The Free Sign in morphea and other sclerosing disorders: A clue to the presence of early sclerosis?

Background: The Floating Sign is a histopathologic clue to the diagnosis of autoimmune sclerosing skin disorders such as morphea and interstitial granulomatous dermatitis (IGD). On the other hand, the "free-floating" sign has been associated with neoplasms, for example, dermatofibroma and interstitial mycosis fungoides. Herein, we report the Free Sign in sclerosing skin disorders.Methods: In a case-control study, we applied detailed histopathologic definitions of Floating Sign and Free Sign to assess their presence in morphea, IGD, and other sclerosing disorders.Results: Free Sign was present in most cases of morphea (46/55, 84%) and IGD (7/13, 54%) but not necrobiosis lipoidica (NL) (6/14, 42.8%) or sclerodermoid graft versus host disease (SGVHD) (2/7, 28.5%). The sensitivity and specificity of Free Sign for morphea versus other disorders was 84% and 56%, respectively. Floating Sign was not identified in most cases: NL (3/14, 21.4%), SGVHD (1/7, 14.2%), morphea (5/55, 9%), IGD (1/13, 7.7%). The diagnostic sensitivity of Floating Sign in morphea was 9%.Conclusions: The Free Sign was present in most cases of morphea in our series and may represent a clue to the presence of evolving sclerosis. Free Sign may be seen in other sclerosing disorders. Technical artifact is a potential cause of a false-positive Free Sign.