Lymphocytic infiltrate with predominance of IgG4-positive plasma cells and CD4+ T lymphocytes;

Storiform fibrosis or fibrosis consisting of proliferating spindle-shaped cells around infiltrating lymphocytes;

Obstructive phlebitis;

Refers to a carcass wheel pattern with a sometimes spiral center, and bands of fibrosis emanating from it with an irregular tangled weave somewhat resembling that of a straw mat.