TSH-secreting pituitary adenomas: follow-up of 11 cases and review of the literature

A challenging TSH/GH co-secreting pituitary adenoma with concomitant thyroid cancer; a case report and literature review

BACKGROUND

Thyroid stimulating hormone (TSH) secreting pituitary adenoma (TSHoma) with coexisting thyroid cancer is extremely rare, and proper treatment of both diseases may pose a unique clinical challenge. When TSHoma has plurihormonality, particularly involving the co-secretion of growth hormone (GH), management can be more complicated. Herein, we present a difficult-to-manage case of papillary thyroid cancer with an incurable TSH/GH-secreting pituitary adenoma.

CASE PRESENTATION

A 59-year-old man was referred to our hospital due to memory impairment and inappropriate TSH level. Sella magnetic resonance imaging revealed a huge pituitary mass extending to the suprasellar area. Clinical diagnosis of TSH/GH co-secreting pituitary adenoma was made based on elevated free T4, total T3, serum α-subunit, insulin-like growth factor-1 levels and non-suppressible GH levels after oral glucose loading. Rectal cancer and multifocal papillary thyroid microcarcinoma (PTMC) were diagnosed during initial screening for internal malignancy; lower anterior resection was performed and close observation was planned for PTMC. Long-acting octreotide therapy was commenced, which resulted in a dramatic reduction in TSHoma size and facilitated control of hormonal excess. Total thyroidectomy and radioactive iodine (RAI) therapy were needed during follow up due to the growth of PTMC. After the surgery, the pituitary adenoma represented resistance to somatostatin analogue therapy and the tumor size gradually increased despite the addition of dopamine agonist therapy. Furthermore, TSH suppressive therapy with levothyroxine was impossible and an adequate TSH level for RAI therapy was unmountable. Late debulking pituitary surgery was ineffective, and the patient gradually deteriorated and lost to follow up.

CONCLUSION

We report the first aggravated case of TSH/GH co-secreting pituitary tumor after total thyroidectomy for concomitant multifocal PTMC. Deferring of thyroid surgery until the TSHoma is well controlled may be the optimal therapeutic strategy in patients with TSHoma and coexistent thyroid cancer; ablative thyroid surgery may result in catastrophic pituitary tumor growth.

Diagnosis, pathology, and management of TSH-secreting pituitary tumors. A single-center retrospective study of 20 patients from 1981 to 2014

TSH (thyroid-stimulating hormone)-secreting tumors are the rarest type of pituitary tumor. The objective of this study was to describe initial presentation and follow-up in patients presenting TSH-secreting tumors and to characterize the pathological features, based on a cohort of 20 patients treated in our referral center, between 1981 and 2014. Most of the patients (75%) were female, aged around 50 years (mean: 50±13 years). Initial symptoms were hyperthyroidism (8/20) and/or tumor mass-related symptoms. Median time to diagnosis was 18 months. Biochemical hyperthyroidism was found in 15 patients. Most of the tumors were macroadenomas (75%) and 30% were invasive. Seventeen patients underwent transsphenoidal surgery. All tumors expressed TSH, with>50% positive cells. Eleven were monohormonal and 6 plurihormonal, expressing βTSH plus growth hormone (GH) and/or prolactin (PRL). Both subtypes showed high expression of Pit-1 and SSTR_2A somatostatin receptors. SSTR₅ was slightly expressed in the plurihormonal subtype. Ki-67 index was elevated (≥3%) in only one tumor. Signs of hyperthyroidism were more frequent in the plurihormonal than in the monohormonal subtype. At final follow-up (median: 34.79±66.7 months), 75% of the patients were in complete remission after surgery; persistent hyperthyroidism was controlled by somatostatin analogs, alone (n=3) or associated to radiotherapy (n=1). The multidisciplinary approach promoted early diagnosis and control of hyperthyroidism by neurosurgical treatment, associated to somatostatin analogs or not. Clinical/pathological correlations highlighted the variations in immune profiles and in clinical and biological symptoms.

