Differentials

Common

Colloid nodule

History

no specific history unless the nodule is large and causes mass effect; may have incidental radiologically-detected mass

Exam

may have palpable mass

1st investigation
  • thyroid-stimulating hormone (TSH):

    normal

  • ultrasound:

    complex appearance with both cystic and solid features; internal echo reflectors with 'ring-down' or 'comet tail' artifact

Other investigations
  • fine needle aspiration:

    predominance of abundant, thick colloid material with cracking or bubble pattern and benign-appearing follicular epithelial cells in honeycomb arrangement

Thyroid adenoma or hyperplastic nodule, single (solid or complex)

History

more common among patients with a history of high-dose ionising radiation exposure to the head and neck; however, most nodules do not present with historical findings suggesting their presence unless they cause obstructive symptoms due to large size; may have incidental radiologically-detected mass

Exam

may have palpable mass

1st investigation
  • thyroid-stimulating hormone (TSH):

    normal

  • ultrasound:

    solid homogeneous nodules with a hypoechoic vascular halo; complex nodules have both solid and cystic components

Other investigations
  • fine needle aspiration (FNA):

    abundant follicular cells in clusters forming microfollicles, and small monolayered sheets; individual cells show scanty, ill-defined cytoplasm and oval nuclei with regular nuclear contours and inconspicuous or prominent nucleoli; ultrasound is useful to guide FNA of complex nodules; fluid may be blood-tinged

Non-toxic multinodular goitre

History

no specific history that is suggestive unless the nodules are large and cause mass effect

Exam

thyroid nodules may or may not be palpable

1st investigation
  • thyroid-stimulating hormone (TSH):

    normal

Other investigations
  • ultrasound:

    multiple nodules, which may be solid or cystic depending on aetiology

Differentiated thyroid cancer (papillary, follicular)

History

frequently asymptomatic, presence of a thyroid nodule, dysphonia, prior head and neck irradiation, family history of first-degree relative with history of differentiated thyroid carcinoma; female sex, mean age of diagnosis 45 years (papillary); mean age of diagnosis 50 years (follicular)

Exam

physical characteristics of a thyroid nodule are poor predictors of malignancy; however, the following characteristics portend a higher risk of malignancy: nodules >4 cm in size, firmness on palpation, fixation of the nodule to adjacent tissues, cervical lymphadenopathy, and vocal cord paralysis

1st investigation
  • thyroid-stimulating hormone (TSH):

    usually normal

    More
  • ultrasound:

    presence of a solid component, microcalcifications, irregular margins, taller than wide shape, hypoechoic sonographic appearance

Other investigations
  • fine needle aspiration:

    enlarged, oval, and irregular nucleus; eccentric and often multiple micronucleoli; fine, pale chromatin, longitudinal intranuclear grooves, and intranuclear pseudo-inclusions (papillary); although both benign and malignant follicular lesions appear similar, increased atypia is often suggestive of follicular cancer, which often requires histology for definitive diagnosis

Uncommon

Toxic adenoma, single

History

clinically, these patients often present with thyrotoxicosis; patients tend to be younger (<40 to 50 years)

Exam

toxic adenomas may or may not be palpable; patient should be evaluated for signs of hyperthyroidism, which include tachycardia, arrhythmias, muscle wasting, tremor, brisk reflexes, and friable hair

1st investigation
  • thyroid-stimulating hormone (TSH):

    low

    More
Other investigations
  • free T4, free T3:

    high normal to above normal

  • radioactive iodine uptake scan:

    focal uptake in the hyperfunctioning nodule and diminished uptake in the remainder of the gland

Toxic multinodular goitre

History

thyroid gland enlargement and symptoms of hyperthyroidism such as irritability, increased perspiration, heat intolerance, palpitations, tremors, anxiety, insomnia, fine brittle hair, frequent bowel movements, and weight loss; patients usually >40 to 50 years

Exam

thyroid nodules may or may not be palpable; other non-specific signs of hyperthyroidism include tachycardia, arrhythmias, muscle wasting, tremor, brisk reflexes, and friable hair

1st investigation
  • thyroid-stimulating hormone:

    low

Other investigations
  • free T4 and free T3:

    high

  • radioactive iodine uptake scan:

    focal uptake in multiple hyperfunctioning nodules and diminished uptake in the remainder of the gland

