[Atypical scleromyxedema with a granulomatous histological pattern and delayed sclerosis].

Background: Papular mucinosis is characterised by primary mucin deposition in the dermis. The classification distinguishes between the localised form and the systemic form, which alone can result in complications, but this classification occasionally proves to be inadequate. Herein we report the progression of papular mucinosis, initially atypical due to the absence of cutaneous sclerosis and of misleading granulomatous histological features, which subsequently developed into characteristic scleromyxedema.
Patients and Methods: A 55-year-old male developed a rash comprising countless acral papules. Several biopsies were necessary before a diagnosis of papular mucinosis was made, due to the initial granulomatous appearance at histology. Tests showed monoclonal immunoglobulin of indeterminate significance, but, due to the absence of cutaneous sclerosis, we were able to conclude on typical localised papular mucinosis. Two years later, extensive sclerotic induration of the skin appeared and the diagnosis was modified to one of scleromyxedema. Treatment with intravenous immunoglobulins was given and proved efficacious, but relapse occurred on discontinuation of the therapy.
Discussion: Papular mucinosis is a rare disease of unknown physiopathology. The disease classification distinguishes between the localised and systemic forms, but it occasionally proves to be inadequate. Our case suggests a continuum between the localised and systemic forms of the disease. Further, the initial biopsies of acral papules in our patient had a misleading granulomatous appearance, as has been reported numerous times for the systemic forms. This granulomatous histological variant thus appears to constitute a diagnostic criterion for scleromyxedema.
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