Thyrotoxicosis with concomitant thyroid cancer

Thyrotoxicosis with concomitant thyroid cancer is rare and poorly recognized, which may result in delayed diagnosis, inappropriate treatment and even poor prognosis. To provide a comprehensive guidance for clinicians, the etiology, pathogenesis, diagnosis and treatment of this challenging setting were systematically reviewed. According to literatures available, the etiologies of thyrotoxicosis with concomitant thyroid cancer were categorized into Graves' disease with concurrent differentiated thyroid cancer (DTC) or medullary thyroid cancer, Marine-Lenhart Syndrome with coexisting DTC, Plummer's disease with concomitant DTC, amiodarone-induced thyrotoxicosis with concomitant DTC, central hyperthyroidism with coexisting DTC, hyperfunctioning metastases of DTC and others. The underlying causal mechanisms linking thyrotoxicosis and thyroid cancer were elucidated. Medical history, biochemical assessments, radioiodine uptake, anatomic and metabolic imaging and ultrasonography-guided fine-needle aspiration combined with pathological examinations were found to be critical for precise diagnosis. Surgery remains a mainstay in both tumor elimination and control of thyrotoxicosis, while anti-thyroid drugs, beta-blockers, 131I, glucocorticoids, plasmapheresis, somatostatin analogs, dopamine agonists, radiation therapy, chemotherapy and tyrosine kinase inhibitors should also be appropriately utilized as needed.

Thyrotropin-secreting pituitary adenomas: a systematic review and meta-analysis of postoperative outcomes and management

PURPOSE

TSH-secreting pituitary adenomas are rare pituitary tumors. An efficient treatment is essential to limit the mortality and morbidity in untreated patients. The aim of this study is to summarize the evidence about the postoperative outcomes and management of this rare pathology.

METHODS

A systematic search and meta-analysis of surgical series was performed.

RESULTS

Our analysis included 23 articles (536 patients). No sex difference was observed and mean age at diagnosis was 45 years. Hyperthyroidism was reportedly clinical in 67% and biochemical in 90% of patients. Co-secretion of other pituitary hormones was present in 42% of cases. Macroadenomas were found in 79% of patients, showing in 44% and 30% of cases respectively extrasellar extension and cavernous sinus invasion. The pooled rate of postoperative biochemical remission was 69.7% and a gross total resection (GTR) was observed in 54% of patients. The extent of resection was significantly increased in microadenomas (p < 0.001) and cavernous sinus invasion was predictive of lower GTR rate (p < 0.001). A biochemical remission was achieved in 66% of patients after adjuvant radiation therapy and in 76% after adjuvant medical treatment. The combination of both allowed remission in 67% of cases. At final follow-up the overall biochemical remission rate was significantly improved (85.8%) when compared to the postoperative biochemical remission (p < 0.001).

CONCLUSION

When compared to the early postoperative period, at last follow-up biochemical remission was significantly greater (p < 0.001). GTR was achieved in half of patients; the size of tumor and cavernous sinus invasion determined the extent of resection.

Diagnosis and treatment of TSH-secreting adenomas: review of a longtime experience in a reference center

PURPOSE

TSH-secreting pituitary adenomas are among the less prevalent pituitary tumors, corresponding to 0.9-1.5% of all pituitary adenomas in surgical series.

METHODS

A series of 11 patients with TSH-secreting and cosecreting adenomas diagnosed and treated in the last 25 years in a single center is described.

RESULTS

The mean age at diagnosis was 37 years (range 18-80 years; median 23 years); the ratio of male-to-female patients was similar (6M:5F). Only three patients was the correct diagnosis established shortly after the initial medical evaluation. Other four patients were initially diagnosed with other pituitary adenomas (prolactinoma, acromegaly, and non-secreting pituitary tumor) and another four diagnosed with primary hyperthyroidism. There was a mean diagnostic delay of 6.0 years (range 0.5-25 years; median 2 years). Nine patients had macroadenomas and two patients had microadenomas. Seven patients underwent pituitary surgery which controlled the disease in only two (one micro- and one noninvasive macroadenoma). The other treatments were directed to the thyroid gland (surgery or ¹³¹I radiotherapy), pituitary radiotherapy, and somatostatin analog.

CONCLUSION

In spite of its relatively straightforward diagnosis, which includes clinical/subclinical hyperthyroidism with or without goiter, increased free thyroxine and nonsuppressed TSH levels, and pituitary mass, the diagnosis of TSH-secreting and cosecreting adenomas was frequently unrecognized and thus much delayed. Serum alpha-subunit levels were high in nearly all patients with TSH-secreting adenomas and useful in excluding other conditions in the differential diagnosis. Proper indication and interpretation of simple laboratory tests should be emphasized in medical education to improve diagnostic accuracy.

