Thyroid cancer is usually asymptomatic in early stages and often discovered incidentally. As the tumor enlarges or invades adjacent structures, the following may develop:

1. Painless neck lump
   Most common first sign—unilateral, firm, poorly mobile on swallowing, slowly but steadily enlarging .
2. Hoarseness
   Persistent and unrelenting hoarseness due to recurrent laryngeal nerve invasion and vocal-cord palsy .
3. Dysphagia
   Compression or invasion of the oesophageal entrance causes globus sensation and progressive difficulty swallowing solids .
4. Dyspnoea
   Tracheal compression or intraluminal growth produces inspiratory stridor and orthopnoea that worsen when lying flat .
5. Cervical lymph-node swelling
   Firm, matted nodes in the lateral neck often indicate regional metastasis .
6. Throat or referred ear pain
   Late-stage perineural invasion leads to persistent sore throat or ipsilateral otalgia .
7. Less common features
   Medullary carcinoma may secrete bioactive substances causing diarrhoea and flushing; anaplastic cancer presents with rapidly enlarging mass and severe airway compromise .

Any neck lump that is hard, progressively enlarging and fixed, or symptoms of hoarseness or dysphagia lasting >2 weeks, warrants urgent ultrasound and fine-needle aspiration.