Lowest incidence of cerebral tumours is seen in –
**Core Concept**
Cerebral tumors are abnormal growths of cells in the brain, which can be benign or malignant. They can arise from various cell types, including astrocytes, neurons, and oligodendrocytes. The incidence of cerebral tumors varies depending on age, ethnicity, and geographical location.
**Why the Correct Answer is Right**
The correct answer is **Meningioma**. Meningiomas are tumors that arise from the meninges, the protective layers surrounding the brain and spinal cord. They are typically slow-growing, benign tumors that account for approximately 25-30% of all primary brain tumors. The incidence of meningiomas is relatively low compared to other types of cerebral tumors, such as gliomas or pituitary adenomas.
**Why Each Wrong Option is Incorrect**
* **Option A:** Glioblastoma - Glioblastomas are the most aggressive and common type of primary brain tumor, accounting for approximately 50-60% of all gliomas. They have a higher incidence compared to meningiomas.
* **Option B:** Pituitary Adenoma - Pituitary adenomas are benign tumors that arise from the pituitary gland and account for approximately 10-15% of all primary brain tumors. Their incidence is higher than that of meningiomas.
* **Option C:** Medulloblastoma - Medulloblastomas are malignant tumors that arise from the cerebellum and account for approximately 20-25% of all brain tumors in children. Their incidence is lower in adults and not as low as meningiomas.
**Clinical Pearl / High-Yield Fact**
Meningiomas are often asymptomatic until they reach a large size, and their diagnosis may be delayed. A high index of suspicion is necessary when evaluating patients with non-specific symptoms such as headache, seizures, or cognitive decline.
**Correct Answer: D. Meningioma**