Excision of selected skin tumours using Mohs' micrographic surgery with horizontal paraffin-embedded sections

Histological interpretation of frozen sections made during Mohs' micrographic surgery may be difficult, depending on the morphological and staining characteristics of the tumour and on the nature of the associated inflammatory infiltrate. We have employed an adaptation of micrographic surgery in which horizontal, formalin-fixed, paraffin-embedded sections were used to improve histological assessment in the excision of 18 non-melanoma skin tumours in which frozen sections had been or were likely to be unsatisfactory. We describe our experience of this method in the management of squamous cell carcinomas (11), extramammary Paget's disease (two), microcystic adnexal cell carcinomas (two), dermatofibrosarcoma protuberans (two), and primary cutaneous neuroendocrine carcinoma (Merkel cell carcinoma) (one). The use of horizontal paraffin-embedded sections lengthens the duration of the procedure but facilitates accurate assessment of histological sections in selected tumours.