Background: Some cases of dermatofibrosarcoma protuberans (DFSP) do not protrude above the skin.
Objectives: To assess the prevalence of these DFSPs and further to describe their presentation and course.
Methods: One hundred and forty-three patients were retrospectively collected. They were asked to complete a standardized questionnaire indicating the history and appearance of the DFSP from the first skin changes identified to the time of diagnosis.
Results: Eighty-one DFSPs were described as protuberant ab initio, and 62 as initially nonprotuberant (npDFSP). The latter remained at this stage for a mean period of 7.6 years. Twenty-nine per cent of npDFSPs were 'morphoea-like', 19% were 'atrophoderma-like' and 42% were 'angioma-like'. Age at diagnosis was similar for both initial presentations. npDFSPs were most often misdiagnosed by physicians.
Conclusions: Nearly half the patients first identified their early DFSP-related skin changes as patches. Both this frequency and the long duration at this preprotuberant stage should prompt dermatologists to consider the diagnosis of DFSP earlier, in order to make surgical treatment easier.