**Question:** NOT True about Geomus tumour

A. Geomus tumours are common in children
B. Geomus tumours are benign tumours
C. Geomus tumours are caused by a genetic mutation
D. Geomus tumours are exclusively found in the brain

**Core Concept:** Geomus tumour is a type of tumour that refers to a group of tumours known as ganglioneuroblastomas, which primarily affect the sympathetic nervous system. These tumours are typically found in children under the age of three, specifically in the adrenal glands, mediastinum, and posterior abdominal wall.

**Why the Correct Answer is Right:** Geomus tumours are not common in children, as stated in option A. They are actually more prevalent in infants, particularly those under the age of three, as mentioned in option D.

**Why Each Wrong Option is Incorrect:**

Option B is incorrect because Geomus tumours are not exclusively benign (non-cancerous) tumours. They can be either benign (well-differentiated) or malignant (undifferentiated or poorly differentiated).

Option C is incorrect because the aetiology (cause) of Geomus tumours is not a specific genetic mutation. They result from the abnormal development and differentiation of neural crest cells, which are precursor cells to neurons and glial cells. The term "Geomus" is derived from the Greek words for "ganglion" (neural crest cell) and "muscle" (referring to the presence of muscle tissue in the tumour).

Option D is incorrect because Geomus tumours are not exclusively found in the brain. They can occur in other regions, such as the adrenal glands, mediastinum, and posterior abdominal wall, as mentioned in option C.

**Correct Answer:**

Geomus tumours are not exclusive to the brain, which is why option D is incorrect. The correct answer is:

**Correct Answer:** D. Geomus tumours are not found exclusively in the brain