Soft Tissue Pseudotumors of the Pelvis and Hip MAJ Weston T

This issue of CDR will qualify for 2 ABR Self-Assessment Module SAM (SA-CME) credits. See page 8 for more information.

Volume 40 • Number 7 March 31, 2017

Soft Tissue Pseudotumors of the Pelvis and Hip MAJ Weston T. Winkler, DO, Dillon C. Chen, MD, and COL (Ret) Liem T. Bui-Mansﬁ eld, MD

The opinions and assertions contained herein are those of the authors and should not be construed as offi cial or as representing the opinions of the Department of the Army, Department of the Air Force, or the Department of Defense. This module meets the American Board of Radiology’s (ABR’s) criteria for self-assessment toward the purpose of fulfi lling requirements in the ABR Maintenance of Certifi cation (MOC) program. Please note that in addition to the SA-CME credits, subscribers completing the activity will receive the usual ACCME credits. After participating in this educational activity, the radiologist should be better able to diagnose the common soft tissue pseudotumors of the pelvis and hip on different imaging modalities.

1 Category: General Radiology number of radiographic procedures that year. With its com- Subcategory: Musculoskeletal plex osseous and soft tissue anatomy, the pelvis provides a Modality: Multiple challenge for the radiologist to accurately evaluate, especially in the setting of unexpected fi ndings, such as “tumors.” In North America and Europe, the annual incidence of soft Key Words: Soft Tissue Pseudotumor, Myositis Ossifi cans, tissue sarcomas is approximately 30 cases per million Crystal Deposition Disease, Morel-Lavallee Lesion, people.2 In comparison, the prevalence of benign pseudotu- Tumoral Calcinosis, Pseudoaneurysm mors is signifi cantly higher. For example, acetabular para- Pelvic pseudotumors are a frequent fi nding discovered on labral cysts are seen on MRI in 13% to 26% of asymptomatic routine and emergent imaging examinations that often can patients.3 Femoral arteriovenous fi stulas after femoral access provide a diagnostic conundrum for general radiologists. occur in 1% of patients undergoing cardiac catheterization.4 This article provides imaging characteristics of various soft In 6,061 unselected asymptomatic persons subjected to fl uor- tissue pelvic and hip pseudotumors through a case-based oscopic examination of both shoulders, 165 (2.7%) were review. found to have calcium deposits in one or both shoulders.5 Because of these dramatic differences in frequency, the radi- In 2006, 20 million pelvis and hip radiographs were per- ologist is much more likely to encounter the pelvic tumor-like formed in the United States, comprising 7.2% of the total disease (pseudotumor) than a true tumor in his or her daily practice. Dr. Winkler is Radiology Resident, Dr. Chen is Assistant Professor, and Dr. Bui-Mansfi eld is Adjunct Professor, Department of Radiology, Uniformed Soft Tissue Pelvic Pseudotumors Services University of the Health Sciences, Bethesda, Maryland, and Musculoskeletal Radiology Section, Department of Radiology, Brooke Army The tumor mimickers include both intra- and extra-articular Medical Center, 3851 Roger Brooke Dr, Fort Sam Houston, TX 78234; E-mail: soft tissue masses, some of which radiologists will likely liem.mansfi [email protected]. encounter on a daily basis. A complete discussion of all soft The authors and all staff in a position to control the content of this CME activity tissue pseudotumors is beyond the scope of this article. For and their spouses/life partners (if any) have disclosed that they have no relation- ships with, or fi nancial interests in, any commercial organizations pertaining to the purpose of illustration, we limit our review to the follow- this educational activity. ing entities: bursitis, paralabral cysts, myositis ossifi cans,

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CCDRv40n7.inddDRv40n7.indd 1 222/02/172/02/17 2:252:25 AMAM crystal deposition disease, vascular lesions, Morel-Lavallee lesions, tendon rupture, radiation myositis, and tumoral calcinosis.

Bursitis Several normal bursae occur in the pelvis, including iliopsoas, obturator externus, trochanteric, and ischial tuber- osity. When infl amed or enlarged, these bursae can mimic pathology other than bursitis. Distention of the bursa usually is caused by overproduction of synovial fl uid in the arthritic hip, which leads to increased intra-articular pressure and A extension of the fl uid into the potential space of the bursa. Given the increasing use of cross-sectional imaging, the prevalence of incidental radiologic discovery of bursal enlargement also has increased (Figure 1). Of note, enlarged bursae also can be an indicator of underlying pathology such as septic arthritis, failure of hip arthroplasty, synovial neoplasm, and arthritides such as rheumatoid arthritis, and should, therefore, be investigated fully.

