A 28-year-old man presents with progressive visual field defects and headaches. MRI reveals a sellar mass with suprasellar extension, T1 hypointense, T1 post-gadolinium showing homogeneous enhancement, and a cystic component. What is the most common sellar/suprasellar tumor in adults?

Explanation

## Most Common Sellar/Suprasellar Tumor in Adults **Key Point:** Pituitary adenoma is the most common sellar tumor in adults, accounting for approximately 40% of all intracranial tumors and 90% of sellar masses in the adult population. ### Epidemiology and Distribution | Tumor | Frequency in Adults | Peak Age | Key Feature | | --- | --- | --- | --- | | **Pituitary adenoma** | 90% of sellar masses | 40–60 years | Homogeneous enhancement | | **Craniopharyngioma** | 5–10% of sellar masses | Bimodal: 5–14 and 50–74 | Cystic + calcification | | **Meningioma** | Rare sellar | 50–70 years | Dural tail, hyperostosis | | **Optic nerve glioma** | Rare sellar | Childhood | Fusiform, along nerve | ### Imaging Characteristics of Pituitary Adenoma **High-Yield:** Classic MRI features: - **T1 pre-contrast:** Hypointense or isointense (relative to pituitary) - **T1 post-gadolinium:** Homogeneous or heterogeneous enhancement (usually faster than normal pituitary) - **T2:** Variable signal - **Location:** Intrasellar ± suprasellar extension - **Cystic component:** Present in ~20% of cases ### Clinical Presentation **Clinical Pearl:** Visual field defects (bitemporal hemianopsia) occur when suprasellar extension compresses the optic chiasm. Headaches are common due to mass effect or apoplexy. ```mermaid flowchart TD A[Sellar/Suprasellar Mass]:::outcome --> B{Age group?}:::decision B -->|Child| C[Craniopharyngioma]:::action B -->|Adult| D[Pituitary adenoma - 90%]:::action D --> E[Homogeneous enhancement]:::outcome D --> F[Endocrine symptoms or mass effect]:::outcome C --> G[Cystic + calcification]:::outcome ``` **Mnemonic: Pituitary Adenoma vs Craniopharyngioma — "PACE"** - **P**ituitary adenoma: **A**dult, **C**ontiguous with sella, **E**nhances homogeneously - **C**raniopharyngioma: **C**hildhood, **C**ystic + **C**alcification, **E**nhances heterogeneously ### Why Pituitary Adenoma Is Most Common 1. **Prevalence:** Autopsy studies show clinically silent adenomas in ~10% of the general population 2. **Age:** Adults are more commonly affected than children 3. **Hormonal activity:** Many present with endocrine symptoms (prolactin, ACTH, GH excess) 4. **Imaging accessibility:** Widespread MRI use has increased detection [cite:Osborn's Brain Imaging, Pathology, and Anatomy 2e Ch 9]