Case Report

Giant Iliopsoas Bursitis: SonographicFindings with Magnetic ResonanceCorrelations

Stefano Bianchi, MD,1 Carlo Martinoli, MD,2 Alain Keller, MD,1 Maria Pia Bianchi-Zamorani, MD3

1 Departement de Radiologie, Division de Radiodiagnostic et de Radiologie Interventionnelle, Hopital CantonalUniversitaire de Geneve, Rue Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland2 Cattedra di Radiologia “R,” DICMI-Universita di Genova, Largo Rosanna Benzi 8, I-16132 Genova, Italy3 Hopital Cantonal Universitaire de Geneve, Rue Micheli-du-Crest 24, CH-1211 Geneva 14, Switzerland

Received 12 November 2001; accepted 7 February 2002

ABSTRACT: We present the case of a 40-year-old man

with rheumatoid arthritis who had a painless left in-

guinal mass. Sonographic examination revealed a

large soft tissue mass with mixed internal echotexture

and regular borders extending inside the pelvis and

into the proximal portion of the thigh. Sonography

also showed communication between the bursa of the

iliopsoas muscle and the hip cavity, with intra-

articular synovitis and erosion of the ileum. Giant il-

iopsoas bursitis secondary to hip involvement in rheu-

matoid arthritis was diagnosed on the basis of the

sonographic findings. This diagnosis was confirmed

by MRI. © 2002 Wiley Periodicals, Inc. J Clin Ultra-

sound 30:437–441, 2002; Published online in Wiley

InterScience (www.interscience.wiley.com). DOI:

10.1002/jcu.10093

Keywords: ultrasonography; iliopsoas bursitis; rheu-

matoid arthritis; cyst; synovitis

The hallmark of iliopsoas bursitis (IB) is en-largement of the bursa of the iliopsoas muscle

(iliopsoas bursa) due to either synovial fluid orhypertrophic synovium. IB is usually associatedwith hip disease and presents as a mass in thegroin.1–5 Diagnosing IB clinically can be difficult,and imaging is usually required to differentiateIB from other groin masses such as lymphadenop-athy, hernias, and tumors. We report the case of apatient with rheumatoid arthritis (RA) who had agiant IB that was diagnosed on the basis of sono-graphic findings and confirmed by MRI.

CASE REPORT

A 40-year-old man visited the hospital for evalu-ation of a slow-growing, painless mass in the leftside of his groin. The patient had a history of se-ropositive nodular RA and type 2 diabetes melli-tus. Physical examination revealed joint deformi-ties in his hands and wrists; these deformitieswere typical of RA. Multiple rheumatoid noduleswere also found, mainly in the olecranal regions.The patient had limited range of motion in bothhips. Palpation of the left inguinal area revealed afusiform swelling. No skin changes or bruits weredetected over the mass. Vague discomfort oc-curred on deep palpation of the groin.

Sonography was performed to evaluate themass and to determine its extent and relationshipwith surrounding structures. Gray-scale andcolor Doppler sonography was performed with anSSD 5500 PureHD ultrasound scanner (Aloka,Tokyo, Japan) equipped with a 3.5-MHz curved-array transducer and a 7.5–10-MHz linear-arraytransducer operating at 10 MHz. Axial and sag-ittal sonograms were obtained over the anterioraspect of the left hip while the patient was in asupine position.

Sonography showed a large, complex, mostlysolid mass (19 × 8 × 5 cm) with smooth, regularborders. One component of the mass was extra-pelvic (Figure 1), located anterior to the hip cap-sule, medial to the psoas tendon, and immediatelylateral to the femoral vessels. Another componentwas intrapelvic, extending into the retroperitone-al space of the pelvis along the iliopsoas muscle.

Correspondence to: S. Bianchi

© 2002 Wiley Periodicals, Inc.

