A Novel 2-Hour Method for Rapid Preparation of Permanent Paraffin Sections When Treating Melanoma In Situ with Mohs Micrographic Surgery

Abstract

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.