Ductal Carcinoma In Situ (DCIS)

• Neoplastic proliferation resembling small ducts with expanded duct and acinar structures
• Myoepithelial cell layer is intact surrounding the neoplastic proliferation (non-invasive tumor)
• Typically express E-Cadherin
• Bilateral in 10-20% of cases
• Detected by mammography (not clinically evident)
• Represents 15-30% of neoplasms identified in screening populations
• Typically identified by abnormal calcification, sometimes as abnormal densities

Comedo DCIS

• High grade pleomorphic nuclei
• Central necrosis

Non-comedo DCIS

• Lacks either high grade nuclei or central necrosis
• Subtypes/patterns
  • Solid DCIS
  • Micropapillary DCIS
  • Cribiform DCIS
• DCIS grading
  • Low-grade DCIS
    • 1%/year risk of developing an invasive carcinoma
  • Intermediate-grade DCIS
  • High-grade DCIS

Paget Disease

• Nipple manifestation of disease (1-4% of cases) – looks like eczema on the nipple
• Tumor cells extend into the epidermis of the skin overlying the nipple from underlying DCIS within the ductal system of the breast.
• 50-60% of women will have an underlying palpable mass
  • Vast majority will have an invasive carcinoma (often ER neg./Her-2 pos.)
  • Women without a palpable mass will usually only have DCIS

Photomicrographs

References

Kumar, Vinay, Abul K. Abbas, and Jon C. Aster. Robbins and Cotran Pathologic Basis of Disease. Ninth edition. Philadelphia, PA: Elsevier/Saunders, 2015.