Thyroid gland
Benign neoplasms
Solitary thyroid nodule

Author: Sheren Younes, M.D. (see Authors page)

Revised: 27 January 2017, last major update July 2014

Copyright: (c) 2014-2017, PathologyOutlines.com, Inc.

PubMed Search: solitary thyroid nodule
Cite this page: Solitary thyroid nodule. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/thyroidsolitary.html. Accessed October 20th, 2017.
Definition / general
  • A discrete lesion within the thyroid gland that is palpably or ultrasonographically distinct from surrounding thyroid parenchyma
  • Up to 5% are malignant (Oncologist 2008;13:105)
  • Single and cold (on nuclear scan) nodules are higher risk for malignancy, but 80 - 90% are benign; other risk factors are radiation to head and neck, rapidly enlarging nodule, ipsilateral adenopathy, male patient, age < 20 years or > 70 years
  • Cysts may represent cystic degeneration of follicular adenoma or portions of multinodular goiters
Epidemiology
  • Usually > 1 cm
  • Variable prevalence worldwide, depending on iodine deficiency
Etiology
  • Colloid nodule (hyperplastic nodule)
  • Thyroid cysts
  • Focal / asymmetrical thyroiditis, acute suppurative, granulomatous or Hashimoto's thyroiditis
  • Thyroid adenoma, ectopic thymic tissue, other benign tumors
  • Primary thyroid malignancies and metastasis:
    • Papillary carcinoma
    • Follicular carcinoma
    • Medullary carcinoma
    • Anaplastic carcinoma
    • Primary lymphoma of thyroid
    • Metastatic carcinoma (especially breast and renal cell carcinoma)
Diagnosis
  • Use these factors:
    • Asymptomatic
    • Pain and rapid enlargement
    • Age and sex of patient
    • History of prior radiation exposure
    • Compression symptoms on surrounding structures
    • Lymph node involvement or metastasis
    • Hypo-, eu-, or hyperthyroidism
    • Thyroid function tests
    • Ultrasound, radiologic investigations
  • Biopsy
  • Evaluate with ultrasound guided fine needle aspiration (see Cytology: FNA) to rule out malignancy
  • Nonpalpable nodules greater than 1.0 to 1.5 cm represent an absolute indication to perform an ultrasound guided fine needle biopsy (ANZ J Surg 2006;76:381, Hormones (Athens) 2007;6:101)
Radiology description
  • Thyroid ultrasound
    • Most effective
    • Determine size and shape of nodule, presence of associated nodules or lesions
    • Determine if cystic or solid
      • Benign lesions are pure cystic, spongiform or septate, multiple
      • Suspicious features are solid, calcification, hypoechoic lesion and increased vascularity
    • Radionucleotide scanning
      • Hot, cold and warm nodules
    • CT and MRI help evaluate extent of lesion if malignant
Case reports
Clinical images

Images hosted on other servers:

Multiple hypoechoic lesions

Thyroid ultrasound, left thyroid lesion

Microscopic (histologic) description
  • Description of histology for primary lesion:
    • Hashimoto's thyroiditis: small follicles with Hürthle cell change and marked lymphoplasmacytic infiltrate
    • Follicular adenoma / carcinoma: follicular proliferation, variable colloid component, trabecular, solid, micro and macrofollicular architecture; vascular and capsular invasion are diagnostic of malignancy
    • Papillary carcinoma: true papillae, cells have characteristic nuclear features, psammoma bodies
Microscopic (histologic) images

Images hosted on other servers:

Hemangioma

Metastatic squamous cell carcinoma

Irregular nodules (ectopic thymus)

Cytology description
Positive stains