Scottish researchers recently treated two women in whom
the initial symptoms were breast pain and neither woman
associated the pain with DCS. The researchers, who had not
seen similar cases in more than 200 cases of DCS, postulate
that breast pain may be an under-recognized manifestation of
DCS.
 Breast pain presented in a 34-year-old female 90 minutes
  after completing a 32-minute dive to 39 meters; she made
  two decompression stops on the way up. The pain failed to
  resolve and was followed by pain in the right shoulder. After
  successful chamber treatment, she recalled two previous episodes
  in which she had severe breast pain after completing
  non-decompression dives, attributing her symptoms to the
  physical restriction of her dry suit or clambering into the dive
  boat. Once the pain had been so severe that she was unable
  to tolerate a car seat belt during the drive back from a dive.
 An hour after a 29-year-old female completed her third
  dive in two days, she developed breast discomfort so severe
  that she was unable to tolerate her bra. She was given oxygen
  on the dive boat, and she was treated successfully in a chamber
  for DCS.
 Both women were diving in their usual dry suits. Both
  received what might be regarded as undeserved decompression
  illness despite unremarkable dives with appropriate
  decompression stops. Both were subsequently shown to have
  significant patent foramen ovale, which is associated with
  an increased risk of decompression illness. It is impossible
  to prove that the breast symptoms were definitely due to
  DCS; however, nitrogen bubbles may have caused lymphatic
  obstruction in breast tissue, or the constriction of breast tissue
  in a tight dry suit, by restricting lymph flow, might make
  this presentation likely.
Undersea and Hyberbaric Medical Journal 2(106, Vol. 33, Nn, 2)
  “Decompression illness presenting as breast pain.” A.J. Trevetti, C.
  Sheehan, R. Forbes, Orkney Hyperbaric Chamber, Orkney, Scotland.