Paralabral Cyst Paralabral cysts are very common and have been described in patients with developmental dysplasia of the hip, femoro- acetabular impingement, osteoarthritis of the hip, and remote trauma. These cysts often are associated with labral tears. B Labral tears result in a loss of congruity between the femoral Figure 1. A 93-year-old woman presented with right hip pain. head and acetabulum causing increased intra-articular pres- Initial radiographs (not shown) revealed bilateral total hip arthro- sure and subsequent cyst formation. A paralabral cyst can be plasties with evidence of right-sided polyethylene wear and mistaken for soft tissue sarcoma. However, unlike sarcomas, medial displacement of the right obturator internus fat plane. A: paralabral cysts should demonstrate characteristically thin Review of a prior CT scan of the pelvis reveals a slightly hyper- walls, without signiﬁ cant thick septal or nodular internal dense, teardrop-shaped, cystic mass (arrow) coursing along the right iliopsoas muscle and arising near the arthroplasty. B: enhancement. The presence of a paralabral cyst on imaging Corresponding, previously obtained lumbar spine MR examina- should prompt a thorough search for underlying pathology. tion of the same patient helped to conﬁ rm the diagnosis of right Paralabral cysts are often asymptomatic; occasionally, how- iliopsoas bursitis secondary to polyethylene wear. A well-circum- ever, they may cause symptoms related to adjacent nerve scribed, cystic mass with internal debris and a low T2 signal impingement, such as sciatica. peripheral rim (arrow) lies just superior to the metallic implant.

Myositis Ossifi cans amorphous calcifi cation matures into dense bone. During the Myositis ossifi cans is a benign, solitary, self-limiting ossi- maturation process, the imaging appearance can appear rather fying mass typically occurring within skeletal muscle. It concerning, especially on MRI. The key to correct diagnosis generally is seen in younger patients as the sequela of prior is to follow the maturation of the calcifi cation temporally on trauma. The initial imaging appearance of myositis ossifi cans radiographs (Figure 2). Over the course of the maturation is soft tissue swelling with or without periostitis. About 1 process, the lesion should develop dense bony cortex at the month after the traumatic insult, sometimes sooner, amor- periphery of the lesion with a more radiolucent central area. phous, hazy, soft tissue calcifi cations develop. Over time, the In contradistinction, neoplasms such as extraskeletal

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CCDRv40n7.inddDRv40n7.indd 2 222/02/172/02/17 2:252:25 AMAM A

A B

Figure 3. A 60-year-old man with atraumatic right upper thigh pain. Initial radiographs (not shown) revealed a 1-cm lytic lesion in the subtrochanteric region of the right femur with a narrow zone of transition. MR examination revealed a low-signal lesion on a sagittal, T1-weighted image (not shown). A: This sagittal, T2-weighted, fat-saturated, MR image reveals a lesion measuring 4 × 8 mm at the linea aspera and high T2 signal within the hamstring musculature (arrow). B: Subsequent review of an axial CT scan of the pelvis, performed 2 months earlier, revealed disruption of the gluteus maximus tendinous insertion and adjacent calciﬁ c deposit (arrow) corresponding to the lytic lesion seen on hip radiograph (not shown). B The diagnosis is rupture of hydroxyapatite deposition.

Figure 2. A 53-year-old man presented to the orthopedic clinic mistaken by radiologists for other conditions.5 The imaging with right thigh pain. MR short T1 inversion recovery image (not shown) showed a heterogeneous mass within the vastus inter- fi ndings of CPPD and gouty arthritis can be quite dramatic, medius muscle. A: Axial, T1-weighted, fat-saturated, postcontrast given the amount of joint destruction, which may be mistaken MR image shows irregular peripheral rim enhancement (arrow). for something more sinister. Without any additional history, MR fi ndings are indeterminate. After the shoulder, the hip is the second most common joint B: After discussion with an orthopedic oncologist, a history of affected in HADD.6 Common locations include sites of ten- trauma to the right thigh was elicited, and a diagnosis of myositis ossifi cans was established. Repeat radiographs 4 months later don attachment such as the greater and lesser trochanters and revealed calcifi cation within the muscle of the anterior thigh consistent with hematoma evolution (arrow).