DIAGNOSIS OF ENDOCRINE DISEASE: Diagnostic approach to TSH-producing pituitary adenoma

Thyrotropin (TSH)-secreting adenomas (TSHomas) are the rarest form of pituitary adenomas, and most endocrinologists will see few cases in a lifetime, if any. In most cases, the diagnostic approach is complicated and cases may be referred after being presented as a syndrome of inappropriate TSH secretion or as a pituitary mass. This review aims to cover the past, present and possible future diagnostic approaches to TSHomas, including different clinical presentations, laboratory assessment and imaging advances. The differential diagnoses will be discussed, as well as possible coexisting disorders. By evaluating the existing reports and reviews describing this rare condition, this review aims to present a clinically practical suggestion on the diagnosic workup for TSHomas, Major advances and scientific breakthroughs in the imaging area in recent years, facilitating diagnosis of TSHomas, support the belief that future progress within the imaging field will play an important role in providing methods for a more efficient diagnosis of this rare condition.

Thyrotropin-secreting pituitary adenomas: epidemiology, diagnosis, and management

Inappropriate secretion of TSH was first described in 1960 in a patient with evidence of hyperthyroidism and expanded sella on imaging. It was later found that a type of pituitary adenoma that secretes TSH (thyrotropinoma) was the underlying cause. The objective of the present review article is to summarize data on the epidemiology, pathogenesis, diagnosis, and management of thyrotropinomas. The prevalence of thyrotropinomas is lower than that of other pituitary adenomas. Early diagnosis is now possible thanks to the availability of magnetic resonance imaging and sensitive laboratory assays. As a corollary, many patients now present earlier in the course of their disease and have smaller tumors at the time of diagnosis. Treatment also has evolved over time. Transsphenoidal surgery is still considered definitive therapy. Meanwhile, radiation therapy, including radiosurgery, is effective in achieving tumor control in the majority of patients. In the past, radiation therapy was used as second line treatment in patients with residual or recurrent tumor after surgery. However, the availability of somatostatin analogs, which can lead to normalization of thyroid function as well as shrink these tumors, has led to an increase in the role of medical therapy in patients who are not in remission after pituitary surgery. In addition, dopamine agonists have shown some efficacy in the management of these tumors. Better understanding of the molecular pathogenesis of thyrotropinomas may lead to rationally designed therapies for patients with thyrotropinomas.

Somatostatin Analogue Treatment of a TSH-Secreting Adenoma Presenting With Accelerated Bone Metabolism and a Pericardial Effusion: A Case Report

Increased bone turnover and other less frequent comorbidities of hyperthyroidism, such as heart failure, have only rarely been reported in association with central hyperthyroidism due to a thyrotropin (TSH)-secreting pituitary adenoma (TSHoma). Treatment is highly empirical and relies on eliminating the tumor and the hyperthyroid state.We report here an unusual case of a 39-year-old man who was initially admitted for management of pleuritic chest pain and fever of unknown origin. Diagnostic work up confirmed pericarditis and pleural effusion both refractory to treatment. The patient had a previous history of persistently elevated levels of alkaline phosphatase (ALP), indicative of increased bone turnover. He had also initially been treated with thyroxine supplementation due to elevated TSH levels. During the diagnostic process a TSHoma was revealed. Thyroxine was discontinued, and resection of the pituitary tumor followed by treatment with a somatostatin analog led to complete recession of the effusions, normalization of ALP, and shrinkage of pituitary tumor.Accelerated bone metabolism and pericardial and pleural effusions attributed to a TSHoma may resolve after successful treatment of the tumor. The unexpected clinical course of this case highlights the need for careful long-term surveillance in patients with these rare pituitary adenomas.

Clinical outcome and evidence of high rate post-surgical anterior hypopituitarism in a cohort of TSH-secreting adenoma patients: Might somatostatin analogs have a role as first-line therapy?

PURPOSE

Thyrotropin-secreting pituitary adenomas (TSHomas) represent a rare subtype of pituitary tumors. Neurosurgery (NCH) is still considered the first-line therapy. In this study we aimed to investigate the outcome of different treatment modalities, including first line somatostatin analogs (SSA) treatment, with a specific focus on neurosurgery-related complications.

METHODS

We retrospectively evaluated thirteen patients diagnosed for TSHomas (9 M; age range 27-61). Ten patients had a magnetic resonance evidence of macroadenoma, three with slight visual field impairment. In the majority of patients, thyroid ultrasonography showed the presence of goiter and/or increased gland vascularization. Median TSH value at diagnosis was 3.29 mU/L (normal ranges 0.2-4.2 mIU/L), with median fT4 2.52 ng/dL (0.9-1.7 ng/dL).

