On this page
Several labels can appear in the same report because they answer different questions. “Macroadenoma” describes size. “Prolactinoma” describes a hormone-secreting subtype. “Incidentaloma” describes discovery. “PitNET” reflects a classification term. None supplies the whole clinical picture on its own.
Functioning and nonfunctioning
A clinically functioning adenoma produces hormone excess that causes a clinical syndrome. A clinically nonfunctioning adenoma does not cause an evident hormone-excess syndrome. Nonfunctioning does not mean that normal pituitary function is guaranteed: a mass may interfere with it, or have local effects. Hormone excess and hormone deficiency are separate assessment questions.12
Pathological classification, when tissue is available, considers the cells and their hormone/lineage markers. A pathological label and the clinical hormone syndrome are related, but are not interchangeable. In particular, “silent” or nonfunctioning does not mean that the tissue has no pituitary lineage.3
Common hormone-related descriptions
| Description | What it refers to |
|---|---|
| Prolactinoma | An adenoma secreting prolactin. The evaluation separates this from other reasons for an elevated prolactin result. |
| Growth hormone–secreting adenoma | Excess growth hormone can cause acromegaly in adults; assessment also uses its downstream hormone signal, IGF-1. |
| ACTH-secreting adenoma | Pituitary ACTH can drive excess adrenal cortisol, causing Cushing disease. Cushing syndrome has other possible causes. |
| TSH-secreting adenoma | A rare cause of inappropriate thyroid stimulation; specialist endocrine evaluation is needed. |
| Clinically nonfunctioning adenoma | No evident hormone-excess syndrome. Care focuses on the lesion’s behavior, anatomy and pituitary function. |
The hormone names describe pathways rather than an at-home diagnostic checklist. NCI’s overview introduces their roles; the incidentaloma and prolactinoma guidance adds clinical assessment context.124
Size and nearby anatomy
The usual size division is microadenoma below 10 mm and macroadenoma at least 10 mm. These categories help describe an image; they do not tell you whether a hormone syndrome is present. Relationship to the optic chiasm, extension and change across earlier scans add information that a single diameter misses. A small functioning lesion and a larger nonfunctioning lesion can lead to very different conversations.2
Ask which imaging features actually affect your team’s recommendation. A report may use terms concerning surrounding structures that need explanation by the interpreting specialist. Do not translate a size category into a prognosis or decide that “small” means harmless.
Adenoma, PitNET and cancer
The WHO 2022 classification uses PitNET/adenoma terminology. A professional workshop perspective describes the concerns around treating that terminology as a prognosis. Most adenomas do not behave as metastatic malignancies. Local extension or invasion, a neuroendocrine name and metastatic disease are different concepts; specialist interpretation of clinical behavior and pathology matters.3
Young age, family history, pregnancy and childhood can require a different assessment. General adult explanations should not become a substitute for those specific pathways.
References
- National Cancer Institute. What Are Pituitary Tumors? Updated 28 March 2025. Source ↩
- Fleseriu M et al. Nat Rev Endocrinol. 2025;21:638–655. Published 24 June 2025. doi:10.1038/s41574-025-01134-8. Source ↩
- Ho KKY et al. Nat Rev Endocrinol. 2023. Published 17 August 2023. doi:10.1038/s41574-023-00883-8. Source ↩
- Petersenn S et al. Nat Rev Endocrinol. 2023;19:722–740. doi:10.1038/s41574-023-00886-5. Read with Author Correction, 17 October 2023. Source ↩