Dopamine and Tumorigenesis in Reproductive Tissues
Nira Ben-Jonathan in Dopamine, 2020
In view of these conflicting findings, an integrated hypothesis that reconciles the two theories has emerged. It stipulates an occurrence of a certain genomic alteration (the identity of which is unknown) that transforms a single lactotroph as the initial step. The transformed cell escapes normal cell cycle regulation and starts proliferating in response to local growth factors that are abundant in the pituitary, e.g., fibroblast growth factor (FGF), epidermal growth factor (EGF), transforming growth factor alpha (TGFα), or TGFβ. Because transformed cells proliferate faster than normal cells, they are at an increased risk of additional genetic alterations, further promoting tumor progression. Among these could be loss of responsiveness to DA due to mutations in the D2R or its signaling pathways. Although some reduction in D2R expression and receptor density has been reported in prolactinomas, this applies only to the 10%–15% of those tumors that are resistant to bromocriptine therapy and does not offer a universal mechanism that explains the pathogenesis of prolactinomas. It is also important to emphasize that micro-prolactinomas grow very slowly in most patients and do not normally progress to become macroprolactinomas. In fact, the risk of progressing from a microadenoma to a macroadenoma is estimated to be no more than 4%–7% [18]. This suggests that aggressive macroadenoma represent a different and distinct entity, indicating a different etiology of the two types of tumors.
Surgical management of pituitary adenomas
Philip E. Harris, Pierre-Marc G. Bouloux in Endocrinology in Clinical Practice, 2014
Currently, the optimal primary therapy for Cushing’s disease is surgical resection of the pituitary tumor. Postoperative remission rates have been reported in 70%–93% of patients. Remission rates are higher in microadenomas (82%–93%) than in macroadenomas (40%–86%). Tumor recurrence has been detected in up to 26% of cases with long-term (20 year) follow-up.17,18 Favorable factors predicting remission include the identification of a microadenoma on MRI.19,20 Negative pathological findings for ACTH immunore-activity were associated with a 66% remission rate.21 Baseline serum cortisol and ACTH levels do not predict surgical outcomes.22 Macroadenomas are more likely to invade the cavernous sinus and are more difficult to cure surgically.23,24
Reporting session
Deepak Subedi, Marialena Gregoriades, En Hsun Choi, John T Murchison, Graham McKillop in A Complete Guide to the Final FRCR 2B, 2011
Differential enhancement of the pituitary gland relative to pituitary microadenoma (<10 mm) aids detection of microadenomas on dynamic contrast-enhanced MRI or CT. The greatest contrast between normally enhancing gland and hypo-enhancing adenoma is best observed in the first minute post-contrast images. In delayed scan, microadenoma may be hyperintense relative to the rest of the gland. Contrast also helps to assess cavernous sinus invasion, with lack of immediate enhancement indicating invasion. ACTH-secreting pituitary adenomas are the smallest of all pituitary adenomas.
Spontaneous preoperative pituitary adenoma resolution following apoplexy: a case presentation and literature review
Published in British Journal of Neurosurgery, 2020
Daniel G. Eichberg, Long Di, Ashish H. Shah, William A. Kaye, Ricardo J. Komotar
Twelve patients were diagnosed to have macroadenomas and one patient was diagnosed with a microadenoma. All tumors were non-hormone secreting. Six out of 13 patients (46%) showed signs of intrasellar hemorrhage on MRI and five showed compression of the optic nerve. Seven patients (54%) showed decrease concentrations of pituitary hormones on endocrine panels. Although some patients were administered analgesics for symptom relief or placed on hormone replacement therapy, none of the patients underwent surgical intervention. However, all tumors either regressed in size or completely resolved spontaneously. Eight cases (62%) resulted in complete resolution with remission of symptoms, three cases (23%) resulted in panhypopituitarism secondary to empty sella syndrome, one case resulted in a tumor that regressed in size but was still visible on MRI, and one case – the current presented case – resulted in complete spontaneous resolution, but subsequent regrowth of the tumor four years later. Twelve cases have attributed the spontaneous resolution of the tumor to necrosis following apoplexy, while the authors of one case hypothesized a viral etiology which was not explained further. Table 2 is a statistical summary and analysis of the data collected in Table 1.
Peripheral clock system circadian abnormalities in Cushing’s disease
Published in Chronobiology International, 2020
Vinicius Reis Soares, Clarissa Silva Martins, Edson Zangiacomi Martinez, Leonardo Domingues Araujo, Silvia Liliana Ruiz Roa, Lucas Ravagnani Silva, Ayrton Custodio Moreira, Margaret De Castro
All CD patients presented ACTH-dependent Cushing syndrome, with high (n = 11) or normal (n = 1) ACTH levels (16.4 ± 6.5 pmol/L; normal range: 2.2–11 pmol/L). All patients underwent MRI, 8 out of 12 patients presented microadenoma, 3 out of 12 macroadenoma, and one showed no visible pituitary tumor. All patients, except one, presented an ACTH and/or cortisol response after DDAVP (ACTH increment of 191.8 ± 254.4% and cortisol increment of 60.9 ± 37.4%). Six out of 12 patients underwent BIPSS due to small tumors or no evidence of pituitary tumor on MRI or discordant response to DDAVP test. All of them showed central/peripheral gradient, confirming the pituitary disease. Eleven CD patients were submitted to transsphenoidal surgery and six of them are in remission of disease (54.5%), five are under treatment with ketoconazole or ketoconazole and radiotherapy. Patient 10 was last evaluated in 2019 and has been followed with no transsphenoidal surgery so far.
Characteristics and outcome of surgically treated acromegaly patients attending an endocrinology clinic at a tertiary referral centre in Durban, South Africa over a period of 10 years
Published in Journal of Endocrinology, Metabolism and Diabetes of South Africa, 2018
Abdurraouf Masaud Elbueishi, Fraser J Pirie, Ayesha A Motala
MRI was performed in 23 (85.1%) of the patients and 4 (14.9%) had pituitary CT scan. A pituitary adenoma was identified in 27 (100%) patients; of these, pituitary macroadenoma was found in 92.5% (n = 25) subjects. Precise measurement of the maximal tumour size was reported in 22 (81.4%) patients. Where the tumour size was available, the mean (± SD) was 3.0 ± 0.75 cm. Of the 25 patients with a pituitary macroadenoma, 18 (72%) demonstrated extension beyond the confines of the sella, with optic chiasm compression occurring in all these 18 patients; extension into the cavernous sinus was reported in 12 of these 18 patients. Pituitary microadenoma was diagnosed in 2 (7.4%) patients. No patients were diagnosed with ectopic GH-secreting or GHRH-secreting tumours.
Related Knowledge Centers
- Benign Tumor
- Prevalence
- Neoplasm
- Pituitary Gland
- Meta-Analysis
- Autopsy
- Medical Imaging
- Incidental Medical Findings
- Incidental Imaging Finding
- Hypopituitarism