VOL. 30, NO. 7, SEPTEMBER 2002 437

On axial sonograms, this retroperitoneal portionwas shaped like a horseshoe and was located lat-eral to the iliac vessels, medial to the psoasmuscle, and inferior to the iliac muscle, lying be-tween the iliac muscle and the ilium (Figure 2).Sagittal sonograms showed both components ofthe mass and allowed measurement of its longest

diameter (19 cm; Figure 3). The internal mixedechotexture was caused by moderately echoicfronds, thought to represent hypertrophic syno-vium, that almost completely filled the mass andby scattered anechoic areas representing spacesfilled with synovial fluid. Internal signals wereminimal on color Doppler sonography, indicatinga hypovascular pannus. Communication betweenthe mass and the anterior hip joint space wasevident (Figure 4A). Intra-articular surface de-fects of the cortex of the femoral head, corre-sponding to erosions caused by hypertrophy of the

FIGURE 1. Axial images showing the extrapelvic component of the

distended bursa of the iliopsoas muscle. (A) Sonogram obtained at

the level of the left groin shows the iliopsoas bursitis as a well-

demarcated complex mass (calipers) with internal hypertrophied

synovium (long arrows) and anechoic spaces containing synovial

fluid (short arrows). The mass is located medial to the iliopsoas ten-

don (T). (B) T1-weighted MRI scan obtained at the same level as in the

sonogram after intravenous injection of gadolinium shows the ilio-

psoas bursitis (asterisk) as a mass located between the femoral ves-

sels (FV) and the iliopsoas tendon (T). Note the contrast enhancement

of the internal septa (arrows).

FIGURE 2. Axial images showing the intrapelvic component of the

iliopsoas bursitis. (A) Color Doppler sonogram of the lateral aspect of

the pelvis shows the iliopsoas bursitis (asterisk) as a horseshoe-

shaped mass that surrounds the echogenic iliopsoas tendon (T). The

lesion’s lateral portion (arrows) is located between the tendon and the

ilium (B). The iliac vessels (IV) are displaced medially. (B) T2-weighted

MRI scan, oriented to match the sonogram, shows corresponding

findings.

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438 JOURNAL OF CLINICAL ULTRASOUND

synovial membrane, and fluid and pannus insidethe joint space were also present and confirmedthe involvement of the joint in RA (Figure 4B).The iliac and femoral vessels were located at themedial aspect of the mass. Color Doppler sono-graphic examination confirmed the absence ofvenous thrombosis.

MRI evaluation was then performed using a1.5-T unit (Eclipse; Marconi, Cleveland, OH).Before and after intravenous administration ofgadolinium, axial T1-weighted, sagittal fat-suppressed T2-weighted, and coronal proton-density T2-weighted images were obtained usinga surface coil (Figures 1B, 2B, and 3B). MRI ex-amination showed an enlarged bursa of the ilio-psoas muscle filled with pannus and synovialfluid, with intrapelvic extension of the mass.These findings confirmed the diagnosis of a giantIB. Parietal and septal enhancement was evidentafter intravenous injection of the paramagneticcontrast agent. Correlation between the MRIscans and sonograms was excellent (Figures 1and 2). However, the intra-articular bone erosionscaused by the pannus were more easily detectedand appeared larger on MRI than on sonography.

DISCUSSION

Under normal conditions, the iliopsoas bursa, thelargest para-articular synovial bursa of the hipregion, is collapsed. This bursa, lined by syno-vium and located between the iliopsoas tendonand the anterior aspect of the hip joint, reducestendon friction over the hip joint during muscleactivation and joint movement.4 Communicationbetween the iliopsoas bursa and the hip joint isfound in 15% of individuals and can be congenitalor acquired.4 In cases of acquired communication,repeated friction and chronic synovitis can resultin tears in the synovial membrane and subse-quent passage of synovial fluid into the iliopsoasbursa, causing it to enlarge. Common disordersthat have been associated with IB include osteo-arthritis, RA, gout, osteonecrosis, and total hipreplacement. It is interesting that all these con-ditions are chronic, and all are associated with anincrease in intra-articular pressure due to exces-sive production of synovial fluid. The high intra-articular pressure facilitates communication be-tween the joint space and the iliopsoas bursa andmay explain the progressive extension of the

FIGURE 3. Sagittal images showing the entire iliopsoas bursitis. (A) Longitudinal sonogram shows both the intrapelvic and extrapelvic components

of the iliopsoas bursitis (arrows). I, Ilium. (B) Sagittal fat-suppressed T2-weighted MRI scan, oriented to match the sonogram, shows corresponding

findings. The asterisk indicates the iliopsoas bursitis.

