Surface Decalcification

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The page below is a sample from the LabCE course Tissue Decalcification for Paraffin Processing. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Surface Decalcification

When the presence of calcium was not expected, such as in kidney, lung, prostate, or skin tissue but is revealed during trimming, a paraffin-embedded tissue can be "surface decalcified" prior to microtomy. Also, bone that has already been decalcified may need more time in decal solution, and surface decal may also be employed in such cases. Surface decalcification allows the decalcifier to penetrate a small distance into the block and dissolve the calcium.
Steps for surface decalcification of paraffin-embedded tissue blocks:
  1. Coarse face the tissue block to expose the entire tissue (if possible).
  2. Place the tissue block in the preferred decalcifier (typically HCl) for 30-60 minutes.
  3. Rinse the block in water and blot dry.
  4. Place on ice.
  5. Section as usual, but remember that only the surface was decalcified. Deeper sections may need to be decalcified.