Thyroid nodule differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]

Overview

Neck masses can be mistaken with thyroid nodules. The most important neck masses that can be mistaken with thyroid nodules include: Thyroglossal duct cyst, parathyroid cancer, parathyroid cyst, and branchial cleft cyst. While the diagnosis of a thyroid nodule is established, thyroid nodule should be differentiated based on benign or malignant features and the type of nodule.

Thyroid Nodule Differential Diagnosis

Neck masses can be mistaken with thyroid nodules. While the diagnosis of a thyroid nodule is established, thyroid nodule should be differentiated based on benign or malignant features and the type of nodule:

Disease	Manifestation	Spread	Nodular growth	Laboratory		Imaging	Pathology	Associated findings
				TSH	FT4/T3
Colloid adenoma	Benign Noncancerous enlargement of thyroid tissue May be painful	−	Intermediate Slow	NL	NL	Iso- to hypoechoic May have internal cystic or heterogeneous change May have calcification Multiple echogenic foci (of inspissated colloid) with comet tail artifact	Hyperplasia of colloid parenchyma of thyroid gland	May progress to carcinoma
Hashimoto's thyroiditis	Benign Rarely painful May be accompanied with fever	−	Rapid Intermediate	↓↓	↓	Hypoechoic micronodules (1-6 mm) with surrounding echogenic septations	Massive infiltration of the thyroid gland by lymphocytes and plasma cells Germinal centers Thyroid follicles are usually absent and the few remaining follicles are devoid of colloid Hurthle cells	HLA-A HLA-B Autoimmune disease of thyroid gland
Cysts nodule	Benign Most common cause of painful neck lesion	−	Rapid Intermediate	NL	NL	Cystic non-calcified nodules	Follicular cells Macrophages RBC Colloid	Mostly due to degenerating thyroid adenomas
Disease	Manifestation	Spread	Nodular growth	TSH	FT4/T3	Imaging	Pathology	Associated findings
Follicular adenoma	Benign Rarely painful	−	Intermediate Slow	↓↓	↑	Thin peripheral halo Predominantly cystic or mixed cystic and solid lesions Isoechoic or predominantly anechoic	Depends on type	PAX8-PPAR gamma 1
Hyperplastic nodule	Benign Rarely painful	−	Rapid Intermediate	↓↓	↑
Macrofollicular adenoma	Benign Rarely painful	−	Intermediate Slow	↓↓	↑
Microfollicular or cellular adenoma	Benign Rarely painful	−	Intermediate Slow	↓↓	↑
Hürthle cell adenoma	Benign Rarely painful	−	Intermediate Slow	↑↓	↑↓
Disease	Manifestation	Spread	Nodular growth	TSH	FT4/T3	Imaging	Pathology	Associated findings
Papillary carcinoma	Malignant Fixed Painless	Spread to lymph nodes and vessels Metastases to: Lung Skeleton	Intermediate Slow	NL	NL	Solitary mass usually with an irregular outline, located in the subcapsular region Small punctate regions of echogenicity representing microcalcifications (psammoma bodies)	Unencapsulated and may be partially cystic Papillae consisting of one or two layers of tumor cells surrounding a well-defined fibrovascular core Large, oval, and appear crowded and overlapping nuclei May contain hypodense powdery chromatin, cytoplasmic pseudoinclusions due to a redundant nuclear membrane, or nuclear grooves	RET/PTC NTRK1 RAS BRAF
Follicular carcinoma	Malignant Fixed Painless Most common thyroid cancer in iodine deficient areas	Spread to lymph nodes and vessels Metastases to: Bone Lung	Intermediate Slow	↑↓	↑↓	Lesions are typically hypoechoic Usually lacks cystic change	FLUS Tumor capsule Vascular invasion	RAS mutations PAX8-PPAR gamma 1
Medullary carcinoma	Malignant Mainly manifest paraneoplastic symptoms: Diarrhea Itching Flushing	Spread to lymph nodes May spread to vessels Metastasis locally to neck Can metastasize to all body organ systems	Intermediate Slow	NL	NL	Unifocal May present as multifocal	Hypoechoic Microcalcifications	May be associated with other co-existing diseases Associated with high levels of calcitonin
Disease	Manifestation	Spread	Nodular growth	TSH	FT4/T3	Imaging	Pathology	Associated findings
Anaplastic carcinoma	Very malignant, always considered as stage IV Dyspnea Dysphagia Vocal cord paralysis Hoarseness of voice	Spread to lymph nodes and vessels Very aggressive Invade directly into adjacent organs, such as the trachea, larynx, esophagus, blood vessel and muscle	Slow	↓	↑	Microcalcifications Infiltrative lesion	Cytologically malignant: Huge nuclear-cytoplasmic ratio Mitosis Presence or absence of necrosis	P53 BRAF
Primary thyroid lymphoma	Malignant Vocal cord paralysis Dyspnea Dysphagia	Spread to lymph nodes MALT lymphoma less aggressive Diffuse large cell lymphomas more aggressive	Intermediate Slow	NL	NL	Nodular (hypoechoic mass), diffuse (mixed echotexture) or mixed Calcifications uncommon	Lymphoepithelial lesion Plasma cells Thyroid parenchyma displaced by lymphocytes	BRAF NRAS MAPK Hashimoto's thyroiditis
Metastatic carcinoma	Malignant Thyroid and extra thyroid manifestations	Spread to lymph nodes and vessels Metastases	Intermediate Slow	↑↓	↑↓	−	−	Malignant melanoma Lung cancer breast cancer Renal cancer Gastrointestinal cancer
Thyroglossal duct cyst	Mostly midline Can be painful if get infected	−	−	NL	NL	Cyst in subhyoid portion or lateral tip of the hyoid bone	−	NA
Disease	Manifestation	Spread	Nodular growth	TSH	FT4/T3	Imaging	Pathology	Associated findings
Branchial cleft cyst	Cystic mass that develops under the skin in the neck between the sternocleidomastoid muscle and the pharynx	May adhere to great vessels at the mandibular angle	−	NL	NL	Cyst between sternocleidomastoid and pharynx	−	NA
Neck abscess	Painful mass in the neck, may be accompanied with erythema	Spread to lymph nodes	Rapid	NL	NL	Cyst with hyperechoic debris containing pus	−	NA
Parathyroid cyst	Painless mass	−	Rapid Intermediate	NL	NL	Cystic lesion that is uniformly anechoic	−	NA
Parathyroid cancer	Lymphadenopathy Palpable lump in the neck	Spread to lymph nodes and vessels Rarely distant metastases, mainly thyroid gland, overlying strap muscles, recurrent laryngeal nerve, trachea, or esophagus	Slow Intermediate	NL	NL	Normal thyroid size with a complex echogenic structure May contain hyperechoic solid part and several centrally located anechoic cavities	Tumor cells form branching cord surrounded by fat cells with areas of fibrosis and chronic inflammatory cells or abundant granular eosinophilic cytoplasm	FIHP MEN1
Disease	Manifestation	Spread	Nodular growth	TSH	FT4/T3	Imaging	Pathology	Associated findings