cell blocking

• Cell blocks


  Cytologic preparations that are processed as paraffin embedded blocks in a manner comparable to formalin-fixed paraffin-embedded tissue in surgical pathology
• Cell blocks


  • Introduced in 1896 using colloidin embedding medium
  • Accepted in 1940s
  • CB techniques have evolved
  • Basic protocol similar in all techniques
• Cell block application


  Can be used on any nongynecologic specimen, most commonly: Serous effusions, Pelvic/abdominal washes, Fine needle aspirations, Liquid based specimens
• Procedure for cell block should be applied if there is visible sediment after being centrifuged
• Cell block


  • Prepared for IHC and molecular studies
  • Increases the cellular yield and improves diagnostic accuracy
• Plasma thrombin technique


  1. Cell button added to plasma and thrombin

  2. Cell material collects in clot
• Agar or other gelatin techniques


  1. Concentrated sediment supported in agar or histogel

  2. Cell pellet formed then processed in paraffin
• Collodion bag technique


  1. Concentrated sediment supported in agar or histogel

  2. Cell pellet formed then processed in paraffin
• Tissue clot technique


  1. Allow clot to form in lumen of needle tip

  2. Clot transferred to formalin

  3. Prevents loss of diagnostic material
• Shandon™Cytoblock™ method


  1. Uses cytocentrifugation to concentrate cells in cytospin

  2. Kit of cell block cassettes and reagents
• Sedimentation cell block technique


  1. Transfer material to centrifuge tube

  2. Spin down to achieve a concentrated cell button

  3. Centrifuge set at 2400 RPM for five minutes

  4. Pour off supernatant

  5. Add buffered formalin

  6. Let material set in tube; 30-60 minutes

  7. Remove hardened cell button with a metal spatula

  8. The button placed on histology tissue paper that has been moistened with buffered formalin
• Cell blocks cut at 8μm
• If IHC needs to be performed it is noted on the QC sheet so appropriate number of sections can be cut and ready for IHC stains
• Cassette is checked by two cytotechnology lab technologists for proper labeling – Quality Assurance
• Cell block placed in formalin for at least six hours, documented on requisition with time stamp
• Pap test


  • Thin Prep, Papanicolaou stain
  • Cell block, Hematoxylin and Eosin stain
• Urine; bladder washing


  • Thin Prep: Papanicolaou stain
  • Cell block: Hemotoxylin & Eosin stain
• a bloody urine cannon be used for cell blocking

  true or false

  false