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mass into the pelvis in our patient. The mecha-nism of enlargement of the iliopsoas bursa ap-pears to be analogous to that of Baker cysts inpatients with RA, which, because of communica-tion with the chronically inflamed knee, cangradually expand and progress within the calf toreach the ankle.

IB can either be asymptomatic or cause varioussymptoms related to compression of adjacentstructures. In the groin, pressure on the femoralvein can cause outflow impairment, limb edema,1

and, possibly, venous thrombosis, whereas exces-sive pressure on the femoral nerve can cause neu-ral impairment.2 Compression of various intra-pelvic structures has been also described.5,6

Various conditions, including hernias of the in-traperitoneal content, tumors, aneurysms of theiliac or common femoral vessels, and lymphade-nopathy, can cause a groin mass. These condi-tions can present with nonspecific clinical symp-toms, and imaging is usually required fordiagnostic evaluation. Sonography is the first-line

technique for assessing groin masses because ithas relatively low cost, is noninvasive and dy-namic, and allows mapping of blood flow. Real-time sonographic examination can show hernia-tion of the bowel and mesentery accompanied byvisible peristalsis. An aneurysm can be diagnosedon the basis of the relationship of the mass withthe vessels and high internal signals on colorDoppler sonography. Lymphadenopathy of theiliac chain appears on sonography as multipleuniformly hypoechoic solid masses. The sono-graphic findings of IB are a cystic mass composedof folds of hypertrophied synovium interspersedwith smaller cystic areas. Demonstration of com-munication between the mass and the joint spaceand correlation of sonographic findings with clini-cal data is critical in confirming the diagnosis ofIB secondary to RA of the hip. Sonography allowseasy and quick evaluation of the relationship ofthe mass with the adjacent structures and theinternal structure of the lesion. Moreover, if anaspiration biopsy specimen of the lesion must be

FIGURE 4. Axial sonograms showing the hip joint. (A) Sonogram obtained at the level of the hip joint reveals

the communication (arrow) between the iliopsoas bursitis (asterisk) and the joint space (JS). FH, femoral head.

(B) Sonogram obtained in a slightly more caudal and lateral position than in 4A shows the joint space (JS)

distended by the hypoechoic synovial pannus. The intra-articular surface defect (arrows) of the cortex of the

femoral head (FH) indicates an erosion caused by hypertrophy of the synovial membrane.

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440 JOURNAL OF CLINICAL ULTRASOUND

obtained, sonography can help in guiding theneedle and avoiding inadvertent vessel injury.Other imaging modalities such as CT or MRI canbe effective in the study of IB but are more ex-pensive and time consuming than sonography.However, MRI is needed to evaluate the hip joint,particularly if chronic synovitis or osteonecrosisof the femoral head is suspected.

In summary, sonographic examination of an in-guinal mass in a man with RA revealed a largemass, with intrapelvic extension, that was be-lieved to be a giant IB. MRI confirmed this diag-nosis. The possibility of IB must always be con-sidered in the sonographic evaluation of cysticmasses in the groin or pelvis. Knowledge of thisunusual entity, accurate imaging to show commu-nication between the mass and the hip joint, anddemonstration of an associated hip disease arekey to successfully diagnosing IB.

REFERENCES

1. Pellman E, Kumari S, Greenwald R. Rheumatoidiliopsoas bursitis presenting as unilateral legedema. J Rheumatol 1986;13:197.

2. Yoon TR, Song EK, Chung JY, et al. Femoral neu-ropathy caused by enlarged iliopsoas bursa associ-ated with osteonecrosis of femoral head—a case re-port. Acta Orthop Scand 2000;71:322.

3. Salmeron I, Cardenas JL, Ramirez-Escobas MA, et al.Idiopathic iliopsoas bursitis. Eur Radiol 1999;9:175.

4. Ginesty E, Dromer C, Galy-Fourcade D. Iliopsoasbursopathies. A review of twelve cases. Revue duRhumatisme English Edition 1998;65:181.

5. Janus C, Hermann G. Enlargement of the iliopsoasbursa: unusual cause of cystic mass on pelvic sono-gram. J Clin Ultrasound 1982;10:133.

6. Bagnolesi P, Cilotti A, Camerini E. Distension of themucous bursa of the iliopsoas muscle: a rare expan-sive process of the pelvic cavity. Radiol Med (Torino)1989;77:559.

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