Neck lump, ultrasound and fine needle aspiration

Thyroid cancer is the classic warning about overdiagnosis from easy ultrasound.

Most thyroid nodules are benign and many small thyroid cancers grow slowly. The art is finding dangerous disease without chasing every tiny incidental nodule.

Educational, not personal medical advice. A growing neck lump, hoarseness, swallowing trouble, breathing symptoms, suspicious lymph node or history of radiation exposure needs assessment.
No

routine population ultrasound screening is recommended.

Ultrasound

risk-stratifies nodules and lymph nodes.

FNA

fine needle aspiration samples nodules that meet criteria.

Overdiagnosis

population ultrasound can make diagnoses soar without changing deaths.

Brief outline

Most thyroid cancers are papillary thyroid cancers.

Papillary and follicular thyroid cancers are differentiated cancers. Medullary thyroid cancer arises from C cells and can be hereditary. Anaplastic thyroid cancer is rare and aggressive.

Ultrasound image of papillary thyroid carcinoma.
Ultrasound features determine FNA need.

Detection frame

Detection begins with a palpable nodule, suspicious ultrasound, enlarged lymph node or high-risk history. It should not become ultrasound fishing in average-risk people.

Do not ignore

Most nodules are benign, but some signs matter.

Growing neck lumpA firm, enlarging or fixed thyroid nodule deserves ultrasound.
HoarsenessCan suggest recurrent laryngeal nerve involvement.
Swallowing or breathing difficultyCompression symptoms need prompt review.
Neck lymph nodesSuspicious cervical nodes can be the first sign.
Painful rapid growthCould be hemorrhage, thyroiditis, lymphoma or aggressive cancer.
Incidental noduleCommon on CT/MRI/ultrasound; management depends on size, age and suspicious features.

Risk and genetics

Radiation and inherited syndromes change risk.

Childhood radiationHead/neck/chest radiation increases risk.
Family historyFamilial non-medullary thyroid cancer is uncommon but relevant.
MEN2/RETMedullary thyroid cancer can be hereditary; RET testing changes family care.
PTEN/FAP/DICER1Selected syndromes can raise thyroid cancer risk.
Iodine and thyroid diseaseBackground thyroid disease can affect nodules but most nodules are benign.
Female sex and ageNodules and thyroid cancer are more common in women; aggressive biology can occur at any age.

Screening

Do not screen average-risk adults with ultrasound.

Routine thyroid ultrasound screening creates many diagnoses of tiny papillary cancers without clear mortality benefit. High-risk families and radiation-exposed patients are different.

First line

Neck ultrasound

Risk-stratifies nodules and cervical lymph nodes.

Blood test

TSH

Low TSH may lead to radionuclide scan for a hot nodule, which is rarely malignant.

Tissue

Fine needle aspiration

Samples nodules meeting size/risk criteria.

Cytology

Bethesda system

Classifies benign, suspicious, malignant and indeterminate results.

Selected

Calcitonin/RET

Important for suspected medullary thyroid cancer or MEN2 families.

Caution

Whole-body MRI

Often finds incidental thyroid nodules that then need ultrasound triage.

Images, labs and tissue

Ultrasound decides whether FNA is needed.

Ultrasound evaluates size, composition, echogenicity, margins, calcifications and lymph nodes. FNA cytology is reported using Bethesda categories; molecular tests help selected indeterminate nodules.

Ultrasound image of papillary thyroid carcinoma.
Ultrasound features determine FNA need.
Papillary thyroid carcinoma cytology.
FNA cytology guides surgery versus surveillance.
Gross thyroid cancer specimen.
Surgery and pathology define final staging.

Pros, cons and controversy

Thyroid ultrasound can be both helpful and harmful.

South Korea's thyroid ultrasound experience is often cited as a cautionary example of overdiagnosis: diagnoses rose dramatically, while mortality did not fall in the same way. Ultrasound is still the right test for a real nodule, suspicious lymph node or high-risk history; the problem is using it as broad average-risk population screening. The goal is to find clinically important cancer, not label every tiny papillary microcarcinoma.

Sources and trials

Good starting points.