Calcium oxalate crystals in breast biopsies. The missing microcalcifications

Area of Science:

• Pathology
• Crystallography
• Breast Imaging

Background:

• Mammography and specimen radiography detect breast calcifications.
• Standard histologic stains like H&E and von Kossa may not identify all calcifications.
• Calcium oxalate crystals present a diagnostic challenge in breast biopsy analysis.

Purpose of the Study:

• To investigate the incidence of calcium oxalate crystals in breast biopsies.
• To determine the utility of polarized light microscopy for identifying these crystals.
• To explain discrepancies between imaging and histological findings of microcalcifications.

Main Methods:

• Review of 153 needle-localization breast biopsies using polarized light microscopy.
• Histologic analysis with H&E, von Kossa, alizarin red, and silver nitrate/rubeanic acid stains.
• Analytical electron microscopy (energy-dispersive x-ray analysis and electron diffraction) on select cases.

Main Results:

• Birefringent crystals, suggestive of calcium oxalate, were found in 19 cases (12.4%).
• Standard H&E staining identified microcalcifications in only 16 of these 19 cases.
• Electron microscopy confirmed calcium oxalate monohydrate in a case lacking typical microcalcifications on H&E.

Conclusions:

• Discrepancies in microcalcification detection between imaging and H&E histology can be due to calcium oxalate crystals.
• Polarized light microscopy is crucial for identifying these oxalate crystals in breast biopsies.
• Recommended use of polarized light microscopy and specific stains when typical microcalcifications are absent on H&E sections.