osteosarcomas or chondrosarcomas do not undergo this maturation process and will have their densest calcifi cation in the central aspect of the mass rather than in the periphery. The CT appearance of myositis ossifi cans mirrors that of radiographic fi ndings. The MR appearance of myositis ossifi cans can be exceed- ingly variable depending on the phase of maturation. The more immature lesions can appear extremely nonspecifi c and worrisome on MRI, mimicking soft tissue sarcoma, with heterogeneous T2 hyperintensity and extensive perilesional edema. Mature lesions are less problematic diagnostically, as they typically demonstrate internal fat on all MR sequences and a peripheral rim of low T1 and T2 signal intensity corresponding to the rim calcifi cation.6 Figure 4. An 88-year-old woman with right anterior thigh swelling. Crystal Deposition Disease Arterial phase, axial, contrast-enhanced CT scan shows a lobu- lated mixed density mass (thick arrow) adjacent to the common Crystal deposition disease, including hydroxyapatite dep- femoral artery (thin arrow). Internal calcifi cations and regions of osition disease (HADD), calcium pyrophosphate deposition intermediate density within the mass are consistent with a throm- disease (CPPD), and gout, is a common disorder that can be bosed pseudoaneurysm arising from the common femoral artery. 3

CCDRv40n7.inddDRv40n7.indd 3 222/02/172/02/17 2:252:25 AMAM Figure 6. A 29-year-old man with anterior thigh pain. Sagittal, T1-weighted MR image through the upper thigh shows a poorly deﬁ ned, feathery atrophy within the rectus femoris muscle (arrow), with chronic tearing of the myotendinous junction.

CPPD and gout are less common than HADD around the hip. Calcium pyrophosphate tends to deposit in the hyaline cartilage and fibrocartilage, which can lead to joint destruction, productive arthropathy, and joint space widening. In the pelvis, pseudogout is seen most commonly in the sym- physis pubis, followed by the hip joint. The common imaging features of gout include periarticular dense tophi and juxta- articular erosions. The key to diagnosis is recognition of the calciﬁ cation pattern of CPPD and gout on radiographs. If the diagnosis remains problematic and correct diagnosis is needed to determine proper therapy, dual-energy CT can be helpful to avoid aspiration of the calciﬁ ed deposits for crystal analysis. Because of the differences in the atomic number of calcium and urate crystals, dual-energy CT can distinguish HADD or CPPD from gouty tophus. On dual- energy CT, HADD or CPPD appears blue, whereas gouty tophus appears green.

Vascular Lesions Several vascular lesions can occur around the pelvis and mimic tumors. These vascular lesions include venous malformations, arteriovenous malformations (AVMs), arteriovenous fistulas, and pseudoaneurysms. In general, B appropriate clinical history can be extremely helpful for cor- Figure 5. A 62-year-old woman fell off a ladder. A left hip radio- rect diagnosis. Venous malformations, previously known as graph (not shown) revealed prominent soft tissue swelling adjacent soft tissue hemangiomas, are slow-fl ow lesions that often to the greater trochanter. A: Coronal, T1-weighted MR image shows contain internal phleboliths. On ultrasound, venous malfor- a heterogeneous cystic lesion (arrow) with high and low signal mations demonstrate internal slow-moving debris with no representing fat or lymphatic material. B: Coronal, T2-weighted, fat-suppressed MR image clearly shows internal fat globules char- arterial fl ow. Often, the mass is pliable and compressible. acteristic of Morel-Lavallee lesions (arrow). Also note the presence AVMs are high-fl ow lesions, often tangled without an asso- of a pseudocapsule, which is well delineated on this MR image. ciated soft tissue mass. AVMs and venous malformations can have bone involvement, resembling a destructive mass. the linea aspera. Although frequently asymptomatic, HADD MRI often is diagnostic, demonstrating the tangle of abnor- can result in extensive soft tissue infl ammation and pain mal vessels with fl ow voids in the AVM. Venous malforma- when the calcifi c deposits are ruptured into the adjacent mus- tions usually have fat signal intensity within the lesion on cle, bursa, or bone. Calcium hydroxyapatite deposits appear MRI because of fatty atrophy of the affected muscle. homogeneous and amorphous on radiographs.7 In some Arteriovenous fi stulas usually are the sequela of peripheral cases, HADD can cause adjacent bone erosion, mimicking vascular access, which transgresses both the arterial and an aggressive process such as neoplasm (Figure 3). The key venous systems. On Doppler ultrasound, turbulent, high-fl ow to the correct diagnosis is to recognize the presence of HADD shunting is demonstrated. On IV contrast examinations, there calcifi cation on radiography or CT and to identify the tendon is pathognomonic simultaneous venous and arterial fi lling. attachment as the epicenter of the pathology. Pseudoaneurysms are vascular outpouching defects involving

CCDRv40n7.inddDRv40n7.indd 4 222/02/172/02/17 2:252:25 AMAM Morel-Lavallee Lesion The Morel-Lavallee lesion represents a posttraumatic closed degloving injury associated with severe trauma. It was fi rst described by the French physician Maurice Morel- Lavallee in the 19th century. The lesion represents a collec- tion of blood products, fat, and lymphatic material between the fascial layers of the greater trochanter, buttock, and back, and it can be mistaken for neoplasm. Sonographic appearance is variable, ranging from anechoic to hyperechoic mass. CT may show a fl uid–fl uid level within an encapsu- lated mass. MRI can be pathognomonic by demonstrating fat globules within a cystic mass, with a peripherally low T1 and T2 signal intensity rim (hemosiderin lined) (Figure 5).8 Treatment options include compression bandage, sclerosing therapy, and incision and drainage. Aspiration of more than A 50 mL of fl uid from Morel-Lavallee lesions is highly predictive of recurrence and should prompt operative intervention.

