This young female patient noticed this mass which slightly grew over two years, and only slightly during pregnancy.
The relationship of desmoids to pregnancy is complex and poorly understood. It is suspected that a combination of birth-related trauma related to muscular/fascial stretching and the hormonal and immunological changes of pregnancy play key roles. There is an increased risk of desmoid tumors arising in and around pregnancy, and (interestingly) they most commonly occur in the right rectus abdominis muscle as in this case 1. They often regress after pregnancy, and many tumors (~50%) respond to the anti-estrogenic drug tamoxifen.