RESULTS

Three patients (two microadenoma) were primarily treated with NCH and achieved disease remission, whereas ten patients (nine macroadenomas) were initially treated with SSA. Despite the optimal biochemical response observed during medical treatment in most patients (mean TSH decrease -72%), only two stayed on medical therapy alone, achieving stable biochemical control at the end of the follow-up. The remaining patients (n = 7) underwent NCH later on during their clinical history, followed by radiotherapy or adjuvant SSA treatment in two cases. Noteworthy, five of them developed hypopituitarism. All patients reached a biochemical control, after a multimodal therapeutic approach.

CONCLUSIONS

Neurosurgery ultimately led to complete disease remission or to biochemical control in majority of patients, whereas resulting in a considerable percentage of post-operative complications (mainly hypopituitarism, 50%). In the light of the optimal results unanimously reported for medical treatment with SSA, our experience suggests that a careful evaluation of risk/benefit ratio should be taken into consideration when directing the treatment approach in patients with TSHoma.

Primary Medical Treatment of Thyrotropin-Secreting Pituitary Adenomas by First-Generation Somatostatin Analogs: A Case Study of Seven Patients

BACKGROUND

The first-choice treatment of thyrotropin (TSH)-secreting pituitary adenomas is surgical adenomectomy, with 40-60% of patients cured after surgery. The presence of somatostatin receptors on the adenomatous cells suggests that first-generation somatostatin analogs (octreotide, lanreotide) could be used as an adjuvant treatment to surgery for TSH-secreting pituitary adenomas. The aim of this study is to describe the efficacy and safety of primary medical treatment with first-generation somatostatin analogs in patients with a TSH-secreting pituitary adenoma.

METHODS

Retrospective study on 7 patients (5 women, 2 men) aged 57±14 years with pure TSH (n=4) or mixed TSH/GH (n=3) secreting pituitary adenomas primarily treated with first generation somatostatin analogs. Magnetic resonance imaging revealed a microadenoma in 3 patients and a macroadenoma in 4 patients. The follow-up period was 8.5±7.3 years.

RESULTS

At initial diagnosis, the patients presented with thyrotoxicosis with elevated free thyroxine (26.5±6.5 pg/mL) and free triiodothyronine (7.3±0.9 pg/mL) levels and a mean TSH of 4.3±1.4 mU/L. During somatostatin analog treatment, free thyroid hormones and TSH levels normalized after 4.4±3.9 and 7.0±8.4 months, respectively. At the time of the last visit, 6 patients were biochemically controlled. Adenoma volume decreased in 6 patients and a decrease in adenoma volume persisted in 2 patients several years after initiation of somatostatin analog treatment. Safety of treatment was good and no patients discontinued somatostatin analogs due to side effects.

CONCLUSION

This study confirms the efficacy of primary medical treatment with first-generation somatostatin analogs in terms of hormonal control and tumor volume reduction in patients with TSH-secreting pituitary adenomas, and its good safety profile. First-generation somatostatin analogs may serve as a medical alternative to surgical treatment, especially in patients where surgery is contraindicated or in subjects presenting with invasive macroadenomas that render complete surgical resection difficult.

Is the incidence of differentiated thyroid cancer increased in patients with thyrotropin-secreting adenomas? Report of three cases from a large consecutive series

BACKGROUND

Patients with a thyrotropin-secreting pituitary adenoma (TSHoma) are exposed to unregulated and inappropriately high levels of thyrotropin (TSH). Given the rarity of this condition, it is not known whether this chronic TSH stimulation of the thyroid gland might represent a risk factor for the development of differentiated thyroid cancer (DTC). We analyzed the incidence of DTC in a large cohort of patients with TSHomas.

METHODS

The study population consisted of all consecutive patients who underwent neurosurgery for a TSHoma between 1990 and 2013. Criteria for the diagnosis of TSHoma in patients without previous thyroid ablative procedures included elevated free thyroid hormones and normal/high serum TSH concentrations, presence of a lesion at magnetic resonance imaging (MRI), and abnormal response of TSH to at least one dynamic test. Patients who had received thyroid ablative procedures were required to have a pituitary lesion on MRI and TSH levels not suppressed while on levothyroxine therapy at doses causing elevation of free thyroid hormone levels.

RESULTS

Sixty-two patients (32 females, 30 males) underwent surgery for a TSHoma at our center. Among them, 3 patients had a coexistent diagnosis of DTC with an estimated incidence of 4.8%. In 2 patients, DTC was diagnosed during the evaluation for suspected TSH-dependent hyperthyroidism, whereas in the third patient, diagnosis of DTC preceded the detection of the pituitary tumor.

