sign in sign up
<<
Home , Canal of Nuck, Inguinal canal, Ovarian ligament

Radiologic Evaluation of Masses: From to Hydroceles

Dr. Andrew Fox McGill University Health Centre, Montreal, Quebec, Canada

Dr. Vincent Pelsser Jewish General Hospital, Montreal, Quebec, Canada

Objectives

• To provide an overview of hernias and how they can be differentiated on imaging.

• To provide a review of the differential diagnosis of inguinal pathology simulating groin hernias for which the radiologist should be aware.

Disclosures

• Nothing to disclose. Inguinal Anatomy Basics

• The is a diagonally oriented tunnel lined by the aponeuroses of the musculature.

• It begins at the internal/deep inguinal ring, a gap in the transversalis above the inguinal and posterolateral to the inferior epigastric vessels.

• It terminates at the superficial inguinal ring, an opening in the external oblique , superolateral to the .

• The canal serves as the passageway of the in males and the round ligament of the in females, in addition to lymphatics, sympathetic nerve fibres and connective tissue. Normal Inguinal Anatomy on CT C+

Inferior epigastric artery Spermatic cord (green) Spermatic cord (green) at (yellow) arises from within the inguinal canal. the level of the superficial external iliac artery (red). Adjacent inguinal inguinal ring. The femoral Fat encircles the ligament (blue) and vessels (red) are lateral spermatic cord (green) as external iliac artery (red). within the femoral canal, it transits the internal along with the node of inguinal ring. Cloquet (brown). DifferentialGroin Hernias Diagnosis of an Inguinal Mass

• By far, the most common type of abdominal is the , representing 80% of cases (1). • Hernias: Inguinal (direct, indirect), femoral, obturator.

• Congenital/Reproductive: Inguinal hernias are classified Cysts, as either , Direct or Indirect retractile based on testes, their endometriosis.relationship to the inferior epigastric vessels.

• Neoplasia: Primary vs metastatic. • Femoral hernias account for only 5% of abdominal hernias, however prompt • Vascular:clinical and Pseudoaneurysm/aneurysm, radiological diagnosis is necessary hematoma, as 40% , manifest with fistula. strangulation (1). • Infectious or Inflammatory. • Hernia contents range from intra-abdominal fat and bowel loops, to bladder and reproductive organs. Inguinal Hernias - Direct

• Direct inguinal hernias occur via a defect in the within the Hesselbach triangle.

 The Hesselbach triangle is bordered by the medially, the inferior epigastric vessels superolaterally, and the inferiorly.

• Therefore, direct inguinal hernias occur inferomedial to the inferior epigastric vessels.

• More common in men, with lowest incidence of strangulation amongst groin hernias (4).  Right direct inguinal hernia containing bowel and (Burkhardt, Arshanskiy, Munson, & Scholz, 2011) mesenteric fat. The hernia sac is medial to the inferior epigastric vessels (red arrow). A fat-containing left inguinal hernia is also present. Inguinal Hernias - Indirect

• Indirect inguinal hernias enter the deep/internal inguinal ring and extend through the inguinal canal.

• Therefore, they occur lateral to the inferior epigastric vessels and Hesselbach triangle.

• In men, the contents can extend through the superficial ring into the  , while in women, they can  82M presenting with scrotal follow the round ligament into the swelling. Static Grayscale and Doppler US images demonstrate majora (2). herniated bowel (orange arrows) within the left inguinal canal, • Indirect hernias are five times more entering into the scrotum. The common then direct hernias, with a hernia is lateral to the inferior epigastric vessels (yellow arrows), moderate risk of strangulation (1,2). shown above.

(Burkhardt, Arshanskiy, Munson, & Scholz, 2011) CT C+ from two patients with inguinal hernias. The image on the left shows an indirect hernia containing bowel. On the right, ascites is seen pooling within a direct hernia. Note the relative position of the inferior epigastric artery (red arrows). Femoral Hernias

• The femoral sheath is a fascial layer encircling the femoral artery and vein laterally, and femoral canal medially.  The is the widest part of the femoral canal.

• Femoral hernias extend through the femoral ring, below the inguinal ligament.

• They occur medial to the common femoral vein, often compressing it (2).

• Account for only 5% of abdominal hernias, however 40% manifest with strangulation (1).

• F:M ratio of 4:1, thought to be secondary to dilatation of the femoral ring due to the

hormonal and physical changes of pregnancy (Burkhardt, Arshanskiy, Munson, & Scholz, 2011) (5).

• The images on the right depict ascites within a right femoral hernia (white arrows).

• Note the position of the hernia inferolateral to the inguinal canal (green arrow) and anterior to the pectineus muscle (brown arrow).

• The hernia compresses the right common femoral vein, which appears slit-like relative to the contralateral side (blue arrows).

