An Update on Pituitary Neuroendocrine Tumors Leading to Acromegaly and Gigantism

Complete Shrinking of Mixed Growth Hormone and Prolactin-Secreting Pituitary Adenoma With Bromocriptine Therapy Alone

A 40-year-old man presented with acromegaly, reduction of visual acuity and visual field, and elevated blood sugar. Imaging examinations demonstrated a large sellar adenoma with suprasellar extension that compresses the optic chiasma upward, spreads downward to the sphenoid sinus, and invades the cavernous sinus bilaterally. Random prolactin and growth hormone were beyond the scope of normal. The patient achieved complete shrinking of the adenoma by taking bromocriptine orally. For some kinds of giant mixed growth hormone-prolactin adenomas, surgical treatment is not necessary, and drug treatment can also achieve good results.

Histopathology of growth hormone-secreting pituitary tumors: State of the art and new perspectives

Somatotroph (GH) adenomas/PitNETs typically arise from adenohypophysis and are biochemically active, leading to acromegaly and gigantism. More rarely, they present with ectopic origin and do not present overt biochemical or clinical features (silent variants). Histopathological examination should consider the clinical and radiological background, and include multiple steps assessing tumor morphology, pituitary transcription factors (PTFs), hormone secretion, proliferation markers, granulation, and somatostatin receptors (STRs), aimed at depicting as better as possible tumor origin (in case of non-functioning and/or metastatic tumor), and clinical behavior, including response to treatment. GH-secreting tumors are part of the Pit-1 family tumors and can secrete GH only (pure somatotrophs) or co-secrete prolactin (mixed tumors; in this case, various histological subtypes have been identified). Each subtype presents unique radiological, biochemical, and clinical characteristic. Therefore, the integration of biochemical, clinical, radiological, and histopathological elements is fundamental for proper diagnosis and management of pituitary adenomas/PitNETs, to be performed in referral Centers. In more recent times, the importance of genetic and epigenetic evaluation in the characterization of pituitary tumors (i.e., early identification of aggressive variants) has been outlined by some large studies, with the intention of improving targeted treatments.

The clinical and biochemical spectrum of ectopic acromegaly

Ectopic acromegaly is a rare condition caused by extrapituitary central or peripheral neuroendocrine tumours (NET) that hypersecrete GH or, more commonly, GHRH. It affects less than 1% of acromegaly patients and a misdiagnosis of classic acromegaly can lead to an inappropriate pituitary surgery. Four types of ectopic acromegaly have been described: 1) Central ectopic GH-secretion: Careful cross-sectional imaging is required to exclude ectopic pituitary adenomas. 2) Peripheral GH secretion: Extremely rare. 3) Central ectopic GHRH secretion: Sellar gangliocytomas immunohistochemically positive for GHRH are found after pituitary surgery. 4) Peripheral GHRH secretion: The most common type of ectopic acromegaly is due to peripheral GHRH-secreting NETs. Tumours are large and usually located in the lungs or pancreas. Pituitary hyperplasia resulting from chronic GHRH stimulation is difficult to detect or can be misinterpreted as pituitary adenoma in the MRI. Measurement of serum GHRH levels is a specific and useful diagnostic tool. Surgery of GHRH-secreting NETs is often curative.

The Driver Role of Pathologists in Endocrine Oncology: What Clinicians Seek in Pathology Reports

Endocrine neoplasia represents an increasingly broad spectrum of disorders. Endocrine neoplasms range from incidental findings to potentially lethal malignancies. In this paper, we cover the impact of pathology in the interpretation of the clinic-pathological, genetic, and radiographic features underpinning these neoplasms. We highlight the critical role of multidisciplinary interactions in structuring a rational diagnostic and efficient therapeutic plan and emphasize the role of histopathological input in decision-making. In this context, standardized pathology reporting and second opinion endocrine pathology review represent relevant tools to improve the overall diagnostic workup of patients affected by endocrine tumors in every specific scenario. In fact, although a relevant proportion of cases may be correctly identified based on clinical presentation and biochemical/imaging investigations, a subset of cases presents with atypical findings that may lead to an inappropriate diagnosis and treatment plan based on a wrong pathological diagnosis if all pieces of the puzzle are not correctly considered. Pathologists have a responsibility to actively guide clinicians before and during surgical procedures to prevent unnecessary interventions. In all areas of endocrine pathology, pathologists must understand the complexity of tissue preservation and assay sensitivities and specificities to ensure the optimal quality and interpretation of diagnostic material. Finally, pathologists are central actors in tumor tissue biobanking, which is an expanding field in oncology that should be promoted while adhering to strict ethical and methodological standards.