CONCLUSIONS

The elevated incidence of DTC in patients with TSHoma suggests a possible role of TSH hypersecretion in the development of thyroid tumors. A formal high-resolution ultrasound of the thyroid is recommended in patients diagnosed with a TSHoma, especially if a long history of the pituitary tumor is suspected. Moreover, suspicion about the presence of TSHoma should be raised by the lack of suppression of TSH levels despite adequate doses of levothyroxine after thyroidectomy for DTC.

Evaluation and management of thyrotropin-secreting pituitary adenomas

Thyrotropin (TSH)-secreting pituitary adenomas are uncommon pituitary neoplasms. They have been increasingly recognized with the advent of ultrasensitive TSH assays and advanced pituitary imaging. Clinically, patients may often present with signs and symptoms of hyperthyroidism. Some patients may present with tumor-related local mass effect, anterior hypopituitarism or syndromes related to co-secretion of other pituitary hormones. Their diagnosis and differential diagnosis from other causes of hyperthyroidism and ‘inappropriate TSH secretion’ often presents a clinical challenge. While trans-sphenoidal pituitary adenomectomy remains the therapeutic modality of choice, medical treatment with somatostatin receptor agonists or dopamine agonists is often needed as adjunctive therapy or perhaps as a potential alternative to surgery. Radiation therapy to the sella may be advised as a third-line therapy.

Clinicopathological characteristics and therapeutic outcomes in thyrotropin-secreting pituitary adenomas: a single-center study of 90 cases

OBJECT

The aim of this study was to analyze clinicopathological characteristics and treatment outcomes in a large single-center clinical series of cases of thyrotropin (TSH)-secreting pituitary adenomas.

METHODS

The authors retrospectively reviewed clinical, pathological, and treatment characteristics of 90 consecutive cases of TSH-secreting pituitary adenomas treated with transsphenoidal surgery between December 1991 and May 2013. The patient group included 47 females and 43 males (median age 42 years, range 11-74 years).

RESULTS

Sixteen tumors (18%) were microadenomas and 74 (82%) were macroadenomas. Microadenomas were significantly more frequent in the more recent half of our case series (12 of 45 cases) (p = 0.0274). Cavernous sinus invasion was confirmed in 21 patients (23%). In 67 cases (74%), the tumors were firm elastic or hard in consistency. Acromegaly and hyperprolactinemia were observed, respectively, in 14 (16%) and 11 (12%) of the 90 cases. Euthyroidism was achieved in 40 (83%) of 48 patients and tumor shrinkage was found in 24 (55%) of 44 patients following preoperative somatostatin analog treatment. Conventional transsphenoidal surgery, extended transsphenoidal surgery, and a simultaneous combined supra- and infrasellar approach were performed in 85, 2, and 3 patients, respectively. Total removal with endocrinological remission was achieved in 76 (84%) of 90 patients, including all 16 (100%) patients with microadenomas, 60 (81%) of the 74 with macroadenomas, and 8 (38%) of the 21 with cavernous sinus invasion. None of these 76 patients experienced tumor recurrence during a median follow-up period of 2.8 years. Stratifying by Knosp grade, total removal with endocrinological remission was achieved in 34 of 36 patients with Knosp Grade 0 tumors, all 24 of those with Grade 1 tumors, 12 of the 14 with Grade 2 tumors, 6 of the 8 with Grade 3 tumors, and none of the 8 with Grade 4 tumors. Cavernous sinus invasion and tumor size were significant independent predictors of surgical outcome. Immunoreactivity for growth hormone, prolactin, or both hormones was present in 32, 9, and 24 patients, respectively. The Ki-67 labeling index was less than 3% in 71 (97%) of 73 tumors for which it was obtained and 3% or more in 2. Postsurgery pituitary dysfunction was found in 15 patients (17%) and delayed hyponatremia was seen in 9.

CONCLUSIONS

TSH-secreting adenomas, particularly those in the microadenoma stage, have increased in frequency over the past 5 years. The high surgical success rate achieved in this series is due to relatively early diagnosis and relatively small tumor size. In addition, the surgical strategies used, such as extracapsular removal of hard or solid adenomas, aggressive resction of tumors with cavernous sinus invasion, or extended transsphenoidal surgery or a simultaneous combined approach for large/giant multilobulated adenomas, also may improve remission rate with a minimal incidence of complications.

