Ectopic Adrenocorticotropic Hormone–Secreting Pituitary Adenoma Localized by 18F-Choline PET/CT

Clival Ectopic Pituitary Adenoma Causing Cushing Syndrome

The development of adenohypophysis by differentiating and detaching from the pharyngeal roof results in formation of a functional ectopic pituitary tissue around the Sella turcica. Of the ectopic sites in which pituitary adenoma occurs, clival adenomas are rare and the majority secrete prolactin. We report a case of ACTH-dependent Cushing syndrome. Magnetic resonance imaging revealed a clival mass with sphenoid sinus infiltration and 68Gallium (Ga) Dodecane tetra acetic acid-NaI3-octreotide positron emission tomography-computed tomography showed intense uptake in the region. Postoperative immunohistochemistry revealed ACTH and T-box Protein in T-cell positivity. With literature review, we found 5 reported cases of clival ectopic pituitary adenoma with Cushing syndrome. Clinical characteristics, imaging features, histology, and management of such masses have been discussed. In conclusion, ACTH-producing clival ectopic pituitary adenomas are rare, require differentiation from neuroendocrine tumors, and remit by multimodal therapy.

The utility of PET for detecting corticotropinomas in Cushing disease: a scoping review

While magnetic resonance imaging (MRI) is the current standard imaging method for diagnosing and localizing corticotropinomas in Cushing disease, it can fail to detect adenomas in up to 40% of cases. Recently, positron emission tomography (PET) has shown promise as a diagnostic tool to detect pituitary adenomas in Cushing disease. We perform a scoping review to characterize the uses of PET in diagnosing Cushing disease, with a focus on describing the types of PET investigated and defining PET-positive disease. A scoping review was conducted following the PRISMA-ScR guidelines. Thirty-one studies fulfilled our inclusion criteria, consisting of 10 prospective studies, 8 retrospective studies, 11 case reports, and 2 illustrative cases with a total of 262 patients identified. The most commonly utilized PET modalities in prospective/retrospective studies were FDG PET (n = 5), MET PET (n = 5), 68 Ga-DOTATATE PET (n = 2), 13N-ammonia PET (n = 2), and 68 Ga-DOTA-CRH PET (n = 2). MRI positivity ranged from 13 to 100%, while PET positivity ranged from 36 to 100%. In MRI-negative disease, PET positivity ranged from 0 to 100%. Five studies reported the sensitivity and specificity of PET, which ranged from 36 to 100% and 50 to 100%, respectively. PET shows promise in detecting corticotropinomas in Cushing disease, including MRI-negative disease. MET PET has been highly investigated and has demonstrated excellent sensitivity and specificity. However, preliminary studies with FET PET and 68 Ga-DOTA-CRH PET show promise for achieving high sensitivity and specificity and warrant further investigation.

Clinical and radiological presentation of parasellar ectopic pituitary adenomas: case series and systematic review of the literature

PURPOSE

Parasellar ectopic pituitary adenomas (pEPAs) are extremely rare tumors located out of the sella turcica. PEPAs are heterogeneous entities in terms of anatomical localization and secretion of anterior pituitary hormones.

METHODS

Multicenter retrospective study. Clinical charts' consultation of patients diagnosed with parasellar lesions, to identify all subjects fulfilling the diagnostic criteria of parasellar EPAs. Systematic review of the literature focused on the medical management of prolactin-secreting pEPAs and on the prevalence of radiological bone invasion in pEPAs.

RESULTS

We identified four cases of pEPAs: (1) 54-year-old female with a prolactin-secreting suprasellar EPA successfully treated with cabergoline; (2) 74-year-old male with a non-functioning EPA of the sphenoidal sinus treated with endoscopic transsphenoidal surgery; (3) 75-year-old female with a giant lesion of the skull base (maximum diameter 7.2 cm) diagnosed as a non-functioning EPA after biopsy; (4) 49-year-old male with a silent corticotroph EPA of the sphenoidal sinus and clivus. Three out of four cases had radiological evidence of invasion of the surrounding bone structures. A systematic review of the literature highlighted that medical therapy can be effective in prolactin-secreting pEPAs. Overall, we found mention of local invasiveness in 65/147 cases (44.2%), confirmed by radiological signs of bone invasion/erosion.

CONCLUSION

Our experience confirms the heterogeneity of pEPAs in terms of clinical and radiological presentation, as well as hormone secretion. PEPAs show a high frequency of radiological bone invasion, though similar to that of sellar pituitary adenomas. Although extremely rare, pEPAs need to be considered in the differential diagnosis of parasellar lesions.