• For reasons unknown, femoral hernias are twice as common on the right (5).

Obturator Hernias

• Occur as a result of laxity in obturator canal, formed by the obturator fascia and membrane.

• The canal harbors the , vein and nerve, and traverses the obturator foramen.

• More common in elderly women and patients with chronically elevated intra-abdominal pressure, e.g. COPD (6).

• Female predominance may be due to more oblique course of the canal  and/or laxity of pelvic muscles 101F evaluated for DVT demonstrates a R obturator hernia containing fluid (green). Obturator hernias lie during pregnancy (6). deep to the pectineus (brown) and anterior to the obturator externus (yellow). Hernia complications

• Groin hernias can contain nearly any structure in the lower .  Most feared complications include bowel incarceration and obstruction, or strangulation.  Rarer cases include an incarcerated appendix (Amyand) or Meckels diverticulum (Littré).

CT C+ from a 57F with known  abdominal hernias. Axial slices demonstrate herniation of the Small bowel obstruction right (yellow arrow) within secondary to incarcerated an indirect inguinal hernia. The left obturator hernia utero- (blue (yellow). arrow) can be followed along the course of the hernia. A fat- containing inguinal hernia is  also present on the left. Strangulated bowel within an indirect left inguinal hernia (green). The bowel wall is edematous with adjacent fluid in the hernia sac. Congenital/Reproductive Differential Diagnosis of an Inguinal Mass • Embryologically, the testis and processus vaginalis are two key structures in normal gonadal development.  The gubernaculum (white open) is a fibrous ligament• Hernias: extending Inguinal from the (direct, gonads (blackindirect), closed) femoral, obturator. in the lower pelvis to the fetal groin, assisting in gonadal descent.  The• Congenital/Reproductive: processus vaginalis refers to a peritoneal Cysts, foldcryptorchidism, retractile testes, extendingendometriosis. through the inguinal canal and into the scrotum. It forms the testis in males and is obliterated in females. • Neoplasia: Primary vs metastatic. • The processus vaginalis is also referred to as the• Canal Vascular: of Nuck Pseudoaneurysm/aneurysm, in females. hematoma, varicocele, fistula.

• Failure• Infectious of obliteration or Inflammatory. of the processus vaginalis can lead to fluid accumulation within this potential space, referred to as a Canal of Nuck hydrocele.

• Failure of testis migration results in Cryptorchidism (image to the right). (Shadbolt, Heinze, Dietrich, 2011) Canal of Nuck Hydrocele

  Axial T1 (upper left), T2 (upper right) and T1 Fat-sat Post-Gadolinum (bottom left) MRI in a young female patient referred for evaluation of an inguinal mass. The study demonstrates a cystic, non-enhancing lesion in the right inguinal canal, which does not communicate with the (not shown). Findings are consistent with a Canal of Nuck hydrocele. Testis Migration

• Testis can be located at any point along path of embryologic descent, defined as either intraabdominal or cannilicular (outside ).

• They can also be ectopic in location, outside normal embryologic pathway (perineum, femoral canal...)

• Testicular retraction refers to transient proximal migration along the inguinal canal.

• Abnormal positioning of the testis results in increased risk of torsion and malignancy.  3M presenting with severe left inguinal pain with palpable mass. Doppler US shows a necrotic, avascular testis within the left inguinal canal. Some flow is seen in the epididymis.

 CT C+ from the same patient shows bilateral cannilicular location of the testes within the inguinal canals. The left testis (yellow) is enlarged and necrotic compared to the right (green). Inguinal Endometriosis

• Although endometriosis commonly affects the pelvis, inguinal disease is rare (8).

• They occur within the extraperitoneal portion of the round ligament, as well as well as along inguinal nodes and within hernias (8).

• Associated with malignant transformation to clear cell carcinoma (9), highlighting importance in prompt diagnosis.

 Grayscale US image from a young female patient with cyclical abdominal pain, demonstrates a 3.3x2.8cm lesion in the right ovary, with diffuse internal echoes.

 CT C+ from the same patient demonstrates an isodense, slightly ill-defined lesion (yellow arrow) in the left inguinal canal. Excisional biopsy confirmed endometriosis. Neoplasia Differential Diagnosis of an Inguinal Mass • Groin neoplasms are subdivided into  Axial CT C+ shows a fat benign and malignant pathologies. density lesion lateral to • Hernias: Inguinal (direct, indirect), femoral, obturator. the right spermatic cord • Tumors can arise from connective (blue arrow), compatible tissue (bone, tendon, cartilage), fat, with a lipoma. muscle,• Congenital/Reproductive: vasculature and lymphatics. Cysts, cryptorchidism, retractile testes, endometriosis. • The most common benign tumor of the• Neoplasia: inguinal canal Primary is a lipoma vs metastatic. of the spermatic cord (7). • Vascular:True lipomas Pseudoaneurysm/aneurysm, must have no connection hematoma, varicocele, fistula. to the retroperitoneal fat (10). • InfectiousOccur inferolateral or Inflammatory. to the cord vs fat- containing hernias which are anteromedial (3).  Axial CT C+ shows a • Additional benign tumors of the groin fat-containing L inguinal include neurofibromas of the hernia, anterior to the ilioinguinal or genitofemoral nerves spermatic cord (yellow (3) and desmoid tumors. arrow). Desmoid Tumor

• Rare tumors representing 3.5% of all fibrous tumors (11).

