Commonest posterior mediastinal tumour is –
**Core Concept**
Neuroblastoma is a type of cancer that originates from the neural crest cells of the sympathetic nervous system. It is the most common extracranial solid tumor in children and is frequently found in the posterior mediastinum.
**Why the Correct Answer is Right**
Neuroblastoma arises from the neural crest cells that migrate to the posterior mediastinum during embryonic development. It is thought to arise from the sympathetic nervous system, specifically from the adrenal glands or the paraspinal regions. The tumor cells in neuroblastoma are characterized by their ability to differentiate into various cell types, including neuroblasts, ganglion cells, and Schwann cells. The posterior mediastinum is a common location for neuroblastoma due to the presence of sympathetic nervous tissue.
**Why Each Wrong Option is Incorrect**
**Option A:** **Lymphoma** - While lymphoma can occur in the mediastinum, it is not the most common posterior mediastinal tumor. Lymphoma typically arises from the lymphoid tissues in the mediastinum, such as the thymus or lymph nodes.
**Option B:** **Thymoma** - Thymoma is a type of tumor that arises from the epithelial cells of the thymus. While it can occur in the anterior mediastinum, it is not the most common posterior mediastinal tumor.
**Option C:** **Teratoma** - Teratoma is a type of germ cell tumor that can occur in the mediastinum. However, it is not the most common posterior mediastinal tumor and is typically found in the anterior mediastinum.
**Clinical Pearl / High-Yield Fact**
Neuroblastoma is often associated with paraneoplastic syndromes, such as hypertension, diarrhea, and flushing, due to the release of catecholamines by the tumor cells.
**Correct Answer: C. Neuroblastoma**