Kryoschnitte

Kryoschnitte, or frozen sections, are thin tissue sections prepared from rapidly frozen specimens for immediate microscopic evaluation. They are commonly used for intraoperative consultation, margin assessment in cancer surgery, and rapid preliminary diagnosis in various medical fields.

Process and technique: After tissue collection, a small sample is oriented and embedded in a cryomount medium such as OCT. The sample is rapidly snap-frozen in a cryostat at cold temperatures, typically between −20 and −30 °C. The frozen block is cut with a microtome inside the refrigerated chamber to produce sections about 5–20 micrometers thick. Sections are mounted on glass slides, quickly stained (often with hematoxylin and eosin or rapid stains), and examined by a pathologist, providing a preliminary assessment within minutes.

Comparison with paraffin sections: Kryoschnitte offer faster turnaround than formalin-fixed, paraffin-embedded sections but may show ice-crystal artifacts and less optimal preservation of certain cellular details. Some tissues freeze poorly, leading to artifacts such as cracking or distortion. For comprehensive immunohistochemical or molecular analyses, paraffin sections or other fixed specimens are often preferred.

Advantages and limitations: The primary advantages are speed and the ability to obtain diagnostic information during surgery, which can influence immediate clinical decisions. Limitations include potential artifacts, lower architectural detail, and variability in staining quality. The suitability of a frozen section depends on tissue type and the clinical question.

Applications and context: Kryoschnitte are widely used in intraoperative pathology, tumor margin assessment, dermatopathology, neuropathology, and research settings. They require trained personnel, appropriate equipment, and adherence to biosafety and quality control standards.