A thyrotropin-secreting macroadenoma with positive growth hormone and prolactin immunostaining: A case report and literature review

A Case of an Immature PIT1-Lineage Pituitary Neuroendocrine Tumor of the Nasopharynx

Pituitary neuroendocrine tumors (PitNETs) located in the nasopharynx are a rare occurrence. This case report highlights a case of a 64-year-old female diagnosed with a PitNET incidentally found in her nasopharynx. The tumor was initially seen on MRI, excised, and analyzed with immunohistochemistry, ultimately confirming an immature pituitary-specific positive transcription factor 1 (PIT1)-positive-lineage pituitary neuroendocrine tumor. The tumor contained thyrotropes, somatotrophs, and lactotrophs expressing thyroid stimulating hormone, growth hormone, and prolactin, respectively. These tumors have the potential to exhibit aggressive behavior and can disrupt the surrounding tissue. Furthermore, they can be clinically silent or, conversely, secrete multiple hormones, causing hyperthyroidism, hyperprolactinemia, and acromegaly. For these reasons, they are deemed high risk. Treatment includes surgical excision with or without anti-hormone medications prior to surgery. Medications such as somatostatin analogs are used to decrease tumor size and reduce excessive hormone excretion.

Pleiomorphism plurihormonal Pit-1-positive macroadenoma with central hyperthyroidism: a rare case report and literature review

BACKGROUND

Thyrotropin-secreting pituitary neuroendocrine tumors (PitNETs) are rare pituitary adenomas that are occasionally accompanied by hypersecretion of other anterior pituitary hormones, such as growth hormone (GH) and prolactin (PRL). The clinical, biochemical, and pathological characteristics may represent diverse circumstances.

CASE PRESENTATION

In this report, a 33-year-old female diagnosed with a TSH PitNET co-secreting GH presented no obvious clinical symptoms. The main characteristics were elevated thyroid-stimulating hormone (TSH), free tri-iodothyronine (FT3), and free thyroxine (FT4) levels accompanied by slightly elevated GH and insulin-like growth factor-1 (IGF-1) levels. Magnetic resonance imaging (MRI) detected a pituitary macroadenoma (18 × 16 × 16 mm) with cavernous sinus and suprasellar invasion. Immunohistochemistry revealed diffuse positivity for TSH, strong immunoreactivity for GH, and sporadic positivity for PRL. The electron microscope and double immunofluorescence staining confirmed a plurimorphous plurihormonal adenoma producing TSH, GH, and PRL. After preoperative somatostatin receptor ligand (SRL) treatment and transsphenoidal surgery, the patient achieved temporary clinical and biochemical remission. However, 3 months after surgery, the patient was suspected of having Hashimoto's thyroiditis due to higher thyroglobulin antibody (TGAb), thyroid peroxidase antibody (TPOAb), and thyroid receptor antibody (TRAb) and an enlarged thyroid nodule. During follow-up, thyroid function and TSH slowly transformed from transient hyperthyroidism to hypothyroidism. They were maintained in the normal range by L-T4.

CONCLUSION

In the TSH PitNET, the positive immunohistochemistry for TSH, GH, and PRL translated into hormonal overproduction with TSH and GH.

Clinical and Pathological Aspects of Silent Pituitary Adenomas

CONTEXT

Silent pituitary adenomas are anterior pituitary tumors with hormone synthesis but without signs or symptoms of hormone hypersecretion. They have been increasingly recognized and represent challenging diagnostic issues.

EVIDENCE ACQUISITION

A comprehensive literature search was performed using MEDLINE and EMBASE databases from January 2000 to March 2018 with the following key words: (i) pituitary adenoma/tumor and nonfunctioning; or (ii) pituitary adenoma/tumor and silent. All titles and abstracts of the retrieved articles were reviewed, and recent advances in the field of silent pituitary adenomas were summarized.

EVIDENCE SYNTHESIS

The clinical and biochemical picture of pituitary adenomas reflects a continuum between functional and silent adenomas. Although some adenomas are truly silent, others will show some evidence of biochemical hypersecretion or could have subtle clinical signs and, therefore, can be referred to as clinically silent or "whispering" adenomas. Silent tumors seem to be more aggressive than their secreting counterparts, with a greater recurrence rate. Transcription factors for pituitary cell lineages have been introduced into the 2017 World Health Organization guidelines: steroidogenic factor 1 staining for gonadotroph lineage; PIT1 (pituitary-specific positive transcription factor 1) for growth hormone, prolactin, and TSH lineage, and TPIT for the corticotroph lineage. Prospective studies applying these criteria will establish the value of the new classification.

CONCLUSIONS

A concise review of the clinical and pathological aspects of silent pituitary adenomas was conducted in view of the new World Health Organization classification of pituitary adenomas. New classifications, novel prognostics markers, and emerging imaging and therapeutic approaches need to be evaluated to better serve this unique group of patients.

Successful management of octreotide-insensitive thyrotropin-secreting pituitary adenoma with bromocriptine and surgery: A case report and literature review

RATIONALE

Case reports concerning the value of dopamine agonists in the treatment of patients with thyrotropin-secreting pituitary adenoma (TSHoma) are limited. Herein, we present a rare case of octreotide-insensitive TSHoma responding to bromocriptine therapy.

PATIENT CONCERNS

A 45-year-old Chinese man was admitted to Peking Union Medical College Hospital with marked clinical manifestations of hyperthyroidism.

DIAGNOSES

Thyroid function tests demonstrated elevated concentrations of free thyroid hormones in the presence of normal thyrotropin. Magnetic resonance imaging findings showed a pituitary microadenoma on the right side of the sellar region. Based on characteristic endocrine results and neuroimaging findings, the patient was diagnosed with TSHoma.

INTERVENTIONS

Most patients with TSHomas are significantly responsive to somatostatin analog treatment. However, our patient was orally administered with bromocriptine to normalize thyroid function as assessed by suppression tests conducted prior to surgery. A transsphenoidal surgery was performed by an experienced neurosurgeon for tumor removal.

OUTCOMES

The pituitary lesion was totally resected. Following the operation, the results of thyroid function tests were immediately within reference limits. During the follow-up, there was no residual or recurrent tumor.

LESSONS

Attention should be paid to the role of dopamine agonists such as bromocriptine and cabergoline as adjuvant therapy for TSHomas that are insensitive to traditional medical treatment by somatostatin analogs.