Right Femoral Pseudoaneurysm Versus Inguinal Abscess: Progressive Inguinal Mass Following Blunt Trauma

When evaluating a patient with inguinal swelling following blunt trauma, maintaining a broad differential diagnosis is crucial, especially when laboratory and imaging findings do not correlate with the patient's history. An important consideration is the choice of imaging modality to assess progressively worsening inguinal pain and swelling. A 21-year-old healthy female presented to the ED with a progressively enlarging mass in the right inguinal region following traumatic injury. She had undergone two prior evaluations by an OB-GYN, with recommendations for acetaminophen and NSAIDs, which provided no relief. The mass had increased in size relative to her discomfort, causing difficulty ambulating. On initial presentation, she was afebrile but tachycardic. Physical examination revealed significant right-sided vaginal edema extending throughout the inguinal region without overlying integumentary changes, abrasion, laceration, or ecchymosis. Laboratory evaluation was remarkable only for leukocytosis. Advanced imaging identified a right inguinal pseudoaneurysm of indeterminate vascular origin with a surrounding hematoma measuring 4.3 × 3.7 cm. The patient was subsequently hospitalized for vascular surgery consultation. Vascular ultrasonography was performed to further characterize the lesion, revealing a vascularized region in the right groin measuring 2.07 × 1.17 cm, although a pseudoaneurysm could not be ruled out. Ultimately, the patient was taken to the operating room, where an abscess with purulent drainage was identified. Sonographic imaging may have limitations in differentiating a hematoma or pseudoaneurysm from an abscess due to similar anechoic to hypoechoic findings. This patient presented with a progressively worsening inguinal mass unresponsive to acetaminophen and ibuprofen, with overlying erythema. While ultrasonography is a logical initial imaging modality to rule out a simple abscess, the presence of Doppler flow should prompt consideration of further imaging with CT angiography. CT angiography provides a detailed evaluation of vascular involvement and associated pathology, and it aids in treatment planning, including decisions regarding medical management versus surgical intervention.