• Associated with Gardner syndrome, FAP, and surgical scars (12).

• When occurring in the groin region, they commonly manifest as a painful mass, +/- lower extremity edema (13).   Axial T1 (top left), T2 fat-sat • MR signal characteristics are low T1, (bottom left) and T1 fat-sat

heterogenous T2, and enhancement post-Gadolinium (top right) post-gadolium (14). MRI in a 37F presenting with right groin pain and palpable lump. Study demonstrates an enhancing mixed signal intensity lesion in the right Sartorius muscle. Biopsy results were compatible with desmoid tumor. Neoplasia - Malignant

• Malignant tumors commonly involve the inguinal region by direct extension, and can be either primary or metastatic (7).

• Primary neoplasms include sarcomas (liposarcoma, undifferentiated), Burkitt lymphoma and testicular/ embryonic cancer along the spermatic cord (3).

• Metastatic disease can either be from a pelvic primary (prostate, , penis, anorectal), lower extremities (melanoma), or systemic (lymphoma) (3,7), amongst others.



24M presenting with a left groin mass. Axial STIR (bottom) and T1 fat-sat post-Gadolinium (top) MRI

 shows a large heterogeneous, enhancing mass (green arrows) in the left pelvis extending through the femoral canal to the groin. Biopsy showed

undifferentiated sarcoma. Inguinal Lymphadenopathy

• The inguinal lymph nodes course along the greater saphenous vein and inguinal ligament.

• They drain the lower , external genetalia and lower third of vagina, anal canal, and lower extremities (15).

• Inguinal nodes can measure up to 2 cm in healthy individuals (16).

• More specific findings for adenopathy include loss of fatty hilum or evidence of necrosis.

• Etiologies include reactive nodes from local inflammation or infection, and malignancy (primary or metastatic).

 CT C- from a 61M with a palpable mass in the right groin. There are numerous enlarged right inguinal nodes (blue arrow). Final diagnosis was B-cell lymphoma.

 CT C- from a 46F with a history of melanoma. There is a large left inguinal lymph node (yellow arrow), confirmed to be metastatic melanoma. Vascular Etiologies • Most common vascular pathologies in theDifferential inguinal region are iatrogenic, Diagnosis of an Inguinal Mass sequelae of femoral artery manipulation.  Complications include hematomas and arterial• Hernias: pseudoaneurysm. Inguinal (direct, indirect), femoral, obturator. • True aneurysms are relatively rare, occuring• Congenital/Reproductive: in atherosclerotic vessels (7). Cysts, cryptorchidism, retractile testes, endometriosis. 

• Other vascular pathologies include 54F presenting with a palpable  ,• Neoplasia: and post-traumatic Primary vs AVmetastatic. groin mass post-femoral artery fistulas (7). catheterization. CTA images show a • Vascular: Pseudoaneurysm/aneurysm,saccular outpouching hematoma, with varicocele,a flap at fistula. the L CFA (red), compatible with pseudoaneurysm. • Infectious or Inflammatory.

 Doppler US in a different patient showing the characteristic yin- yang appearance, in a partially thrombosed pseudoaneurysm. Inguinal Hematoma

• 37M with recent vasectomy, presented with RLQ and right groin pain. CT was requested to r/o appendicitis.

CT C- demonstrates a hyperdense collection (HU 35) within the right inguinal canal, tracking along the spermatic cord into  the scrotum.  

 Doppler and Grayscale US confirm the presence of a largely hyperechoic collection tracking along the inguinal canal and scrotum. Findings are compatible with a post- operative hematoma. Infectious/Inflammatory

• GroinDifferential abscesses may either occurDiagnosis locally of an Inguinal Mass (sebaceous or sweat glands) or extend from distal sources, such as the retroperitoneum.

