Presentation
Further evaluation of left ureteral dilation.
Patient Data
Split-bolus urogram with dilation of the left ureter and collecting system, with gradual fading of contrast-enhanced urine in the distal ureter.
Two small enhancing masses in the left rectus abdominis muscle below the umbilicus.
15 yr later after pregnancy
Very large bilobed mass arising from the left rectus abdominis muscle with mass effect on the lower abdomen/pelvis, with the posterior margin of the mass contacting the anterior L5 vertebral body.
Case Discussion
Small abdominal wall desmoid can be seen in retrospect on the CT urogram. It grew very rapidly and was detected during pregnancy, with pathology confirmed by ultrasound-guided biopsy (low-grade spindle cell neoplasm, consistent with desmoid-type fibromatosis). The mass continued to grow post-partum and the patient underwent tamoxifen therapy.
There are important associations with desmoid tumors growing during or after pregnancy, particularly in the rectus musculature. Although poorly understood, it is felt that a combination of abdominal wall trauma/stretching and hormonal and immunological factors play roles.