Immunohistochemically, the nodules were found to be positive for vimentin and actin, but negative for desmin and S-100 protein; these findings support the myofibroblastic nature of IM.
Immunocytochemistry (Ulex, factor VIII, JC/70A [CD31], PAL-E, BMA120, EN4, QBEnd10 [CD34], SMS actin) and ultrastructural studies showed no (marked) differences between different types of IMF.