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ESSENTIAL INFORMATION

Key Differential Diagnosis Issues
- Although clinical exam may diagnose many common groin masses (particularly hernias), imaging often necessary for accurate diagnosis, particularly with atypical masses - US 1st-line modality for vascular and male reproductive (e.g., cryptorchidism, varicocele) abnormalities - CT and US are best options for diagnosis of groin hernias - US offers advantage of being able to image patients in different positions (such as standing) or during Valsalva to increase chance of visualizing hernias - CT or MR appropriate for suspected musculoskeletal lesions, such as bursitis or bone tumor
Helpful Clues for Common Diagnoses
- Inguinal Hernia - Divided into direct or indirect subtypes based on relationship to inferior epigastric vessels - Direct hernias arising anteromedial to inferior epigastric vessels - Indirect hernias arising superolateral to inferior epigastric vessels - Typically located anterior to horizontal plane of pubic tubercle with no significant mass effect on femoral vein - Hernia sac can contain omental fat, bowel, bladder, appendix, and other pelvic structures - Usually diagnosed on clinical exam, but diagnosis easily confirmed on both CT and US
- Femoral Hernia - Almost always diagnosed in older women - Extends medial to femoral vein and inferior to inferior epigastric vessels with mass effect on femoral vessels - Hernia sac located posterior and lateral to pubic tubercle - Highest strangulation rate among groin hernias (25-40%)
- Groin Hematoma - Most often encountered after groin catheterization and should prompt search for underlying pseudoaneurysm or active extravasation, though also commonly seen in setting of inguinal or scrotal surgery and anticoagulation - May demonstrate active extravasation on CECT in setting of active bleeding
- Groin****Pseudoaneurysm - Most often encountered after groin catheterization (3% of cases following cardiac catheterization) - US demonstrates cystic structure connecting to femoral artery with internal yin-yang biphasic flow - Often treated with compression or thrombin injection
- Groin Arteriovenous Fistula - Abnormal communication between artery and vein, which is most often iatrogenic and related to groin catheterization - Direct communication between femoral artery and vein may not be readily visible on US, but secondary findings can help make diagnosis (increased diastolic flow in artery, arterialized flow in vein, turbulent flow with soft tissue color bruit artifact)
- Inguinal Lymphadenopathy - Inguinal regions are common site of lymphadenopathy in many malignancies and systemic disease - Lymph nodes are usually mobile and easily distinguished from hernia based on clinical exam alone, although imaging can easily make distinction in difficult cases
- Varicocele - Can extend into inguinal canal (as can hydrocele) and may be thought to represent mass on clinical exam - US demonstrates tangle of mildly dilated vessels (≥ 3 mm) with slow flow and enlargement during Valsalva - May be seen on CT with tangle of dilated vessels, which communicate with dilated ipsilateral gonadal vein - Most often found on left side, as isolated right-sided varicocele should raise concern for obstructing mass in abdominal or pelvic cavity
- Spermatic Cord Lipoma - Can clinically mimic hernia without true hernia being present and frequently mistaken for inguinal hernia on CT/MR - Extremely common incidental finding at surgery (seen in 20-70% of all inguinal hernia repairs) - Fat-containing lesion in inguinal canal without any true connection to intraperitoneal fat, though differentiating spermatic cord lipoma from small inguinal hernia on any imaging modality can be extremely difficult to do with accuracy
- Mesh Hernia Repair (Mimic) - Mesh plugs used during inguinal hernia repair can appear focal and mass-like and potentially mimic lymph node or other mass - Ipsilateral spermatic cord often thickened as well due to surgical manipulation
Helpful Clues for Less Common Diagnoses
- Cryptorchidism - Common congenital anomaly found in up to 4% of term male babies, which can be associated with increased risk of infertility and malignancy later in life - Undescended testicle (usually are found in vicinity of groin/inguinal canal) can be palpated on physical exam in vast majority of cases - US or MR are 1st-line imaging modalities with MR offering ability to identify intraabdominal testicle
- Groin Aneurysm - True atherosclerotic aneurysms of common femoral artery are rare and often associated with aneurysms elsewhere (especially aorta and popliteal arteries)
- Iliopsoas Bursitis - Focal, teardrop-shaped collection of fluid immediately anterior to hip joint typically associated with hip joint pathology (such as degeneration, infection, etc.)
- Bone Tumor - Any benign or malignant primary bone tumor arising from pubic rami or hip can present as groin mass with CT and MR best initial modalities for evaluation
- Inguinal Abscess - Focal, rim-enhancing fluid collection with surrounding stranding and edema in patient with clinical signs and symptoms of infection
Helpful Clues for Rare Diagnoses
- Canal of Nuck Hydrocele - Extremely rare condition caused by congenital incomplete obliteration of canal of Nuck (fold of parietal peritoneum that extends into inguinal canal and toward labia majora) - Typically diagnosed in female children (and extremely rarely in female adults) as painless, fluctuant swelling in groin - Unilocular cystic mass in groin extending along inguinal canal toward labia (without any solid or soft tissue component and usually simple in appearance)
- Inguinal Canal Endometriosis - Endometriosis can rarely extend into inguinal canal (usually on right) - Imaging appearance akin to endometriosis elsewhere with pain groin mass varying with menstrual cycle - Incomplete closure of canal of Nuck may provide pathway for endometriosis to extend into groin
- Liposarcoma - Fat-containing mass typically with solid, soft tissue components, septations, and other complexity (and with variable amounts of internal fat depending of degree of differentiation) - Primary spermatic cord liposarcomas arise below superficial ring without extension superiorly into peritoneum - Other primary sarcomas of spermatic cord (leiomyosarcoma, rhabdomyosarcoma, etc.) are also possible but far less common - Retroperitoneal liposarcomas with secondary extension downward into inguinal canal are much less common but can clinically mimic groin hernia
- Metastases to Inguinal Canal - Metastases to inguinal canal are extraordinary rare, but most common with prostate cancer, pancreatic cancer, melanoma, rhabdomyosarcoma, and pseudomyxoma peritonei

