Infantile digital fibromatosis-like tumour (inclusion body fibromatosis) of adulthood: report of two cases with ultrastructural and immunocytochemical findings.

Two adult cases of a cutaneous lesion indistinguishable from typical infantile digital fibromatosis are added to the unique similar case so far reported in adulthood. The immunocytochemical localization of vimentin and muscle actin in the proliferating cells confirms their myofibroblastic nature and establishes closer relationships between the adult and the infantile variants of this entity. These two variants, however, appear to be clinically different, since all the adult cases were extradigital and did not recur after surgical excision. The term inclusion body fibromatosis underlines the histological hallmark of the lesion and should be used to identify this entity in place of recurrent infantile digital fibromatosis which does not seem any longer appropriate.