Nipple shadows

Last revised by Mostafa Elfeky on 13 Aug 2023

Nipple shadows refer to the silhouettes of the nipples on frontal chest radiographs, which may mimic solitary pulmonary nodules (SPNs).

Nipple shadows are apparent on ~7.5% (range 3.5-11%) of frontal chest x-rays 1.

It has been proposed by Miller et al. that solitary pulmonary nodules that reach some or all of the following criteria be considered nipple shadows 2:

  • 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 the 5th and 6th ribs anteriorly
    • female: at the inferior aspect of the breast shadow
  • were not present on a very recent film
  • prominent nipples may be visible on a lateral projection

However, if there is doubt whether a nodular opacity represents a nipple shadow or not, a repeat chest x-ray with nipple markers should be performed 4, albeit at a financial cost and further radiation dose to the patient.

There is always the rare occurrence of a real solitary pulmonary nodule being overshadowed by a nipple shadow.

On chest radiograph the following features are present:

  • nipple shadows are nodular opacities that are consistent in shape, size and position 1,2:
    • oval or round
    • 5-15 mm in diameter
    • between the 9th and 10th ribs posteriorly or the 5th and 6th ribs anteriorly
  • tend to have incomplete margins due to their attachment to the chest wall 4

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4
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