**Core Concept**
Extramedullary tumours are a type of cancer that arise outside of the bone marrow, often in the peripheral nervous system. These tumours can be benign or malignant and may involve various structures such as nerves, meninges, or soft tissues.

**Why the Correct Answer is Right**
Extramedullary tumours can originate from various tissues, including nerve sheaths (schwannomas), meninges (meningiomas), or peripheral nerves (neurofibromas). The clinical presentation and management of these tumours depend on their location, histological type, and grade. For example, schwannomas are typically benign and can be managed with surgical resection, while meningiomas may require a combination of surgery and radiation therapy.

**Why Each Wrong Option is Incorrect**
**Option A:** Extramedullary tumours always present with systemic symptoms such as weight loss and fatigue. (Incorrect because many extramedullary tumours are localized and may not present with systemic symptoms initially.)
**Option B:** Extramedullary tumours are exclusively benign and do not metastasize. (Incorrect because while many extramedullary tumours are benign, some can be malignant and metastasize, such as peripheral nerve sheath tumours.)
**Option C:** Extramedullary tumours always require chemotherapy as part of their management. (Incorrect because the treatment of extramedullary tumours depends on their histological type, grade, and location, and may not always involve chemotherapy.)

**Clinical Pearl / High-Yield Fact**
Extramedullary tumours can be classified based on their location, such as intracranial, spinal, or peripheral nerve tumours. A thorough understanding of the clinical presentation, imaging characteristics, and management options for each type of tumour is essential for accurate diagnosis and treatment.

**Correct Answer:** D. Extramedullary tumours always require chemotherapy as part of their management.