Dermatofibrosarcoma protuberans: dealing with slow Mohs procedures employing formalin-fixed, paraffin wax-embedded tissue in a busy diagnostic laboratory.

Dermatofibrosarcoma protuberans (DFSP) is a relatively uncommon tumour that arises in the dermis and underlying soft tissue. Surgical removal is the preferred treatment, with relatively wide clearance margins of 3 cm or more. Slow Mohs procedures are often employed successfully to treat patients with such tumours. Slow Mohs procedures offer the benefit of improved cure rates and maximal tissue conservation. However, dealing with such tissue successfully presents the laboratory with a host of technical problems. This report advocates a set protocol to follow for slow Mohs, based on the experience acquired from dealing with 37 cases of DFSP over a 12-year period. The report establishes the benefits of slow Mohs paraffin wax-embedded tissue over frozen sections in terms of improved morphology, tissue preservation and immunocytochemical labelling with anti-CD34.