Definition of Goiter

  • Both greatest diameter and goiter weight have been used to define thyroid enlargement:
    • In studies, methods for determining goiter size range from:
      • Physical examination measured in centimeters, to physical examination estimated in grams, to surgical specimen measured in centimeters or grams
      • Preoperative imaging diameters may also be used
  • The definition of goiter varies substantially among reports:
    • McHenry 80 g as the threshold value
    • Russell 100 g as the threshold value
    • Clark 200 g as the threshold value
  • Studies investigating radioiodine treatment for multinodular goiter:
    • Often define significant goiter as:
      • Greater than 100 g
  • Hegedus, Nygaard, and Hansen found that goiter surgical specimens:
    • Averaged:
      • 30 g for unilateral resection
      • 64 g for bilateral resection
  • Katlic, Grillo, and Wang reported that:
    • The average weight of substernal goiter was:
      • 104 g (range 25 to 357 g)
      • Greatest diameter averaging 9 cm (range 5 to 19 cm)
  • In a series of more than 200 cervical and substernal goiters treated at Massachusetts Eye and Ear Infirmary and Massachusetts General Hospital:
    • The mean weight was 143 g
    • The mean goiter size was 10.5 cm
  • The World Health Organization (WHO) 1960 grading system for clinical assessment of goiter defines:
    • Stage 0 as no enlargement
    • Stages 1 to 3 describe progressive goiter enlargement:
      • Stage 1A:
        • Includes patients with palpable abnormalities
      • Stage 1B:
        • Includes patients with palpable and visual abnormalities with the neck in extension
      • Stage 2:
        • Is defined as a goiter that is visible with the neck in neutral position
      • Stage 3:
        • As a goiter that is able to be visualized at a considerable distance
  • The WHO 1994 goiter classification system is more streamlined:
    • Grade 0:
      • Is defined as no palpable or visual abnormality
    • Grade 1:
      • Is defined as a palpable thyroid mass that is not visualized with the neck in neutral position
    • Grade 2:
      • As a visually apparent mass with the neck in neutral position
  • Substernal GoiterSynonyms:
    • Substernal goiter and its subtypes have been termed:
      • Retrosternal, subclavicular, intrathoracic, mediastinal, aberrant, wandering, and spring goiter, as well as goiter mobile and goiter plongeant
  • Numerous definitions and classification schemes have been proposed for substernal goiter:
    • Lahey and Swinton defined substernal goiter as:
      • A “gland in which the greatest diameter of the intrathoracic component by x-ray was well below the upper aperture of the thoracic inlet
    • Crile, in 1939, simply defined substernal goiter as:
      • A lesion extending to the aortic arch
    • Lindskog and Goldenberg in 1957 defined substernal goiter as:
      • A goiter whose lower border radiographically reaches the transverse process of the fourth thoracic vertebra or lower
    • Katlic, Grillo, and Wang described substernal goiter as:
      • When greater than 50% of the goiter is present substernally
    • Sanders et al. defined substernal goiter as:
      • That which requires mediastinal exploration and dissection for removal
  • Substernal classification schemes:
    • Higgins based his classification scheme on the percentage of goiter in the neck versus the percentage of goiter in the chest with:
      • Greater than 50% in the neck being described as:
        • Substernal
      • Greater than 50% in the chest as:
        • Partially intrathoracic
      • Greater than 80% in the chest as:
        • Completely intrathoracic
    • Cho, Cohen, and Som offered a grading system relating grade to percentage of goiter within the chest:
      • Grade I is defined as 0% to 25% of the goiter within the chest
      • Grade II as 26% to 50% of the goiter within the chest
      • Grade III as 51% to 75% of the goiter within the chest,
      • Grade IV as greater than 75% of the goiter within the chest
    • Shahian offered an interesting and detailed classification scheme:
      • Type I substernal goiter is associated with the anterior mediastinal extension:
        • Type IA involves “isolated” anterior mediastinal disease
        • Type IB involves “extensive” substernal involvement
      • Type II involves posterior mediastinal involvement:
        • Type IIA being isolated posterior mediastinal goiter
        • Type IIB posterior mediastinal goiter with ipsilateral extension relative to the thyroid lobe of origin
        • Type IIC contralateral extension relative to the thyroid lobe of origin:
          • C1 being retrotracheal
          • C2 being retroesophageal course
  • A classification system for substernal goiters is most useful when it takes into account the features of substernal goiters that must be appreciated to extract them safely:
    • Substernal goiter simply as those goiters that are associated with substernal extension such that the thoracic component requires mediastinal dissection to facilitate extraction
    • All substernal goiters require axial computed tomographic (CT) scanning to differentiate between the various subtypes
    • Such differentiation provides tremendously useful surgical information

#Arrangoiz #ThyroidSurgeon #ThyroidExpert #HeadandNeckSurgeon #CancerSurgeon #EndocrineSurgery #MultinodularGoiter #SubsternalGoiter #CASO #CenterforAdvancedSurgicalOncology

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