References

Selected References

Images

Selected Images

Inguinal Hernia Coronal NECT shows a large right inguinal hernia containing loops of small bowel without evidence of obstruction. In most cases, inguinal hernias can be palpated and diagnosed clinically.

Femoral Hernia Axial CECT shows the characteristic position of a femoral hernia with a knuckle of bowel identified medial to the femoral vessels. Note the characteristic compression of the adjacent femoral vein .

Groin Hematoma Coronal CECT shows a large right groin hematoma with massive active extravasation of contrast . This patient had recently undergone a complicated right groin catheterization with subsequent severe blood loss.

Groin Hematoma Longitudinal US in a patient with groin swelling after catheterization shows a large, complex hematoma with internal echoes and mixed echogenicity.

Groin Pseudoaneurysm Color Doppler US in a patient who had undergone recent groin catheterization shows the characteristic features of a pseudoaneurysm with a yin-yang pattern of internal color flow. Note that the pseudoaneurysm does appear to connect with the adjacent femoral artery .

Groin Pseudoaneurysm Axial CECT in a patient with a history of IV drug abuse shows a large, mycotic pseudoaneurysm of the right common femoral artery with surrounding fat stranding and edema.

Groin Arteriovenous Fistula Axial CECT in a patient with swelling of the right groin after groin catheterization shows asymmetric enlargement and enhancement of the right common femoral vein , while the contralateral left femoral vein is not yet opacified. This constellation of findings should rise strong concern for an AV fistula.

Inguinal Lymphadenopathy Axial CECT shows an enlarged left inguinal lymph node , found to represent posttransplant lymphoproliferative disorder in this patient with a history of renal transplant.

Varicocele Sagittal color Doppler US shows a classic tangle of tortuous vessels within the upper part of the scrotum. Flow and vessel dilation are accentuated by Valsalva maneuver, characteristic of a varicocele.

Mesh Hernia Repair (Mimic) Axial CECT shows the characteristic appearance of a mesh plug related to prior inguinal hernia repair. This is a classic appearance, which should not be confused for pathology.

Cryptorchidism Axial T2 FS MR in a patient with an undescended left testicle shows the T2-bright testicle in the left pelvis. MR is the best modality for identifying an undescended testicle with an advantage over US for identifying testicles in the abdominal/pelvic cavities.

Iliopsoas Bursitis Axial CECT shows the classic appearance of iliopsoas bursitis with a fluid collection anterior to the right hip displacing the neurovascular bundle anteriorly.

Liposarcoma Axial NECT shows a complex, fat-containing mass in the left inguinal canal, found at resection to represent a primary spermatic cord liposarcoma.

Liposarcoma Coronal CECT shows a fat-containing mass with minimal internal complexity extending from the right lower quadrant into the right inguinal canal. This represents a primary retroperitoneal liposarcoma with secondary extension into the inguinal canal.

Additional Images

Inguinal Lymphadenopathy Axial CECT shows bilateral pelvic and inguinal nodal masses that were part of generalized disease from non-Hodgkin lymphoma.

Inguinal Abscess Axial CECT shows a loculated fluid collection that extended along the iliopsoas.

Groin Hematoma Axial NECT shows a heterogeneous, high-attenuation mass deep to the femoral vessels and superficial to the femur. This was found to be groin hematoma.

Iliopsoas Bursitis Sagittal CECT shows a cylindrical fluid collection along the right iliopsoas muscle near its insertion on the femur.

Inguinal Hernia Axial CECT shows an inguinal hernia containing only fat. Hernia is anterior to pubic tubercle, and there is no compression of femoral vessels .

Groin Pseudoaneurysm Sagittal color Doppler US shows a yin-yang or to-and-fro flow of blood within a spherical common femoral artery pseudoaneurysm, resulting from cardiac catheterization.

Groin Hematoma Axial CECT shows a groin hematoma that resulted from surgical revision of an AV fistula for dialysis. Unlike a pseudoaneurysm, there is no enhancement of the mass.

Femoral Hernia Coronal CECT shows a knuckle of small bowel that is incarcerated within a femoral hernia, resulting in small bowel obstruction.

Cryptorchidism Axial CECT shows a small soft tissue mass within the right inguinal ring. The right hemiscrotum was small and empty. Normal left spermatic cord is noted.

Femoral Hernia Axial CECT shows a left-sided femoral hernia , with the herniated bowel just medial to the femoral vessels.

Iliopsoas Bursitis Axial CECT shows a cylindrical fluid collection along the right iliopsoas muscle, near its insertion on the femur.

24 KiB Raw Blame History

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Helpful Clues for Common Diagnoses

Helpful Clues for Less Common Diagnoses

Helpful Clues for Rare Diagnoses