Fat Necrosis

Breast Core Biopsy: DDX of Calcifications

Fat necrosis in the breast parenchyma is a benign, non-suppurative inflammatory process resulting from injury to adipose tissue. The histologic appearance evolves over time, with calcifications typically being a later stage feature.

Histologic Features:

• Early/Acute Phase:

  • Disruption of adipocytes with release of neutral fat, forming cytoplasmic vacuoles and lipoid cysts (oil cysts) within the tissue.

  • Influx of acute inflammatory cells (neutrophils) and hemorrhage.

• Subacute/Organizing Phase:

  • Multinucleated giant cells (foreign body type) may be seen, often surrounding lipid droplets.

  • Lymphocytes and plasma cells contribute to the chronic inflammatory infiltrate.

  • Developing fibrosis around the necrotic fat and inflammatory cells.

• Late/Chronic Phase:

  • Predominance of fibrosis, which can appear as dense scar tissue, sometimes with architectural distortion.

  • Persistent oil cysts of varying sizes, often with calcified walls.

  • Residual inflammatory cells, particularly foamy macrophages and giant cells, may still be observed within and around the fibrotic areas.

• Hemosiderin deposition may be present from prior hemorrhage.

  

  Calcifications: These are a hallmark and can vary in morphology. They often appear as:

  • Dystrophic calcification: Irregular, coarse, amorphous deposits.

  • Rim-like or "eggshell" calcifications: Curvilinear calcifications outlining the walls of oil cysts.

  • Finer, punctate calcifications may also be present, which can sometimes mimic malignancy on imaging, necessitating biopsy for definitive diagnosis.

In summary, fat necrosis with calcifications is characterized by a spectrum of changes including necrotic fat, lipid-laden macrophages, multinucleated giant cells, fibrosis, and varying patterns of calcification.

This post created in collaboration with AI tools.