Thyroid Follicular Hyperplasia Associated with Massive Extracellular Mucin Deposition

Extensive extracellular mucin deposition is a rare pathological thyroid condition with 6 cases described in literature so far. We report another case of a 67-year-old woman, discussing histopathological features, and review the literature. Our findings showed a diffuse mucin deposition in the stromal compartment of thyroid parenchyma. Histochemical stainings showed positivity for Alcian blue staining, but not for periodic acid-Shiff staining. Our case is peculiar because this mucin deposition was associated with benign nodular hyperplasia, in contrast with the other 6 reports, which described the same stromal alterations associated with benign or malignant thyroid tumors.