Variants of Papillary Thyroid Cancer (PTC)

  • Other variants of PTC:
    • Several variant subtypes of papillary thyroid cancer have been described:
      • Based upon histologic differences from classical papillary thyroid cancers:
        • But considered to be papillary cancers because of the characteristics of the tumor cell nuclei
  • The insular variant of papillary thyroid cancer:
    • Histologically it is characterized by high cellularity with scant colloid and by well-defined solid nests of tumor (insulae) of monotonous round cells:
      • Often separated by fibrous bands:
        • But the tumor cell nuclei have the same characteristics as do the nuclei of classical papillary thyroid cancers
    • Some tumors have papillary differentiation:
      • Whereas others are categorized as a variant of FTC
    • The mean tumor diameter at presentation is greater than 5 cm
    • Cervical nodal metastases:
      • Are seen in more than half of patients
    • Up to 70% have distant metastases
    • Viewed as an intermediate tumor between that of classic PTC and anaplastic thyroid carcinoma:
      • It is associated with 30-year cancer-specific mortality rate of 25% (versus 8% for classic PTC)
  • The columnar variant, which consists of elongated cells with palisading nuclei:
    • This very rare subtype accounts for only 0.15% to 0.2% of all PTCs
    • It may be confused with TCV as its cells have a height twice the width:
      • But the elongated nuclei and prominent nuclear stratification distinguish it from other histologic variants
    • The encapsulated version of this tumor has a very good prognosis:
      • However, the diffusely invasive form is very aggressive
    • Unencapsulated tumors are:
      • Larger at presentation
      • Have a high rate of extracapsular spread
      • Have distant metastases:
        • In up to 87%
      • Mortality is significantly higher than it is for classic PTC
  • The Hürthle or oxyphilic variant:
    • Which has cellular features of Hürthle cell carcinomas but cells that are arranged in papillary formations
  • The solid or trabecular variant:
    • This tumor may be seen in adults:
      • But is more commonly associated with children after radiation exposure, particularly after the Chernobyl accident
    • Nuclear features:
      • Are similar to classic PTC
    • The architectural pattern:
      • Is predominantly or exclusively solid
    • The majority of tumors present with:
      • Extrathyroidal invasion
    • Cervical node metastases are common
    • In children, this tumor has a:
      • Similar survival rate as that of classic PTC
    • The prognosis is less clear for adults:
      • As conflicting mortality rates with this tumor have been described
  • The clear cell variant:
    • Which must be distinguished from clear cell carcinomas of other organs such as:
      • The kidney or colon that have metastasized to the thyroid
  • The diffuse sclerosing variant:
    • Characterized by:
      • Diffuse involvement of the thyroid
      • Stromal fibrosis
      • Prominent lymphocytic infiltration
    • This variant represents approximately:
      • 5% of all PTCs
    • Is seen more frequently in children:
      • Exposed to radiation at Chernobyl
    • diffusely infiltrative tumor:
      • It is typically bilateral
      • With a high rate of lymph node metastases:
        • Approaching 70%
    • The histologic appearance of the tumor:
      • May be confused with chronic thyroiditis
    • It is characterized by:
      • Squamous metaplasia
      • Sclerosis
      • Psammoma bodies
      • Abundant lymphatic invasion
    • Rates of distant metastases are variably reported:
      • But appear to be higher than that of classic PTC
    • In spite of this seemingly aggressive behavior, there is debate about whether long-term prognosis is worse than for classic PTC
  • The cribriform morular variant:
    • Which has a prominent cribriform pattern with solid and spindle cell areas as well as squamous morules
    • This variant is often associated with familial adenomatous polyposis
  • The hobnail variant:
    • Harbors BRAF V600E mutations
    • Appears to be associated with a:
      • High risk of distant metastases and an increased disease-specific mortality
  • These variants are all rare, and therefore, little information about their characteristics is available:
    • In general, however, they are thought to be more aggressive than classical papillary cancers
    • As a result, patients with these tumors are usually managed more aggressively than are those with classical papillary cancer of the same stage

#Arrangoiz #ThyroidSurgeon #CancerSurgeon #SurgicalOncologist #HeadandNeckSurgeon #EndocrineSurgery #ThyroidCancer #InsularVariant #ColumnarVariant #DiffuseSclerosingVariant #ClearCellVariant #OtherVariantsofPapillaryThyroidCancer #Miami #Mexico #MountSinaiMedicalCenter

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