Abdominal Incision and Injection Sites



Abdominal Incision and Injection Sites


Michael P. Federle, MD, FACR

Harpreet Dhatt, BA





Key Facts


Imaging



  • Injection granulomas



    • Most common in subcutaneous fat of buttocks


    • Soft tissue or calcific density lesions


  • Injection site fluid or gas collection



    • Common in subcutaneous tissue of anterior abdominal wall (insulin, heparin, etc.)


  • Diabetic lipodystrophy



    • Insulin-dependent diabetic patients may develop atrophy or hypertrophy of fat at injection sites


    • Injection site lipohypertrophy (hypertrophy of fat and fibrous tissue)


  • Injection or incision site hematoma or seroma



    • May be misinterpreted as neoplastic mass


  • Injection or incision site abscess



    • Gas bubbles and enhancing wall with mass effect


  • Keloid (hypertrophic scar)



    • Overgrowth of tissue at site of healed skin injury


    • 15x increased incidence in African-Americans


  • Calcified or ossified scar



    • May resemble rib, complete with cortex and medulla


    • Within linea alba after upper abdominal incision


  • Endometrial implantation in abdominal incision



    • Follows cesarean section or other uterine surgery


    • Cyclical pain at incision site with menstruation


  • Tumor implantation in incision sites



    • Can occur after “open” or laparoscopic incisions


    • Usually resembles primary tumor


Top Differential Diagnoses



  • Desmoid


  • Abdominal wall neoplasms






(Left) Plain film radiograph shows rounded and linear calcified injection sites image within the subcutaneous fat overlying the buttocks. (Right) Axial CECT in the same patient shows the subcutaneous location and characteristic appearance of injection site granulomas image.






(Left) Plain film radiograph shows rounded calcifications image that overlap the lower abdomen. Some of these are lateral to the descending colon and close to the skin, establishing their extraabdominal location. (Right) Axial NECT in the same patient shows heavily calcified injection sites image in the subcutaneous tissues over the buttocks. Renal failure may have contributed to the deposition of so much calcium in these lesions.



TERMINOLOGY


Definitions



  • Lesions in abdominal wall or torso resulting from incision or injection sites; may be misinterpreted as other pathologic conditions


IMAGING


General Features



  • Best diagnostic clue



    • CT showing exact site and morphology of lesions


  • Size



    • Varies by etiology


  • Morphology



    • Varies by etiology


Imaging Recommendations



  • Best imaging tool



    • CT


Radiographic Findings

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Jun 8, 2016 | Posted by in GENERAL RADIOLOGY | Comments Off on Abdominal Incision and Injection Sites

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