Neoplasms and tumor-like lesions of the sellar region: imaging findings with correlation to pathology and 2021 WHO classification

The sellar region represents a complex anatomical area, composed of multiple structures of different embryological derivation, including the skull base and the pituitary gland, along with vascular, nervous, and meningeal structures. Masses arising in this region include benign and malignant lesions arising from the pituitary gland itself, but also from vestigial embryological residues or surrounding tissues, that may require different therapeutic approaches. While assessing sellar region masses, the combination of clinical presentation and imaging features is fundamental to define hypotheses about their nature. MR represents the imaging modality of choice, providing information about the site of the lesion, its imaging features, and relation with adjacent structures, while CT is useful to confirm the presence of lesion calcifications or to reveal tumor invasion of bony structures. The aim of this pictorial review is to provide an overview of the common neoplasms and tumor-like conditions of the sellar region, according to the 2021 WHO Classification of Tumors of the Central Nervous System (fifth edition), with an emphasis on the radiologic-pathologic correlation. After a brief introduction on the anatomy of this region and the imaging and pathological techniques currently used, the most relevant MRI characteristics, clinical findings, and pathological data, including histologic and molecular features, will be shown and discussed, with the aim of facilitating an appropriate differential diagnosis among these entities.

The Spectrum of Familial Pituitary Neuroendocrine Tumors

Hereditary pituitary tumorigenesis is seen in a relatively small proportion (around 5%) of patients with pituitary neuroendocrine tumors (PitNETs). The aim of the current review is to describe the main clinical and molecular features of such pituitary tumors associated with hereditary or familial characteristics, many of which have now been genetically identified. The genetic patterns of inheritance are classified into isolated familial PitNETs and the syndromic tumors. In general, the established genetic causes of familial tumorigenesis tend to present at a younger age, often pursue a more aggressive course, and are more frequently associated with growth hormone hypersecretion compared to sporadic tumors. The mostly studied molecular pathways implicated are the protein kinase A and phosphatidyl-inositol pathways, which are in the main related to mutations in the syndromes of familial isolated pituitary adenoma (FIPA), Carney complex syndrome, and X-linked acrogigantism. Another well-documented mechanism consists of the regulation of p27 or p21 proteins, with further acceleration of the pituitary cell cycle through the check points G1/S and M/G1, mostly documented in multiple endocrine neoplasia type 4. In conclusion, PitNETs may occur in relation to well-established familial germline mutations which may determine the clinical phenotype and the response to treatment, and may require family screening.

An Overview of Pituitary Neuroendocrine Tumors (PitNET) and Algorithmic Approach to Diagnosis

The diagnostic algorithm and nomenclature of pituitary neuroendocrine tumors have evolved over the past decade, beginning with simpler categorical schemes focused on histomorphologic features and moving to a more sophisticated lineage-specific categorization. This contemporary overview highlights a multimodal approach to pituitary neuroendocrine tumors with a focus on changes in nomenclature, classification, and subclassification; including, brief comments on treatment, and new guidelines for genetic screening, particularly for young patients with such neoplasms.

Persistent Orthostatic Hypotension in a Patient With Acromegaly: Resolution With Transsphenoidal Hypophysectomy

Acromegaly is a rare condition characterized by excessive secretion of growth hormone from a pituitary tumor. It can affect multiple systems and can be fatal with cardiac dysfunction being the most common cause of death in these patients. Autonomic dysfunction is a less studied subject in patients with acromegaly, and the exact pathophysiology is still unclear. Here we present a case of a patient with persistent orthostatic hypotension, who was found to have acromegaly and pituitary adenoma upon further evaluation. Her orthostatic symptoms failed to improve with conservative measures and medical management, but unexpectedly resolved after transsphenoidal hypophysectomy was performed.

