A 35-year-old male presents with complaint of recurrent headaches. On further investigation, the following MRI was received. What is the most likely diagnosis?

Explanation

## Correct Answer: D. Meningioma Meningiomas are the most common intracranial extraaxial tumors in adults, arising from the dura mater. The classic imaging hallmark is a **dural tail sign**—enhancement of the dura extending beyond the tumor margin—which is highly specific for meningioma. On MRI, meningiomas typically appear as well-demarcated, broad-based lesions with homogeneous enhancement on contrast-enhanced T1-weighted images. They are usually hypointense or isointense on T2-weighted sequences. The tumor shows a clear interface with brain parenchyma, indicating extraaxial origin. In a 35-year-old presenting with recurrent headaches, meningioma is the most likely diagnosis when imaging shows these characteristic features: extraaxial location, dural attachment, dural tail sign, and homogeneous enhancement. Meningiomas account for approximately 30% of all intracranial tumors in India, with peak incidence in the 4th–6th decade. The recurrent headaches are explained by mass effect and increased intracranial pressure. Definitive diagnosis requires histopathology, but imaging findings are highly suggestive. Treatment involves surgical resection when symptomatic, as in this case. ## Why the other options are wrong **A. Pilocystic astrocytoma** — Pilocystic astrocytomas are intraaxial tumors (within brain parenchyma), typically arising in the cerebellum or optic pathway in children and young adults. They appear as cystic lesions with a mural nodule on MRI, not as a well-demarcated extraaxial mass with dural tail. The imaging pattern described—extraaxial location with dural enhancement—is incompatible with pilocystic astrocytoma. **B. Glioma** — Gliomas (including high-grade glioblastomas and low-grade astrocytomas) are intraaxial tumors that infiltrate brain parenchyma, showing ill-defined margins and heterogeneous enhancement with surrounding edema. They lack the characteristic dural tail sign and broad dural base seen in meningiomas. The well-demarcated, extraaxial appearance rules out glioma. **C. Medulloblastoma** — Medulloblastomas are highly aggressive intraaxial tumors arising in the posterior fossa (cerebellum) in children, rarely in adults. They present with hydrocephalus and show heterogeneous enhancement with restricted diffusion. The patient's age (35 years) and imaging pattern of an extraaxial mass with dural attachment are atypical for medulloblastoma, which typically occurs in the pediatric population. ## High-Yield Facts - **Dural tail sign** is highly specific for meningioma—enhancement of dura extending beyond tumor margin on contrast-enhanced MRI. - Meningiomas are **extraaxial tumors** with broad dural base, unlike intraaxial gliomas which infiltrate brain parenchyma. - **Peak incidence** of meningiomas is 4th–6th decade; they are the most common intracranial extraaxial tumor in adults. - **T2 signal** in meningiomas is typically hypointense or isointense (unlike edematous gliomas), aiding differentiation. - **Homogeneous enhancement** on contrast-enhanced T1 is characteristic; heterogeneous enhancement suggests glioma or other intraaxial lesion. - Meningiomas account for **~30% of all intracranial tumors** in India; surgical resection is the DOC for symptomatic lesions. ## Mnemonics **DURAL TAIL = MEningioma** **D**ural tail sign, **U**nder dura (extraaxial), **R**ound/broad base, **A**dult age, **L** = **M**eningioma. Dural tail is pathognomonic. **ExtraAxial vs IntraAxial** **MEningioma** = **E**xtraaxial (outside brain), **G**lioma = **I**ntraaxial (inside brain). Meningioma has dural attachment; glioma infiltrates parenchyma. ## NBE Trap NBE may pair "recurrent headaches" with intraaxial tumors (glioma, medulloblastoma) to trap students who focus on symptom rather than imaging findings. The key discriminator is the **extraaxial location and dural tail sign**, not the presenting complaint. ## Clinical Pearl In Indian clinical practice, meningiomas presenting with recurrent headaches and focal neurological deficits are managed surgically when imaging is characteristic. The dural tail sign on MRI is so specific that it often allows confident preoperative diagnosis without biopsy, expediting surgical planning in resource-limited settings. _Reference: Robbins Ch. 28 (CNS Neoplasms); Harrison Ch. 375 (Neuro-oncology)_