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TSH-Secreting Pituitary Macroadenoma in a Girl with Lingual Thyroid

DOI: 10.1155/2013/570847

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Abstract:

Patients with long-standing hypothyroid are, in some cases, reported to develop pituitary gland hyperplasia due to loss of feedback inhibition of thyroxine in hypothalamus—the condition of which typically regresses after thyroxine replacement. Herein, a 15-year-old girl—with long-standing untreated lingual hypothyroid—presents with a pathologically proven TSH pituitary macroadenoma and bilateral large ovarian cysts. Although MR imaging may differentiate between hyperplasia and macroadenoma of the pituitary gland, pathological examination is still a cornerstone to correct diagnosis. 1. Introduction Pituitary gland enlargement due to thyrotroph hyperplasia has been well documented in association with long-standing hypothyroidism. The mechanism can be explained by an overstimulation of thyrotrophs by thyrotropin-releasing hormone (TRH) in classic negative feedback loop. Patients with this condition may be asymptomatic or occasionally present with local neurological pressure effect such as visual field defect or squint. The pituitary gland hyperplasia could be reversible after thyroxine replacement and normalisation of serum TSH. We report, herein, an adolescent girl with undiagnosed long-standing congenital hypothyroidism due to lingual thyroid and pituitary gland enlargement which could not be reversible after thyroxine replacement. Histology confirmed the diagnosis of pituitary gland macroadenoma. 2. Case Report A 15-year-old girl presented with secondary amenorrhea with short stature, abdominal discomfort, and squint. She was born at term with normal birth weight and uneventful postnatal history; nevertheless, growing up, she was considered short compared with girls of the same age. Academically, she was average in class. Her menarche developed when she was 14 years of age; however, secondary amenorrhea had already occurred for 6 months prior to this presentation. On examination, her height and weight were 132?cm and 36?kg, which were on—5 Standard Deviation Score (SDS) and—2 SDS for standard Thai growth chart, respectively. She had breast Tanner III, pubic hair Tanner II. Ophthalmic examination revealed bilateral optic nerve atrophy. Ultrasonography demonstrated bilateral multicystic ovarian masses, 12.8 × 5.6 × 11.3?cm and 12 × 5.9 × 9?cm of the left and right sides, respectively. Free T4 level was 0.08?ng/dL ( : 0.8–1.8); TSH >100?mIU/L ( : 0.3–4.1); serum prolactin 45.4?ng/mL ( : 3–25); FSH 24.5?IU/L; LH <0.1?IU/L; and estradiol 15,469?mmol/L. Ectopic thyroid at sublingual area was detected by technetium thyroid scan. Because of the optic nerve

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