Overview of the 2022 WHO Classification of Pituitary Tumors

This review summarizes the changes in the 5th Edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the pituitary gland. The new classification clearly distinguishes anterior lobe (adenohypophyseal) from posterior lobe (neurohypophyseal) and hypothalamic tumors. Other tumors arising in the sellar region are also discussed. Anterior lobe tumors include (i) well-differentiated adenohypophyseal tumors that are now classified as pituitary neuroendocrine tumors (PitNETs; formerly known as pituitary adenomas), (ii) pituitary blastoma, and (iii) the two types of craniopharyngioma. The new WHO classification provides detailed histological subtyping of a PitNET based on the tumor cell lineage, cell type, and related characteristics. The routine use of immunohistochemistry for pituitary transcription factors (PIT1, TPIT, SF1, GATA3, and ERα) is endorsed in this classification. The major PIT1, TPIT, and SF1 lineage-defined PitNET types and subtypes feature distinct morphologic, molecular, and clinical differences. The "null cell" tumor, which is a diagnosis of exclusion, is reserved for PitNETs with no evidence of adenohypophyseal lineage differentiation. Unlike the 2017 WHO classification, mammosomatotroph and acidophil stem cell tumors represent distinct PIT1-lineage PitNETs. The diagnostic category of PIT1-positive plurihormonal tumor that was introduced in the 2017 WHO classification is replaced by two clinicopathologically distinct PitNETs: the immature PIT1-lineage tumor (formerly known as silent subtype 3 tumor) and the mature plurihormonal PIT1-lineage tumor. Rare unusual plurihormonal tumors feature multi-lineage differentiation. The importance of recognizing multiple synchronous PitNETs is emphasized to avoid misclassification. The term "metastatic PitNET" is advocated to replace the previous terminology "pituitary carcinoma" in order to avoid confusion with neuroendocrine carcinoma (a poorly differentiated epithelial neuroendocrine neoplasm). Subtypes of PitNETs that are associated with a high risk of adverse biology are emphasized within their cell lineage and cell type as well as based on clinical variables. Posterior lobe tumors, the family of pituicyte tumors, include the traditional pituicytoma, the oncocytic form (spindle cell oncocytoma), the granular cell form (granular cell tumor), and the ependymal type (sellar ependymoma). Although these historical terms are entrenched in the literature, they are nonspecific and confusing, such that oncocytic pituicytoma, granular cell pituicytoma, and ependymal pituicytoma are now proposed as more accurate. Tumors with hypothalamic neuronal differentiation are classified as gangliocytomas or neurocytomas based on large and small cell size, respectively. This classification sets the standard for a high degree of sophistication to allow individualized patient management approaches.

Current and Emerging Medical Therapies in Pituitary Tumors

Pituitary tumors (PT) represent in, the majority of cases, benign tumors for which surgical treatment still remains, except for prolactin-secreting PT, the first-line therapeutic option. Nonetheless, the role played by medical therapies for the management of such tumors, before or after surgery, has evolved considerably, due in part to the recent development of well-tolerated and highly efficient molecules. In this review, our aim was to present a state-of-the-art of the current medical therapies used in the field of PT and the benefits and caveats for each of them, and further specify their positioning in the therapeutic algorithm of each phenotype. Finally, we discuss the future of PT medical therapies, based on the most recent studies published in this field.

Neutrophil-to-Lymphocyte, Platelet-to-Lymphocyte Ratios, and Systemic Immune-Inflammation Index as Potential Biomarkers of Chronic Inflammation in Patients with Newly Diagnosed Acromegaly: A Single-Centre Study

Acromegaly is a rare disease caused by overproduction of growth hormone (GH) by a pituitary adenoma, and consequently increased insulin-like growth factor 1 (IGF-1) concentration. The GH/IGF-1 axis and immune cells interactions are hypothesized to be involved in subclinical inflammation. This retrospective study aimed to investigate the differences in neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR) ratios, and systemic immune-inflammation index (SII) in GH-secreting adenomas compared with non-functioning pituitary adenomas (NFPAs) concerning clinical and radiological findings. After evaluation of 665 patients with pituitary tumors, 62 individuals with newly diagnosed acromegaly and 134 with NFPAs were enrolled in the analysis. The control group consisted of 120 healthy individuals. Fifty-eight patients with acromegaly were re-evaluated after medical or surgical therapies. NLR, PLR, SII values, and neutrophil count were significantly higher (p ≤ 0.001), whereas lymphocyte count was lower in acromegaly than in NFPAs (p = 0.001). No significant differences between NFPAs and controls were observed in analyzed ratios. Higher preoperative NLR, PLR, SII values were found in patients who failed to achieve a cure with surgery (p < 0.05). Although NLR, PLR, and SII values were significantly higher in acromegaly, these indices cannot be used to discriminate GH-secreting pituitary tumors from NFPAs. Treatment of acromegaly decreased the value of NLR and SII, but it requires further studies to consolidate the real clinical role of these inflammation-related ratios.