A long-term follow-up study of eighteen patients with thyrotrophin-secreting pituitary adenomas

OBJECTIVE

TSH-secreting pituitary adenomas (TSH-omas) are a rare cause of thyrotoxicosis. First-line therapy for these tumours is neurosurgery, although medical therapy with somatostatin analogues (SSAs) is increasingly used for this indication.

DESIGN AND PATIENTS

We retrospectively reviewed the data of patients with a TSH-oma (n = 18, 67% males) followed between 1989 and 2011 (median follow-up 7 years, range 1-21) in three academic medical centres in the Netherlands, focusing on the role of SSA treatment.

MEASUREMENTS

Patient records were reviewed for clinical, biochemical, imaging, pathological and treatment characteristics.

RESULTS

At initial evaluation, biochemical hyperthyroidism with non-suppressed TSH concentrations was detected in 94% of the patients. The majority of patients (72%) had a macroadenoma with extrasellar extension. Fourteen patients underwent surgery, resulting in postoperative euthyroidism in six patients (43%). Recurrence of hyperthyroidism developed in three of them after 5, 24 and 32 months, respectively. Adjuvant radiotherapy (n = 2) did not induce remission. Three patients received SSA therapy exclusively, resulting in apparent cure in one of them. During long-term follow-up, 72% of all patients required medical therapy (mostly SSA treatment). Euthyroidism was achieved in all but one patient, who refused all treatments.

CONCLUSIONS

Our results demonstrate that patients with TSH-omas, who often present with large macroadenomas with extrasellar extension, have an excellent response to SSA therapy. Because the results of surgery and radiotherapy are disappointing, primary medical therapy may be considered in virtually all patients, except in case of optic chiasm compression, especially in those harbouring large adenomas with parasellar extension.

Thyrotropin-secreting pituitary tumor presenting with congestive heart failure and good response to dopaminergic agonist cabergoline

Hyperthyroidism is an important inducing factor in patients with atrial fibrillation, and may trigger heart failure. Thyrotropin (thyroid stimulating hormone, TSH)-secreting pituitary tumors are rare causes of hyperthyroidism. Here, we report a 66-year-old man with a pituitary TSH-secreting tumor who presented with hyperthyroidism and congestive heart failure. Endonasal trans-sphenoidal pituitary adenomectomy was performed. After the operation, the symptoms of hyperthyroidism and congestive heart failure were relieved, associated with normalization of thyroid function tests. Unfortunately, hand tremor and progressively elevated free T4 and TSH concentrations recurred 5 months after surgery. A dopaminergic agonist, cabergoline was administered and euthyroidism was restored for at least 11 months.

Thyrotropin-secreting adenoma in a patient with primary hypothyroidism

OBJECTIVE

To describe a patient who developed a thyrotropin (TSH)-secreting adenoma in the setting of primary hypothyroidism.

METHODS

We report the clinical, laboratory, and radiologic findings of a patient with a history of primary hypothyroidism who presented with headache, a bitemporal visual field deficit, and elevated TSH despite long-term levothyroxine therapy. We discuss the diagnostic challenges of this case and review the relevant literature.

RESULTS

A 54 year old woman with a history of primary hypothyroidism presented with a 3-year history of headache and a week of worsening vision. Imaging revealed a heterogeneous sellar mass elevating the optic chiasm. Her serum TSH was 46.5 mIU/L and free thyroxine concentration was 0.1 ng/dL. The differential diagnosis included pituitary hyperplasia and a TSH-secreting adenoma in a patient with primary hypothyroidism. The pathologic characteristics of the tumor were consistent with the latter.

CONCLUSION

In a patient with an elevated TSH concentration and a previous diagnosis of hypothyroidism, it is important to consider other entities besides medication noncompliance. TSH-secreting adenomas can also cause elevated levels of TSH.

Thyroid-stimulating hormone (thyrotropin)-secretion pituitary adenoma in an 8-year-old boy: case report