Ectopic pituitary adenomas: clinical features, diagnostic challenges and management

PURPOSE

Ectopic pituitary adenomas (EPAs) are extremely rare pituitary adenomas located outside the sella turcica without any connection with intrasellar components. This study aims to review all the reported cases to date and describe the clinical characteristics of EPAs.

METHODS

In a retrospective chart review, 14 patients were identified with EPAs in our hospital. A literature review was performed, and 166 cases in the literature met the criteria. Clinical data were analyzed.

RESULTS

Of 180 patients with EPAs, the mean age at diagnosis was 45.4 years, and 66.5% of the patients were females. EPAs were mainly located in the sphenoid sinus (34.4%) and suprasellar region (25.6%), followed by the clivus (15.6%), cavernous sinus (13.3%) and nasopharynx (5.6%). Adrenocorticotropic hormone (ACTH)-secreting (38.9%) and nonfunctioning (27.2%) adenomas were predominant. Patients with suprasellar EPAs were more likely to present menstrual disorders and visual changes, while patients with clival EPAs were more likely to suffer from headaches. EPAs in the cavernous sinus and suprasellar space were more likely to be initially misdiagnosed as a suspicious intrasellar mass on imaging examination. The complete tumor resection rates for EPAs in the sphenoid sinus, suprasellar region, clivus, cavernous sinus and nasopharynx were 72.3%, 88.6%, 45.0%, 73.3% and 88.9%, respectively.

CONCLUSIONS

EPA clinical characteristics varied across different tumor locations and hormone-secreting types. In addition to comprehensive hormone evaluation and careful review of imaging data, nuclear medicine and surgical biopsy should also be considered when facing differential difficulty. EPA management should be individualized.

Long-term follow-up for ectopic ACTH-secreting pituitary adenoma in a single tertiary medical center and a literature review

BACKGROUND

Ectopic ACTH-secreting pituitary adenoma (EAPA) are a rare cause of Cushing's disease. Due to the lack of consensus and experience in terms of the diagnosis and treatment of EAPAs, preoperative identification and optimal treatment remain challenging.

PURPOSE

To investigate the characteristics of EAPAs and offer some proposals for the diagnosis and management of this uncommon disease, the EAPA patients admitted to our center and all of the EAPA cases reported in the literature were reviewed.

METHODS

In a retrospective electronic medical chart review, 6 patients (0.39%) with EAPAs were identified from 1536 consecutive patients who were admitted to our hospital with a diagnosis of Cushing's syndrome between January 2000 and August 2019. A literature review was performed on the online databases PubMed and EMBASE, and 52 cases conformed to the criteria. The data regarding biochemical tests, imaging examinations and follow-ups were analyzed.

RESULTS

The mean age of patients with EAPAs was 37.7 years old, and an obvious female predominance (3.5: 1) was demonstrated. The most common location of EAPAs was the cavernous sinus (34.5%), followed by the sphenoid sinus (31.0%) and the suprasellar region (20.7%). No significant differences in the biochemical test results were found among tumors in different locations. Except for sex, no risk factors related to remission were found. Although no significant differences among different locations were found, the tumors in the cavernous sinus had a relatively higher rate of invisibility in terms of imaging and a higher non-remission rate than tumors in other locations.

CONCLUSIONS

In patients with negative intrasellar findings, the uncommon disease of EAPA should be considered. Due to the endocrine similarity between intrasellar pituitary corticotrophin adenoma and EAPA, the preoperative identification of EAPA depends on a careful review of the imaging examinations. Locations such as the cavernous sinus, sphenoid sinus and suprasellar region should be considered first. Tumor resection is recommended when the diagnosis is confirmed.

FDG PET/CT Findings of Ectopic Pituitary Adenoma

A 72-year-old woman had undergone a right mastectomy for breast cancer 3 years earlier. PET/CT revealed a tumor with bony destruction of the skull base and FDG accumulation (SUVmax, 7.86). MRI showed the well-circumscribed tumor in the sphenoid sinus. The possibility of bone metastasis could not be denied. Tumor removal surgery was performed; the tumor was separate from the normal pituitary gland, and an ACTH-producing ectopic pituitary adenoma was diagnosed pathologically.

