Nipple shadows in chest xray characteristically have a sharp

Miller et al proposed that solitary pulmonary nodules that reach some or all of the following criteria can be considered nipple shadows :Bilateral and symmetric"fuzzy" margins or radiolucent "halo"Sharp lateral border and poorly defined medial border (may be present only on pa projections 3)Nodules are in a characteristic position:Male: between fifth and sixth rib anteriorlyFemale: at the inferior aspect of the breast shadowWere not present on a very recent filmProminent nipples may be visible on a lateral projectionHowever, if there is doubt repeat chest x-ray with nipple markers should be performed.(Ref: Miller WT, Aronchick JM, Epstein DM et-al. The troublesome nipple shadow. AJR Am J Roentgenol. 1985;145 (3): 521-3.)