Which of the following is true about medullary CA of thyroid –
**Core Concept**
Medullary carcinoma (CA) of the thyroid is a malignant tumor originating from the parafollicular cells (also known as C cells), which produce calcitonin. This cancer is characterized by its aggressive behavior and potential for metastasis.
**Why the Correct Answer is Right**
Medullary thyroid carcinoma (MTC) is associated with a genetic mutation in the RET proto-oncogene, leading to the activation of the tyrosine kinase receptor. This results in the uncontrolled proliferation of C cells, producing excessive calcitonin levels. The elevated calcitonin levels serve as a diagnostic marker for MTC. The tumor cells also produce other peptides, such as calcitonin gene-related peptide (CGRP), which contribute to the disease's pathophysiology.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might be a distractor related to the histological appearance of MTC, which is often characterized by spindle-shaped or plasmacytoid cells. However, this description does not accurately capture the specific genetic or molecular mechanisms underlying MTC.
**Option B:** This option might be a distractor related to the association of MTC with other thyroid conditions. While MTC can occur in association with other thyroid cancers, such as papillary thyroid carcinoma, this is not a defining characteristic of MTC.
**Option C:** This option might be a distractor related to the treatment of MTC. While surgical resection is a primary treatment for MTC, this option does not accurately capture the underlying pathophysiology of the disease.
**Clinical Pearl / High-Yield Fact**
MTC is often associated with a family history of the disease, and genetic testing for RET mutations can identify individuals at risk. Early detection and treatment are crucial for improving outcomes in patients with MTC.
**Correct Answer:** C.