Classification of ductal carcinoma in situ (DCIS)

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The new pathological classification of DCIS (ductal carcinoma in situ) is based on cytonuclear atypia, degree of necrosis, size, and distance from margin/architecture. Low and intermediate grades DCIS require cytologic, architectural and size criteria to be met but high-grade DCIS requires only cytologic criteria; this is as follows:

  • low grade
    • round, regular to mildly irregular nuclei up to 2-3 times the size of a red blood cell
    • no comedo necrosis
  • intermediate grade
    • round, regular to mildly irregular nuclei up to 2-3 times the size of a red blood cell
    • substantial comedo necrosis
  • high grade
    • pleomorphic nuclei  more than 3 times the size of a red blood cell
    • substantial comedo necrosis usually present, but not required for the diagnosis