Table 4.

IgG4 in serum, in thyroid tissue and % IgG4 with immunohistochemistry in Riedel’s thyroiditis

Case	Histopathology	S-IgG4	Tissue IgG4	Tissue IgG4/IgG
1	Lymphocytes, granulocytes, scarlike fibrosis, and extrathyroideal engagement	NA	Yes	50%
2	Fibrosis, no visible thyroid cells	NA	NA	NA
3	Massive infiltrates of inflammatory cells, extrathyroidal engagement	Neg	NA/FNA	NA/FNA
4	Inflammatory cells, fibroblasts, and no thyroidal tissue	Neg	NA/FNA	NA/FNA
5	Fibrosis, lymphocytes, and extrathyroideal engagement	Neg	Yes	2%
6	Inflammatory cells, extrathyroideal engagement	Neg	Yes	13%

NA not available, FNA fine needle aspiration