• As the hip joint forms the floor of the groin, • Hernias: Inguinal (direct, indirect), femoral, obturator. an inflammatory hip process can simulate a groin• massCongenital/Reproductive: (7). Cysts, cryptorchidism, retractile testes,  Examplesendometriosis. include bursitis, synovial osteochondromatosis and metal-on-metal   pseudotumor. CT C- fromCT the C- samein a 66Mpatient presenting demonstrating • Neoplasia: Primary vs metastatic. a large, withheterogenously fever, leukocytosis, calcified mass within inand the flank left pain.iliacus An muscleiliopsoas (yellow • Vascular: Pseudoaneurysm/aneurysm,arrows). hematoma, Exaggeratedabscess (yellow bone varicocele, windowarrow) (bottom)is fistula. shows tinyseen metallic extending particles along (green the arrow) • Infectious or Inflammatory. adjacent entireto the course prosthesis, of the muscle,resulting in pseudotumordown formation to the from tendinous metallosis.  insertion at the lesser trochanter.  Frontal radiograph from a patient with chronic hip pain post left THA.  CT C- from a patient with rightThere hip is dysplasia, dislocation presenting of the withprosthesis groin pain.(blue Therearrow), is fluidwith a expansionpartially calcified of the iliopsoas mass projectingbursa (brownover the arrow), left iliac suggestive fossa (yellow of arrow). Courtesy of Dr. F. Discepola. bursitis. Conclusion

• The groin is complex in pathology, ranging from hernias to malignancy.

• Knowledge of the anatomy and of the inguinal region is essential in characterizing lesions and providing an appropriate differential diagnosis.

• Collaboration between radiologists and clinicians is essential as the clinical course, in conjunction with the imaging findings, narrows the differential diagnosis and ultimately, improves patient care. References

1. Bailey H, Love RJM, Russell RCG, Williams NS, Bulstrode CJK. Bailey and Loves short practice of surgery. London, England: Arnold, 2000.

2. Burkhardt, J. H., Arshanskiy, Y., Munson, J. L., & Scholz, F. J. (2011). Diagnosis of inguinal region hernias with axial CT: the lateral crescent sign and other key findings. Radiographics : a Review Publication of the Radiological Society of North America, Inc, 31(2), E1–12. doi:10.1148/rg.312105129

3. Bhosale, P. R., Patnana, M., Viswanathan, C., & Szklaruk, J. (2008). The inguinal canal: anatomy and imaging features of common and uncommon masses. Radiographics : a Review Publication of the Radiological Society of North America, Inc, 28(3), 819–35– quiz 913. doi:10.1148/rg.283075110

4. Wechsler RJ, Kurtz AB, Needleman L, et al. Cross- sectional imaging of abdominal wall hernias. AJR Am J Roentgenol 1989;153(3):517–521.

5. Zarvan NP, Lee FT Jr,Yandow DR, Unger JS. Abdominal hernias: CT findings. AJR Am J Roentgenol 1995;164(6):1391–1395.

6. Glicklich M, Eliasoph J. Incarcerated obturator hernia: case diagnosed at barium enema fluoroscopy. Radiology. 1989;172 (1): 51-2.

7. Shadbolt, C., Heinze, S., & Dietrich, R. (n.d.). Imaging of Groin Masses: Inguinal Anatomy and Pathologic Conditions Revisited1. Radiographics, S261-S271.

8. S. Jenkins, D. L. Olive, and A. F. Haney, Endometriosis: pathogenetic implications of the anatomic distribution, Obstetrics and Gynecology, vol. 67, no. 3, pp. 335–338, 1986.

9. G. H. Ahn and R. E. Scully, Clear cell carcinoma of the inguinal region arising from endometriosis, Cancer, vol. 67, no. 1, pp. 116–120, 1991.

10. Lilly MC, Arregui ME. Lipomas of the cord and round ligament. Ann Surg 2002;235:586–590.

11. Hayry P, Reitamo JJ, Totterman S, Hopfner- Hallikainen D, Sivula A. The desmoid tumor. II. Analysis of factors possibly contributing to the etiology and growth behavior. Am J Clin Pathol 1982; 77:674–680.

12. Chevrel JP, Azorin J, Giraud JP, Rath AM. Total reconstruction of the femoral canal and the inguinal wall after resection of a recurrent desmoid tumor. Hernia 1999;3:153– 158.

13. Bhama P, Chugh R, Baker L, Doherty G. Gardners syndrome in a 40-year-old woman: successful treatment of locally aggressive desmoid tumors with cytotoxic chemotherapy. World J Surg Oncol 2006;4:96.

14. Martin DR, Semelka RC, Elias J, Kelekis NL. Retroperitoneum. In: Semelka RC, Abdominal-pelvic MRI. 2nd ed. Hoboken, NJ: Wiley, 2006; 1127.

15. Habermann TM, Steensma DP. Lymphadenopathy. Mayo Clin Proc. 2000;75:723-732.

16. Kozuch P, Grossbard ML. Lymphadenopathy. In: Clinical Hematology and Oncology. New York, NY: Churchill Livingstone; 2003;213-220.