The pituitary in nuclear medicine imaging

The pituitary is an endocrine gland with ability to uptake diverse radiopharmaceuticals and, therefore, susceptible to be investigated by nuclear medicine diagnostic procedures. Although this topic has been scarcely scrutinized, we have data indicating that somatostatin receptor scintigraphy with¹¹¹In-DTPA-D-Phe-octreotide or ^99mTc-EDDA/HYNIC-TOC may be of clinical utility in the diagnosis of some pituitary adenomas (PA). Only a few studies have evaluated the diagnostic performance of ^99mTc-MIBI and ^99mTc (V)-DMSA scintigraphy in pituitary disease. Scintigraphy using ¹²³I-methoxybenzamide (¹²³I-IBZM) might be useful in macroprolactinomas expressing dopamine D2 receptors. Pituitary gland does not usually accumulate 2-deoxy-2-[¹⁸F]fluoro-d-glucose (¹⁸F-FDG) and, therefore, it is not visualized on positron emission tomography (PET) imaging studies with this radiotracer. The pituitary uptake on¹⁸F-FDG PET/CT scans performed in the follow-up of oncological patients are uncommon. However, 60% of these incidental findings are due to PA, mainly non-functioning pituitary macroadenomas, and a small percentage to metastases or other pituitary lesions. Interestingly, ¹⁸F-FDG PET/CT may identify hypophysitis induced by different immunotherapeutic agents used in cancer patients. Positive ¹⁸F-FDG uptake has been reported in a high percentage of patients with PA, mainly macroadenomas and it seems that there is correlation between tumor size and SUVmax. ⁶⁸Ga-DOTA-TATE PET/CT may identify functioning and non-functioning PA, although this technique is more useful in the detection of remaining normal pituitary tissue after transsphenoidal adenomectomy, and in the confirmation of recurrence of functioning PA, such as thyrotroph-secreting PA. Furthermore, ⁶⁸Ga-DOTA-TATE uptake has potential therapeutic implications on molecular-targeted therapy. Lastly, other radiopharmaceuticals that have shown to be taken up in some patients with pituitary disease include ¹⁸F-DOPA (prolactinoma), ¹¹C-methionine (residual or recurrent PA), O-(2-¹⁸F-fluoroethyl)-l-tyrosine (metastasis), ¹⁸F-choline (silent adenoma, ectopic corticotropinoma), and ¹³N-ammonia (hypopituitarism).

Variability in Clinical Presentation and Pathologic Implications of Ectopic Pituitary Tumors: Critical Review of Literature

OBJECTIVE

Pituitary tumors are common, well-described skull base tumors of sellar origin. However, there are reports of rare ectopic pituitary tumors that are found exclusively outside of the sella turcica. Ectopic pituitary tumors have not been holistically analyzed. This study describes presentation and clinical patterns found among patients with ectopic pituitary tumors.

METHODS

A comprehensive review of the literature was performed for clinical descriptions of ectopic pituitary tumors. Reports of 85 applicable cases were evaluated.

RESULTS

The most common locations of ectopic pituitary tumors were the sphenoid sinus, clivus, suprasellar space, nasopharynx, and cavernous sinus. The majority of ectopic pituitary tumors were reported as being functional secretory tumors; they were statistically significantly more likely to be functional tumors than sellar pituitary tumors. Adrenocorticotrophic hormone, prolactin, growth hormone, and thyroid-stimulating hormone-secreting tumors were most commonly found. Bone invasion was reported in more than one third of the cases, and malignant transformations were reported in 6 cases. A large majority of patients presented with hormonal, neurologic, or physiologic symptoms.

CONCLUSIONS

Ectopic pituitary tumors are a rare entity of pituitary tumors with a presentation that can mimic those of other skull base tumors. Clinical presentation often correlates to location of the tumor. Ectopic pituitary tumors were significantly more likely to be functional secretory tumors. They may also exhibit more aggressive behavior than sellar-located tumors. Ectopic pituitary tumors may be part of a spectrum of presenting pathologies. Further genetic or genomic analysis is necessary to better understand their pathogenesis and clinical presentations.

[Ectopia of the pituitary]

The adenohypophysis has a large intrasellar part and two small parts at the pituitary stalk and the pharynx. Near this extrasellar pituitary tissue, and also in sinus sphenoidalis and sinus cavernosus, ectopic pituitary adenomas can develop. They are indistinguishable in structure and function from usual intrasellar adenomas. The neurohypophysis can show dystopias within complex malformations. In so-called pituitary stalk interruption syndrome, a real ectopia of the neurohypophysis is found at the eminentia mediana of the hypothalamus. Ectopic tissue in the pituitary is extremely rare: foci of ganglionic cells were found in the neurohypophysis and adrenocortical tissue in the adenohypophysis. Focal squamous epithelia in the anterior pituitary are a common finding but they are rather metaplastic from parenchymal cells than ectopic tissue. Small foci of ectopic salivary gland tissue are not rare in the intermediate zone.