Medullary thyroid cancer

History

family history of medullary thyroid cancer, multiple endocrine neoplasia syndromes 2A and 2B

Exam

physical characteristics of a thyroid nodule are poor predictors of malignancy; however, the following characteristics portend a higher risk of malignancy: nodules >4 cm in size, firmness on palpation, fixation of the nodule to adjacent tissues, cervical lymphadenopathy, and vocal cord paralysis

1st investigation
  • thyroid-stimulating hormone (TSH):

    usually normal

    More
  • ultrasound:

    solid hypoechoic nodule with echogenic foci in 80% to 90% of tumours due to amyloid deposition and associated calcification

Other investigations
  • fine needle aspiration (FNA):

    cellular aspirate consisting of round-to-oval cells arranged mainly as single cells or loosely cohesive groups; nuclear chromatin is similar to that seen in neuroendocrine tumours - salt and pepper type with inconspicuous nucleoli; some tumour cells can assume a 'spindle shape'; immunostains positive for calcitonin; FNA needle wash or cell block made during FNA can be tested for calcitonin, which may establish the diagnosis

  • calcitonin:

    high

    More

Anaplastic thyroid cancer

History

rapidly enlarging, painful neck mass; dysphagia, dysphonia, stridor

Exam

irregular fixed thyroid mass invading into surrounding tissue, fixed vocal cords, neck lymphadenopathy

1st investigation
  • thyroid-stimulating hormone (TSH):

    usually normal

    More
  • ultrasound:

    hypoechoic tumour with ill-defined margins diffusely involving the entire lobe or gland; usually has multiple areas of necrosis and nodal and distant metastases are often noted

Other investigations
  • fine needle aspiration:

    extreme cellular pleomorphism, numerous mitoses

  • ¹⁸FDG PET/CT:

    uptake of radioactive marker by tumour. MORE: Preferred test to determine extent of disease, which is key to management decisions. Dedicated body CT or MRI scan may be used if not PET is not available.

Lymphoma

History

rapidly enlarging, painless neck mass; compressive symptoms, history of chronic lymphocytic thyroiditis

Exam

painless neck mass that is fixed to surrounding tissues; unilateral or bilateral neck lymph node enlargement is present in about 50% of patients; should be differentiated from anaplastic carcinoma​

1st investigation
  • thyroid-stimulating hormone (TSH):

    usually normal

    More
  • ultrasound:

    diffuse involvement may result in heterogeneous echo pattern or simple enlargement of the gland with normal echo pattern; usually has associated round, hypoechoic, reticulated lymphomatous nodes in the neck; background of previous Hashimoto's thyroiditis in the form of echogenic fibrous strands within the thyroid gland is often seen

Other investigations
  • fine needle aspiration:

    abundant lymphocytes, which may be difficult to distinguish from chronic thyroiditis; immunohistochemical studies are helpful in identification of lymphoid proliferation and usually show B-cell markers

Simple epithelial-lined thyroid cyst

History

no specific history unless the nodule is large and causes mass effect

Exam

may have palpable mass

1st investigation
  • thyroid-stimulating hormone (TSH):

    normal

  • ultrasound:

    fluid with lack of internal echoes

Other investigations
  • fine needle aspiration:

    generally not required; when done, presence of fluid that may be clear, colourless

Thyroglossal duct cyst

History

painless neck mass (intermittent enlargement possible), dysphagia (rare and can occur with or without tongue base involvement), usually painless but rarely may become infected and cause fever and pain

Exam

thyroglossal duct cyst moves on protrusion of tongue as well as with swallowing; this may help to differentiate it from thyroid nodules, which do not move with protrusion of the tongue

1st investigation
  • thyroid-stimulating hormone (TSH):

    normal

  • ultrasound:

    well-circumscribed, anechoic midline mass above the level of the thyroid

Other investigations

    Acute suppurative thyroiditis

    History

    thyroid pain, fever, dysphagia

    Exam

    overlying erythema, asymmetrical tender goitre, neck lymphadenopathy

    1st investigation
    • FBC:

      increased WBC count

    • thyroid-stimulating hormone (TSH):

      usually normal

    Other investigations
    • ultrasound:

      fluid collection

    Subacute granulomatous thyroiditis

    History

    occurs predominantly in women, peak incidence is between 30 and 50 years of age, painful and enlarged thyroid, fever, symptoms of upper respiratory tract infection

