useful proliferative marker to date, the growth velocity of pituitary adenomas could be estimated. The presentation is based on our published materials and detailed information could be obtained from the references listed below.

references:

1. Ho DM, Hsu CY, Ting LT, Chiang H. The clinicopathological characteristics of gonadotroph cell adenoma: A study of 118 cases. Hum Pathol 1997; 28: 905-11. 2. Ho DM, Hsu CY, Ting LT, Chiang H. Plurihormonal pituitary adenomas: immunostaining of all pituitary hormones is mandatory for correct classification. Histopathology 2001; 39:310-9. 3. Hsu CY, Guo WY, Chien CP, Ho DM*. MIB-1 labeling index correlated with magnetic resonance imaging detected tumor volume doubling time in pituitary adenoma. Eur J Endocrinol 2010; 162:1027-33. (*corresponding author)

SE-4-2

Recent Advances in Pituitary Disease: Hypophysitis

JusTIn gIng-sHIng won

Division of Endocrinology and Metabolism, Department of Medicine, Taipei-Veterans General Hospital, Taiwan, R.O.C.

Hypophysitis, a rare but increasing recognized case of pituitary dysfunction, is a chronic inflammation of the pituitary and can be classified according to etiology, anatomic location, or histopathology. Etiology distinguishes hypophysitis into primary (or idiopathic) or secondary depending on whether the cause of the disease is unknown or identifiable. In terms of the anatomical regions affected, hypophysitis is also subdivided into 3 subtypes: adenohypophysitis- involving mainly the anterior lobe, infundibuloneurohypophysitis- involving mainly the stalk and posterior lobe, and panhypophysitis- involving both structures. Histologically, primary hypophysitis is further classified into 2 main forms of hypophysitis: lymphocytic (1962) and granulomatous (1916). During the past 2 decades, however, the clinicopathological spectrum of primary hypophysitis has expanded with the addition of 3 new forms: necrotizing (1993), xanthomatous (1999), and IgG4 plasmacytic (2004).

Primay lymphocytic hypophysitis, the most common subtype, is histologically characterized by diffuse lymphocytic infiltration with predominance of T cells, particularly CD4 cells. It is more common in young adult women and usually presents with symptoms originating from compression of sellar structures- headaches or visual disturbances, deficiency of anterior pituitary hormone production, with ACTH deficiency being the most frequent (32%), or diabetes insipidus (DI).

Granulomatous hypophysitis, the second most common subtype, affects males and females in equal proportion, and presents initially with symptoms/signs of mass effects from an enlarged pituitary gland, and later with 2 clinical manifestations; namely, central DI and panhypopituitarism. Histologically, it is characterized by multinucleated giant cells that from true granulomas with palisading histiocytes, surrounded by numerous lymphocytes, mainly T cells, and some plasma cells. Xantomatous hypophysitis is more common in women and is characterized by infiltration of foamy histiocytes and macrophages, accompanied by plasma cells, and lymphocytes. Only 4 cases of necrotizing hypophysitis has been reported till now so far. IgG4 plasmacytic hypophysitis, also called IgG4-related hypophysitis, is more common in men and advanced ages, presenting with central DI, ACTH deficiency, and ones from sellar compression due to an enlargement of the anterior pituitary and/or stalk as shown on sellar MRI. Histologically, it is characterized by the infiltration with numerous plasma cells, mainly the IgG4 plasmacytic form and predominantly produce antibodies of the IgG4 subclass. In this section, we will briefly review each subtype of hypophysitis and will share our experiences with 2 histologically proven cases of lymphocytic adenohypophysitis and another clinically proven case of IgG4-related hypophysitis.

SE-4-3

Surgical Treatment of Pituitary Tumors

CHIung-CHYI sHen

Minimally Invasive Neurosurgery, Taichung Veterans General Hospital, Taiwan, R.O.C.

Since Schloffer’s first description, the surgical treatment of pituitary tumors underwent significant evolution in the past century. To date, endonasal transsphenoidal microsurgery is the surgical treatment of choice for over 90% of pituitary tumours, but still transcranial operations are needed even in experienced hands in the large pituitary tumours with minor intrasellar components. Due to its excellent visualization through the endoscope, the implementation of intra-operative magnetic resonance (MR) imaging, minimal invasive endonasal endoscopic microsurgery for pituitary tumor has become widespread recently. The combination with stereotactic neuronavigational techniques offers accurate localization and superior anatomical details to help remove the tumor radically. We will discuss the different techniques, methods for removal various types of pituitary tumors.

The use of vasoconstrictors and any form of nasal packing was unnecessary. The inferior margin of the middle turbinate and choana were a consistent surgical landmark leading to the sella. The use of an intraoperative fluoroscopic C-arm was also eliminated. The adoption of a nasal spectum, variously angled suction cannulas and suction-coagulators has made the operation easier and faster. As experience increased, the operation time progressively shortened and mucosal trauma became minimal. Minimal complications and no mortality related to the approach were encountered in any patients in the follow-up period.

In microadenomas, the success rate reported from expert authors approaches 80%. Generally speaking, patients with non-functioning pituitary adenomas, acromegaly, ACTH-secreting and TSH-secreting adenomas are excellent candidates for primary surgical treatment. Re-operations are generally associated with less favourable outcomes. In prolactinomas, the primary therapy is medical; however, when dopamine agonists are not well tolerated or inefficient, an operative treatment should be considered. Although alternative medical treatments exist in acromegaly and thyrotropinomas, surgical treatment is relatively cheap.

Conclusion: The endonasal endoscopic transsphenoidal microsurgery for pituitary tumors provide adequate visualization of operative fileds and wide exposure of the tumor. It can increase the total-resection rate in both microadenoma and macroadenoma with minimal morbidities.

Key words: Endonasal, Endoscopic, Transsphenoidal, Pituitary Macroadenoma,

SE-4-4

Stereotactic Radiosurgery for Pituitary Tumors

XIao Furen

Division of Neurosurgery, National Taiwan University Hospital

Surgery remains the treatment of choice in management of pituitary tumor except some prolactinoma. However, total adenomectomy is not achievable in some situation. Conventional radiotherapy had been used as one of adjuvant therapies. Although it is effective to control the lesion but the treatment field is relatively large and the course takes several weeks.

Stereotactic radiosurgery (SRS) was used to replace the role of conventional radiotherapy. Single fraction or hypofraction SRS provides precise coverage of the tumor with low radiation dose to surrounding normal tissue. For nonfunctional tumor, the tumor control rate is high. For the growth hormone secreting tumor, the endocrinological normalization takes several years with a successful rate around 60%. As the majority of prolactinoma respond well to dopamine agonist, SRS is less frequently used. The success of SRS to ACTH secreting tumor was reported to be 80%, as fast as 2 years. In order to protect the vision, at least 2mm distance between the lesion and optic apparatus is desired in single fraction SRS. Hypopituiatrism occurs in some cases.

SRS is applied to treat the pituitary tumor with good tumor control, both in volume and in endocrinology. Preservation of vision and pituitary function can be achieved with proper patient selection and careful dose planning.