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Updated: Jun 30, 2026
The Cutting and Floating Method for Paraffin-embedded Tissue for Sectioning
Published on: September 5, 2018
A novel 2-hour method for rapid preparation of permanent paraffin sections when treating melanoma in situ with mohs
Raj Mallipeddi1, Jeff Stark, Xian-Jin Xie
1Dermatological Surgery and Laser Unit, St John's Institute of Dermatology, St Thomas' Hospital, London, UK.
Background:
Distinguishing sun-induced melanocyte atypia from residual melanoma in situ (MIS) can be challenging, particularly when working with frozen sections. Immunostains such as melanoma-associated antigen recognized by T cells (MART-1) can assist, but paraffin sections provide an optimal means of analyzing melanocyte morphology.
Objective:
To verify the effectiveness of a 2-hour paraffin processing technique that uses microwave technology in the preparation of MIS sections.
Methods:
Twelve MIS debulk specimens were divided into 4 pieces with each piece processed 1 of 4 ways: our 2-hour paraffin technique with hematoxylin and eosin (H&E), conventional 24-hour paraffin processing with H&E, frozen sections with H&E, and frozen sections with MART-1 immunostaining. A Mohs surgeon and a dermatopathologist compared all specimens in a blinded fashion using a 3-point ranking scale to assess ease of visualizing normal melanocytes, ease of visualizing abnormal melanocytes, and overall ability to adequately visualize epidermal and dermal structures.
Results:
A nonparametric signed rank test indicated no significant differences between our microwave technique and conventional paraffin processing in all 3 criteria (p=.29, .63, .75, respectively). Our microwave technique was significantly better than frozen H&E sections for all 3 criteria (p=.046, .004, .005, respectively).
Conclusion:
This rapid microwave tissue processing technique is comparable with conventional paraffin section processing.
