Electron Microscopic Study Using Formalin-fixed, Paraffin-embedded Material, with Special Reference to Observation of...

Area of Science:

• Diagnostic Pathology
• Electron Microscopy (EM)
• Histopathology

Background:

• Diagnostic pathology practice often involves specimens not fixed under ideal conditions for electron microscopy (EM).
• Traditional EM requires specific fixation protocols, limiting its application to archival or non-optimally preserved samples.

Purpose of the Study:

• To describe and evaluate the utility of ultrastructural studies using routine formalin-fixed and paraffin-embedded (FFPE) material.
• To demonstrate the feasibility of EM analysis on FFPE tissue sections, including those processed with specific stains.

Main Methods:

• Utilized formalin-fixed and/or paraffin-embedded tissue samples for ultrastructural examination.
• Investigated the preservation of fine morphology and particulate structures (neuroendocrine granules, microbes) in paraffin sections.
• Employed pre-embedding techniques on paraffin sections stained with Grimelius, Grocott, or immunostaining (DAB) for EM evaluation.

Main Results:

• Fine morphologic preservation was often acceptable, particularly from small tissue cubes extracted from paraffin blocks.
• Particulate structures, including neuroendocrine granules and microbes, were consistently observed in paraffin sections.
• Stained paraffin sections (Grimelius, Grocott, DAB) were successfully adapted for EM evaluation using pre-embedding methods.

Conclusions:

• FFPE tissues are a viable resource for ultrastructural pathology, offering acceptable morphologic detail.
• This approach allows for targeted EM analysis of focal lesions and retrospective studies of rare conditions from archival material.
• Provides pathologists a practical method for identifying pathogens and analyzing rare ultrastructural findings in FFPE samples.