PopAds.net - The Best Popunder Adnetwork

Neoplastic lesions of thyroid

 

There are some clinical criterias that provide clues to nature of a thyroid nodule.

    • Solitary nodules: They are more likely to be neoplastic than the multiple nodules
    • Nodules in young patients tend to be neoplastic as compared to the elderly patients
    • Nodules in males are more likely to be neoplastic
    • Hot nodules have more chances of being benign
    • Chances of thyroid malignancy are more if there is previous history of radiation therapy

Major portion of neoplastic thyroid lesions are carcinomas. The major subtypes of carcinomas are,

    • Papillary carcinoma: more than 85% of cases
    • Follicular carcinoma: second common one
    • Medullary carcinoma
    • Poorly differentiated carcinoma
    • Anaplastic thyroid carcinoma

Pathogenesis of carcinomas:

    • Genetic factors:
      1. Papillary carcinoma:
        1. RET/PTC rearrangements (translocation or inversion)
        2. BRAF point mutations
      2. Follicular carcinoma:
        1. RAS point mutations
        2. PIK3CA gain of function mutations or amplifications
    • PAx8-PPARG translocation
    1. PTEN loss of function mutations
    1. Anaplastic carcinoma:
      1. PI3K mutations
      2. RAS mutations
    • PTEN mutations
    1. Inactivation of TP53
    2. Activating mutations of beta catenin
    1. Medullary carcinoma:
      1. RET mutations
    • Environmental factors:
      1. Papillary carcinoma: ionizing radiation and iodine excess diets
      2. Follicular carcinoma: deficiency of dietary iodine.

 

Papillary carcinoma

It is the most common primary neoplastic lesion of thyroid.

Clinical presentation: can be any of the following,

    • May be asymptomatic.
    • Single nodule that moves with swallowing.
    • Mass in cervical lymph node
    • Hoarseness and dysphagia

     Etiology:

    • Excessive iodine
    • External radiation
    • Autoimmune diseases: Graves disease patients have increased incidence
    • Hormonal factors: increased parity, oral contraceptives, fertility problems and increased age at first pregnancy
    • Genetic syndromes: increased risk of papillaey carcinoma in patients with Familial adenomatous polyposis, Peutz-Jeghers syndrome, ataxia-telengiectasia and HNPCC.

    Gross appearance:

    • Solitary or multifocal
    • Well-circumscribed or even encapsulated
    • Average 2-3 cm in size
    • White in colour
    • Firm in consistency
    • Calcification can be present

   Microscopic features:

    • Papillary arrangement
    • Papillae contain a fibrovascular core lined by single or multiple layers of cuboidal epithelial cells
    • Psammoma bodies representing ghost papillae are usually present in cores or stroma but not within neoplastic follicles.
    • Nuclei are optically clear or empty appearing, usually called orphan-annie eye nuclei. Nuclei are larger, oval and overlapping.
    • Intranuclear groves
    • Intranuclear inclusions
    • Mitosis are exceptional
    • Finding a psammoma body in cervical lymph node is a strong evidence of a papillary cancer in thyroid.
    • Lymphatic invasion can be seen
    • Scattered lymphocytes at the egdes of the tumor are seen commonly.
    • Grading is not done as usually they are grade 1 tumors

    Prognosis:

 It has an excellent prognosis. Even if multiple metastasis are present the survival is prolonged. Important prognostic factors are,

    • Age: good in children and adolescents
    • Sex: females have good prognosis
    • Size: inverse correlation
    • Extrathyroid extension: adverse effect on prognosis
    • Poorly differentiated, squamous or anaplastic foci have negative effects on prognosis
    • BRAF mutations: tumors with BRAF mutations behave aggressively
    • Microscopic variants

   Microscopic variants:

    • Common in females:
      • Hobnail variant: New entity. There are micropapillae lacking fibrovascular cores. Cells have eosinopilic cytoplasm and buldging of nuclei at tip of cell giving it hobnail appearance. BRAF mutations. Aggressive features like necrosis, mitosis and extrathyroid extension can be seen
      • Cribriform-morular variant: Exclusive in women. Multifocal tumors with cribriform or spindle cell growth pattern. The nuclei are optically clear by biotin. Beta cetenin staining is nuclear. APC germline mutations
    • Common in children:
      • Solid variant: solid growth is more than 50%. Mostly associated with history of radiation.RET/PTC gene rearrangements
      • Diffuse sclerosing variant: also effects young adults. Lymphocytic infiltrate are seen around tumor foci. Area of squamous metaplasia are also seen. Lesions recur. Aggressive biological features, distant and cervical lymph node metastasis is seen. RET/PTC rearrangements
    • Others:
      • Follicular variant : Almost total follicular pattern.clear nuclei, psammoma bodies and demoplastoc response at invasive areas. NRAS mutations.
      • Tall cell variant: cells 2-3 times taller than wider. At least 30% cells should fulfil the criteria. Less favourable prognosis than papillary carcinoma. BRAF and TERT mutations.
      • Columnar cell variant: extremely poor prognosis. Papillary arrangement. Tall columnar cells with hyoerchromatic nuclei and nuclear stratification. CDX2 is positive in 50% of cases. BRAF mutations
      • Warthin-like variant: Associated with chronic lymphocytic thyroiditis. Papillary architecture with brisk lymphoplasmacytic infiltrate. Cells have abundant eosinphilic cytoplasm. BRAF mutations
      • Papillary thyroid carcinoma with nodular fasciitis-like stroma: cords, tubules and papillary arrangement. Fasciitis-like stroma and nuclei with characteristic features of papillary carcinoma. Vimentin, desmin and smooth muscle actin are positive.
      • Encapsulated variant: 100% survival rate. Total encapsulation. Characteristic nuclear features and psammoma bodies.
      • Spindle cell type, clear cell type and oncocytic variant are rare variants

 

 

Dr Saadia Hafeez

Spread the love
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
PopAds.net - The Best Popunder Adnetwork