Subcutaneous abdominal wall masses: radiological reasoning

OBJECTIVE: A 36-year-old woman presented to her primary care physician with right lower abdominal pain. Her physician subsequently requested a CT to rule out appendicitis. Contrast-enhanced CT was performed and revealed no evidence of appendicitis but showed two subcutaneous ovoid soft-tissue masses anterior to the rectus sheath in the upper pelvis. Pelvic MRI confirmed the two masses, which showed mild enhancement. The objective of this article is to discuss a diagnostic approach to subcutaneous soft-tissue masses in the abdominal wall. Diagnosis was endometriosis of the abdominal wall. CONCLUSION: Integrating salient imaging findings with clinical history is crucial when approaching the diagnosis of subcutaneous soft-tissue masses. The diagnosis of endometriosis should be entertained when soft-tissue masses are seen in the distribution of a cesarean section scar in a woman of reproductive age. Pain, particularly with a cyclic pattern, is highly suggestive of endometriosis. If endometriosis is suspected on CT or ultrasound, MRI can be performed for further evaluation. Definitive diagnosis is made with biopsy. Because subcutaneous nodules are so amenable percutaneous biopsy, imaging features, although of interest, are somewhat ancillary to the diagnostic workup.