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Piffalls in diagnostic molecular pathology--significance of sampling error

E Heinmöller1, B Renke, K Beyser

  • 1Institute of Pathology, Klinikum Kassel, Germany. eheinmoeller@klinikum-kassel.de

Virchows Archiv : an International Journal of Pathology
|November 17, 2001
PubMed

Insights

Sampling errors in molecular pathology tests can lead to inaccurate results. Careful consideration of tissue characteristics and processing is crucial for reliable polymerase chain reaction (PCR) diagnostics.

Area of Science:

  • Molecular pathology
  • Diagnostic medicine
  • Genetics

Background:

  • Molecular diagnostic tests, particularly polymerase chain reaction (PCR), are integral to modern clinical medicine.
  • Challenges exist in tissue specimen analysis, where pathomorphological and processing factors can compromise test accuracy.
  • Potential for false-positive and false-negative results necessitates careful evaluation of tissue sampling strategies.

Purpose of the Study:

  • To investigate the impact of tissue sampling on the accuracy of widely used molecular diagnostic tests.
  • To systematically analyze how sampling methods influence results in B-cell clonality assessment, microsatellite instability (MSI) analysis, and mycobacterium tuberculosis detection.
  • To identify critical factors in tissue processing that contribute to diagnostic errors.

Main Methods:

  • Systematic investigation of tissue sampling in formalin-fixed, paraffin-embedded diagnostic specimens.
  • Comparison of results obtained from laser microdissection versus processing of entire tissue sections.
  • Application of standard polymerase chain reaction (PCR) protocols for molecular analyses.

Main Results:

  • False-positive results (pseudo-monoclonality) occurred in small biopsies and microdissected non-neoplastic tissues.
  • False-negative results (pseudo-stability) were observed in hereditary rectal adenoma cases when dysplastic subareas were not microdissected.
  • Failure to detect mycobacteria in formalin-fixed tissue sections, despite positivity in fresh-frozen material or after complete digestion.

Conclusions:

  • Sampling error is a significant source of false-positive and false-negative results in diagnostic molecular pathology.
  • Disease- and tissue-specific morphological features, including sample size, fixation type, and heterogeneity, must be considered for accurate molecular diagnostics.
  • Optimizing tissue sampling techniques is essential for improving the reliability of molecular diagnostic tests.

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