    Exam

    thyroid palpation usually reveals exquisite thyroid tenderness

    1st investigation
    • thyroid-stimulating hormone (TSH; may also include free T4/T3):

      variable, depending on phase

      More
    Other investigations

      Chronic lymphocytic (Hashimoto's) thyroiditis

      History

      often results in hypothyroidism with rare, transient bouts of hyperthyroidism

      Exam

      painless, irregular, firm goitre of variable size on palpation

      1st investigation
      • thyroid-stimulating hormone (TSH):

        high/normal

      Other investigations
      • thyroid hormones:

        low/normal

      • anti-thyroid peroxidase antibodies:

        high titres

      • ultrasound:

        heterogeneous and hypoechoic thyroid parenchyma that may be hypervascular; prolonged course can lead to formation of pseudonodules

      Painless lymphocytic thyroiditis

      History

      generally painless, may present with small goitre, usually among females, may be symptoms of hyperthyroidism such as palpitations, heat intolerance, and weight loss in initial phase, and a presentation consistent with hypothyroidism in the later phase

      Exam

      half of the patients may have painless goitre

      1st investigation
      • thyroid-stimulating hormone (TSH):

        variable, depending on phase

        More
      Other investigations
      • anti-thyroid peroxidase antibodies:

        often present

      • radioactive iodine uptake scan:

        decreased uptake

      Graves' disease

      History

      bulging of eyes, neck mass, and symptoms of hyperthyroidism such as irritability, increased perspiration, heat intolerance, palpitations, tremors, anxiety, insomnia, fine brittle hair, frequent bowel movements, and weight loss

      Exam

      diffuse thyroid enlargement, exophthalmos with lid retraction, pretibial myxoedema; other non-specific signs of hyperthyroidism include tachycardia, arrhythmias, muscle wasting, tremor, brisk reflexes, and friable hair

      1st investigation
      • thyroid-stimulating hormone (TSH):

        low

      Other investigations
      • free T4 and free T3:

        high

      • radioactive iodine uptake scan:

        diffusely elevated uptake throughout the thyroid gland

      • thyrotropin-receptor antibodies (TRAb):

        usually positive

        More

      Enlarged parathyroid gland(s): benign

      History

      no specific neck-related symptoms; however, hypercalcaemia may cause nausea, abdominal pain, constipation, fatigue, and altered mental status

      Exam

      rarely has palpable neck mass, manifestations of hypercalcaemia if present include proximal muscle weakness, hyperreflexia, lethargy, and stupor

      1st investigation
      • serum calcium level:

        normal/high

      • thyroid-stimulating hormone (TSH):

        normal

      Other investigations
      • parathyroid hormone:

        normal/high

      • 25-hydroxy vitamin D:

        low/normal

      • ultrasound:

        oblong or teardrop shape, characteristic location close to posterior-inferior border of thyroid, homogeneous and hypoechoic appearance and feeding artery derived from inferior thyroidal artery or an arc of perfusion in colour Doppler ultrasonography

      Parathyroid carcinoma

      History

      hoarseness; hypercalcaemia may cause nausea, abdominal pain, constipation, fatigue, and altered mental status

      Exam

      a palpable neck mass is present in 70% of cases, which is not a common finding in benign hyperparathyroidism;​ manifestations of hypercalcaemia if present include proximal muscle weakness, hyperreflexia, lethargy, and stupor

      1st investigation
      • serum calcium level:

        elevated

      • thyroid-stimulating hormone (TSH):

        normal

      Other investigations
      • parathyroid hormone:

        elevated (6-10 times upper limit of normal)

      • ultrasound:

        characteristic location close to posterior-inferior border of thyroid; hypoechoic soft tissue mass with irregular, poorly defined borders and sign of invasion of adjacent structures

      • 99mTc-methoxyisobutyl isonitrile scintigraphy:

        increased focal uptake in nodule (91% sensitivity)

        More

      Metastasis to the thyroid of non-thyroidal malignancies

      History

      malignancy in another organ; may have neck mass detected radiologically

      Exam

      may have palpable neck mass

      1st investigation
      • thyroid-stimulating hormone (TSH):

        usually normal

      • ultrasound:

        nodules have well-defined margins, tend to occur predominantly in the lower pole; metastases may have a heterogeneous echo pattern when the gland is diffusely involved

      Other investigations
      • fine needle aspiration:

        variable cytological characteristics based on the primary malignancy

        More

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