CALCA and medullary thyroid gland carcinoma: The disease manifests either as differentiated thyroid cancer (DTC), poorly differentiated thyroid cancer (PDTC), or undifferentiated or anaplastic thyroid cancer (ATC)—all of which are derived from thyroid follicular cells—or medullary thyroid cancer (MTC), which is derived from non-follicular calcitonin + cells [9].