Fig. 4From: Diagnostic pitfall of thyroid fine-needle aspiration induced fibrosis: follicular adenoma mimicking medullary thyroid carcinoma in frozen sectionSpecial stain and immunohistochemical features of the mass. a Congo Red staining of the section did not reveal any apple-green birefringence under polarized light microscopy (original magnification, × 400). b The homogenous eosinophilic materials stained blue with Masson trichrome stain (original magnification, × 100). The tumor cells showing immunoreactivity for thyroglobulin (c); original magnification, × 100) and TTF-1 (d); original magnification, × 100). The tumor cells did not express immunoreactivity for synaptophysin (e); original magnification, × 100) or calcitonin (f); original magnification, × 100)Back to article page