Human sodium iodide symporter (hNIS) in fibroadenoma breast--a immunohistochemical study

Human sodium iodide symporter (hNIS), responsible for the active transport of iodine is an integral plasma membrane glycoprotein present in the thyroid cells and extrathyroid tissues like breast and salivary glands. If its functional form is unequivocally shown in benign or malignant breast tissues, then it may serve as a basis for diagnosis and treatment using radioactive iodine. With an aim to analyze the hNIS expression in a distinct benign breast condition of fibroadenoma, biopsy proven fibroadenoma tissues, normal non-lactating breast tissue and biopsy proven infiltrating duct carcinoma tissues were examined for hNIS expression using immunohistochemistry. Out of 20 biopsy proven fibroadenoma tissues, 19 (95%) showed positivity for hNIS protein and only one was negative. Of these 10% were mildly positive, 50% cases were moderately positive and 35% showed intense positivity. None of the control tissue obtained from reduction mammoplasty specimens or normal breast tissues samples (5 cms away from the tumor) were positive, hNIS was also intensely positive in 9 out of 10 (90%) infiltrating duct carcinoma tissues and moderately positive in one case. These preliminary results show that hNIS was present in high frequency as demonstrated by immunohistochemistry in fibroadenoma breast.