Increased mammary uptake on 111In pentetreotide scintigraphy

The normal scintigraphic features of 111In pentetreotide include uptake in the pituitary, thyroid, liver, spleen, kidneys, urinary bladder, gallbladder, and bowel. In premenopausal women, faint activity can be seen in the breasts. We present 2 cases of symmetrical, markedly increased mammary uptake. Our hypothesis to explain this pattern of uptake is an upregulation of the somatostatin type 2 receptor caused by high blood levels of estradiol during pregnancy. Estradiol levels during the menstrual cycle could therefore explain the variable degree of uptake commonly seen in premenopausal women.