Malignant thyroid adenoma refers to thyroid cancer, of which undifferentiated carcinoma is the most malignant and has a high mortality rate. It can be asymptomatic in the early stages and progresses rapidly once detected, with symptoms such as hoarseness and dyspnea appearing soon after, and most die within 1 year.
There are four common pathological classifications of thyroid cancer: (1) papillary adenocarcinoma, which accounts for 60% to 80%; and (2) follicular adenocarcinoma, which accounts for 10% to 28%. It originates from the follicular epithelium of the thyroid gland and has a good prognosis after treatment, which is called differentiated thyroid cancer; (3) medullary carcinoma, which originates from the parafollicular cells or c cells of the thyroid gland, accounting for 3% to 10%; (4) undifferentiated carcinoma, accounting for 3% to 8%. Among thyroid cancers, more than 90% are differentiated thyroid cancers. Either type of thyroid cancer has no obvious symptoms in the early stage and is mostly detected by clinical examination. In advanced stages, symptoms such as lymph nodes and thyroid enlargement may appear. The prognosis for differentiated thyroid cancer is better.
Undifferentiated carcinoma progresses rapidly, with rapid onset of clinical symptoms such as hoarseness, dysphagia, and dyspnea. The prognosis is poor, most die within 1 year, and the 5-year survival rate is only 5%-15%.