In this report, an extremely rare case of pediatric thyrotropin-secreting pituitary macroadenoma (TSHoma) is described. An 8-year-old boy, complaining of unsteady gait, was suspected of endocrinopathy because of emaciation and muscle weakness of the legs. Endocrinological work-up established a diagnosis of hyperthyroidism due to syndrome of inappropriate secretion of TSH. Magnetic resonance imaging showed a pituitary macroadenoma with suprasellar and sphenoidal extension without cavernous sinus invasion. He underwent an endoscopic endonasal transsphenoidal adenomectory due to the diagnosis of TSHoma. The adenoma was soft and it was totally removed. Histopathological staining confirmed diagnosis of TSHoma. Postoperative evaluation revealed a subnormal level of TSH (from 13-21 to 0.03 micro U/ml), normalization of alpha-subunit (from 10.0 to 0.09 ng/ml), and as a result, hypothyroidism. The boy left the hospital with oral levothyroxine that continued until 12 months of discharge. The present 8-year-old case is the youngest case to the best of our knowledge based on a bibliographical search. Reasons for endocrinological remission following adenomectomy are (1) correct diagnosis without delay: lack of cavernous sinus invasion, (2) soft and non-fibrous adenoma tissue, and (3) endoscopic technique with wide vision and illumination: safe even for a 8-year-old child. Early recognition/detection and pituitary-conserving adenomectomy can cure TSHoma and avoid long-term medical therapy and/or irradiation, which contribute to the best interests of patients with TSHoma.

Thyrotropin-secreting pituitary adenoma in an adolescent boy: challenges in management

Thyrotropinomas tend to be aggressive, invasive tumors that are difficult to resect because of their marked fibrosis and their proximity to vital structures such as the optic chiasm. The latter characteristic also limits the use of radiation therapy. In the few cases reported of children younger than 18 years whose thyrotropinomas were treated surgically, the results were disappointing. We present here the case of a 16-year-old boy with a thyrotropin-secreting pituitary macroadenoma who underwent partial resection via a transsphenoidal approach and was left with significant residual tumor and continued hyperthyroidism. He subsequently received 4 years of long-acting release somatostatin therapy, during which he has remained euthyroid without requiring antithyroid medication. To our knowledge, this is thus far the longest duration of somatostatin therapy in the pediatric age group. This regimen also achieved a decrease in compression of the optic nerve and prevented further tumor growth. We review here the current literature on somatostatin analog treatment including molecular mechanisms and promising new treatment modalities, such as the heterodimerization of dopamine and somatostatin receptors. We conclude that this has been a useful adjuvant treatment for our adolescent patient.

[TSH-secreting pituitary tumors: two case reports and literature review]

INTRODUCTION

TSH-secreting pituitary adenomas are rare pituitary functioning tumors accounting for less than 2% of the pituitary adenomas. The clinical feature consists of thyrotoxicosis occasionally associated to tumoral symptoms due to mass effect. The biochemical feature consists of elevated thyroid hormones levels and normal or high TSH concentrations. This disease is often wrongly diagnosed as Grave's disease, and the ablative therapy is frequently conducted prior to the diagnosis.

OBJECTIVE

To report two cases followed in the Neuroendocrine Unit of Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo and to review the literature aiming at the management of this affection.

CONCLUSION

In the presence of elevated thyroid hormone levels associated with inappropriate normal or increased TSH levels, the possibility of a TSH-secreting pituitary adenoma should be considered for the proper medical treatment.

Clinical aspects and therapeutic outcome in thyrotropin-secreting pituitary adenomas: a single center experience

BACKGROUND AND AIM

The management of pituitary adenomas secreting TSH has evolved considerably over the last decades.We report the clinical features, management, and outcome of a large monocentric series.

MATERIAL AND METHODS

A monocentric retrospective cohort of 26 patients admitted to our Department of Endocrinology between 1983 and 2007, followed for a period up to 204 months. The diagnosis of TSH-secreting adenoma was based on clinical and biochemical findings of central hyperthyroidism. Evaluation of basal and dynamic pituitary function, magnetic resonance imaging or computerized tomography scan were performed in all patients. Twenty-two patients, of whom 15 pre-treated by somatostatin analogs (SSA), underwent trans-sphenoidal surgery and were regularly re-evaluated.

RESULTS

The number of cases increased over the years. Age at diagnosis, micro- to macroadenoma ratio, and mean estimated latency between first symptoms and diagnosis did not appreciably change over time. Latency was significantly shorter in macroadenomas. Following surgery, 55% of patients obtained remission (success rate of 40 and 67% in macro- and microadenomas, respectively). SSA pre-treatment led to an apparent although not statistically- significant increase in success rate in micro- but not in macroadenomas.

CONCLUSIONS

In a monocentric group of 26 TSH-secreting adenomas the high ratio between micro- and macroadenomas remained stable over time with a significantly shorter diagnosis latency in macroadenomas. A more precocious recognition of the tumors and possibly the use of presurgical SSA allowed a high remission rate. A varied combination of neurosurgery, SSA, radiotherapy, and thyroid ablation led to the control of the disease in all the patients studied.

