Unusual Type of Growth Hormone-Producing Pituitary Tumor in Acromegaly
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Unusual Type of Growth Hormone-Producing Pituitary Tumor in Acromegaly Satoshi Yamagata & Kazunori Kageyama & Satoru Sakihara & Shozo Yamada & Shinobu Takayasu & Shinji Chikazawa & Naoko Inoshita & Toshiaki Sano & Toshihiro Suda
Published online: 26 May 2012 # Springer Science+Business Media, LLC 2012
Introduction Acromegaly is primarily caused by a growth hormone (GH)-producing pituitary tumor, usually a somatotroph adenoma. Somatotroph adenomas have been histologically classified into two subtypes: densely granulated (DG) and sparsely granulated (SG), reflecting the number of secretory granules in the cytoplasm [1]. SG adenomas are mainly composed of cells possessing fibrous bodies, intracytoplasmic globular aggregates of cytokeratin (CK) filaments. CK filaments are found as dotlike structures in SG adenomas, whereas they are ringlike or perinuclear in DG adenomas [2–4]. In addition, it is important to distinguish between the two types of adenomas in terms of clinical behavior because SG adenomas are likely to be macroadenomas, show aggressive biological behavior, and respond poorly to octreotide, compared with their DG counterparts [5–7]. Magnetic resonance imaging (MRI) is useful for detecting GH-producing pituitary adenomas, with an accuracy of S. Yamagata : K. Kageyama (*) : S. Sakihara : S. Takayasu : S. Chikazawa : T. Suda Department of Endocrinology and Metabolism, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori 036-8562, Japan e-mail: [email protected] S. Yamada Department of Neurosurgery, Toranomon Hospital, 2-2-2 Toranomon, Minatoku, Tokyo 105-8470, Japan N. Inoshita : T. Sano Department of Pathology, Toranomon Hospital, 2-2-2 Toranomon, Minatoku, Tokyo 105-8470, Japan
97 % reported for conventional MRI [8]. Transsphenoidal surgery (TSS) is usually performed after the presence of a pituitary adenoma is confirmed by MRI. GH-producing adenomas are usually encapsulated, even in cases where MRI failed to detect a mass [8, 9]. We report here an unusual SG-type GH-producing pituitary tumor. In this case, the lesion showed fainter enhancement with 3 T MRI than the adjacent thin pituitary gland in the inferior left quadrant, suggesting a tumor in the pituitary gland associated with an empty sella.
Case Report A 39-year-old man was referred for evaluation of acromegaly in May 2010. On admission, his height was 161.5 cm, body weight 72.8 kg, and body mass index 27.7 kg/m2. He was hypertensive (188/112 mmHg) and had macroglossia, acropathy of the fingers and toes, and large lips and nose. He had been treated for a colon polyp with endoscopic polypectomy. All endocrine examinations were performed according to clinical guidelines, and informed consent for the tests was obtained from the patient. The basal GH level was 7.0 ng/ml (normal range for his age is
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