Pituitary tumours: TSH-secreting adenomas

Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism and account for less than 2% of all pituitary adenomas. In the last years, the diagnosis has been facilitated by the routine use of ultra-sensitive TSH immunometric assays. Failure to recognise the presence of a TSHoma may result in dramatic consequences, such as improper thyroid ablation that may cause the pituitary tumour volume to further expand. The diagnosis mainly rests on dynamic testing, such as T3 suppression tests and TRH, which are useful in differentiating TSHomas from the syndromes of thyroid hormone resistance. The first therapeutical approach to TSHomas is the pituitary neurosurgery. The medical treatment of TSHomas mainly rests on the administration of somatostatin analogues, such as octreotide and lanreotide, which are effective in reducing TSH secretion in more than 90% of patients with consequent normalisation of FT4 and FT3 levels and restoration of the euthyroid state.

Thyroid-stimulating hormone pituitary adenomas

Object

Thyroid-stimulating hormone (TSH)–secreting pituitary adenomas are rare, representing < 2% of all pituitary adenomas.

Methods

The authors conducted a retrospective analysis of patients with TSH-secreting or clinically silent TSH-immunostaining pituitary tumors among all pituitary adenomas followed at their institution between 1987 and 2003. Patient records, including clinical, imaging, and pathological and surgical characteristics were reviewed. Twenty-one patients (6 women and 15 men; mean age 46 years, range 26–73 years) were identified. Of these, 10 patients had a history of clinical hyperthyroidism, of whom 7 had undergone ablative thyroid procedures (thyroid surgery/131I ablation) prior to the diagnosis of pituitary adenoma. Ten patients had elevated TSH preoperatively. Seven patients presented with headache, and 8 presented with visual field defects. All patients underwent imaging, of which 19 were available for imaging review. Sixteen patients had macroadenomas.

Results

Of the 21 patients, 18 underwent transsphenoidal surgery at the authors' institution, 2 patients underwent transsphenoidal surgery at another facility, and 1 was treated medically. Patients with TSH-secreting tumors were defined as in remission after surgery if they had no residual adenoma on imaging and had biochemical evidence of hypo-or euthyroidism. Patients with TSH-immunostaining tumors were considered in remission if they had no residual tumor. Of these 18 patients, 9 (50%) were in remission following surgery. Seven patients had residual tumor; 2 of these patients underwent further transsphenoidal resection, 1 underwent a craniotomy, and 4 underwent postoperative radiation therapy (2 conventional radiation therapy, 1 Gamma Knife surgery, and 1 had both types of radiation treatment). Two patients had persistently elevated TSH levels despite the lack of evidence of residual tumor. On pathological analysis and immunostaining of the surgical specimen, 17 patients had samples that stained positively for TSH, 8 for α-subunit, 10 for growth hormone, 7 for prolactin, 2 for adrenocorticotrophic hormone, and 1 for follicle-stimulating hormone/luteinizing hormone. Eleven patients (61%) ultimately required thyroid hormone replacement therapy, and 5 (24%) required additional pituitary hormone replacement. Of these, 2 patients required treatment for new anterior pituitary dysfunction as a complication of surgery, and 2 patients with preoperative partial anterior pituitary dysfunction developed complete panhypopituitarism. One patient had transient diabetes insipidus. The remainder had no change in pituitary function from their preoperative state.

Conclusions

Thyroid-stimulating hormone–secreting pituitary lesions are often delayed in diagnosis, are frequently macroadenomas and plurihormonal in terms of their pathological characteristics, have a heterogeneous clinical picture, and are difficult to treat. An experienced team approach will optimize results in the management of these uncommon lesions.

Long term treatment of a thyrotropin secreting adenoma with somatostatin analogues

Thyrotropin secreting adenomas (TSH-omas) account for less than 1% of all pituitary adenomas and are a rare cause of hyperthyroidism. Most cases correspond to macroadenomas, microadenomas being exceptional. Differential diagnosis should be made with resistance to thyroid hormones. The first line treatment is transphenoidal surgery. When surgery is unsuccessful, somatostatin analogues are a therapeutic alternative. We report a patient with a TSH-secreting microadenoma. The microadenoma was resected through the transsphenoidal route. Because surgery was unsuccessful, medical therapy with somatostatin analogue was initiated. Currently, 9 years later, the patient continues to be under treatment with somatostatin analogue therapy, which has controlled the hyperthyroidism and tumoral growth. We describe successful long-term treatment of a TSH-oma with somatostatin analogue therapy when surgery is unsuccessful.