Tendon Rupture The pelvis is home to a complex network of muscles and tendons. These tendons can be classiﬁ ed into four quadrants on the basis of anatomic location and function: anterior—hip

Figure 8. A 62-year-old woman with a history of radiation therapy to the right hemipelvis. CT of the pelvis showed unchanged ero- sive bony lesion within the inferior right iliac bone (not shown). B This axial, T2-weighted MR image of the pelvis reveals non– mass-like edema throughout the right gluteal, iliac, and lower Figure 7. A 90-year-old woman with incidental ﬁ nding of a mixed pelvic musculature in a linear distribution (arrow). fatty and soft tissue mass within the anterior compartment of the left thigh, extending from the inferior margin of the rectus femoris muscle (not shown). A: Follow-up CT scan demonstrates fatty replacement within the atrophied rectus femoris muscle (arrow). B: Coronal, reformatted CT scan through the upper thigh shows the feathery pattern of fatty atrophy within the rectus femoris muscle (arrow) without internal soft tissue mass.

fewer than the three layers of the normal artery. Femoral pseudoaneurysms are due most commonly to cardiac catheterization, with prevalence up to 8%. On ultrasound, the “Yin-Yang” sign on color Doppler with a “to and fro” pattern on pulsed Doppler is characteristic. Anatomically, a neck connecting the contained hematoma to the injured vessel sometimes can be seen on CT (Figure 4). Most femoral pseudoaneurysms require only watchful waiting; however, those with a volume greater than 6 cm3 will require intervention, Figure 9. A 26-year-old woman presented with right hip swelling. This AP radiograph of the pelvis demonstrates bilateral amor- because spontaneous thrombosis is unlikely. Treatment phous soft tissue calciﬁ cations overlying the right and left greater options include ultrasound-guided compression directly over trochanters, measuring up to 9 cm (arrow) and 3 cm, respectively. the pseudoaneurysm, embolization, and covered stenting. This is consistent with uremia-related tumoral calcinosis.

CCDRv40n7.inddDRv40n7.indd 5 222/02/172/02/17 2:252:25 AMAM Table 1. Summary of Clinical and Imaging Features of Soft Tissue Pseudotumors of the Pelvis and Hip Entity History Location Imaging Findings Bursitis Nonspecifi c. May be Typical bursal locations Thin-walled cyst asymptomatic Iliopsoas No enhancement on MRI Obturator externus Trochanteric Ischial Paralabral cyst Nonspecifi c. May be Usually near labrum Thin-walled cyst asymptomatic Should raise suspicion for underlying labral pathology Myositis Prior trauma Skeletal muscle Varies depending upon stage of radiologic progression ossifi cans Early: Soft tissue swelling 1 mo: Flocculated calcifi cations Later: Mature, dense bony cortex at periphery of lesion with central lucency Crystal Pain. Sometimes with Most commonly HADD: Homogeneous calcifi c densities, usually at sites deposition known systemic periarticular or at of tendons insertion disease disease tendinous insertions CPPD: Lines hyaline and fi brocartilage, potentially leading to joint destruction Gout: Periarticular tophi AVF Almost always associated Anterior compartment Turbulent high-fl ow shunting of blood on Doppler with penetrating trauma upper thigh examination or percutaneous Simultaneous venous and arterial fi lling on contrast- catheterization enhanced CT Pseudoaneurysm Usually associated with Anterior compartment “Yin-Yang” sign on color Doppler prior percutaneous upper thigh “To and fro’” pattern on pulsed Doppler catheterization May see neck connecting to vasculature Vascular Usually incidental Can occur anywhere Slower fl ow than AVFs malformation Transfascial Central vascular nidus Morel-Lavallee Trauma Greater trochanter Well defi ned lesion Buttock Internal fat globules Lower back Capsule with low T1 and T2 signal intensity Tendon rupture/ Related to prior sports Extensor compartment Common locations tear injury or trauma. Gluteal insertions Does not cross tissue planes However, may be found Hamstrings Direct evidence of tendon tear incidentally, especially Muscle retraction in the setting of muscle atrophy No discrete mass No enhancement Radiation Prior radiation Confi ned to the Preservation of normal feathery pattern of muscle signal myositis radiation fi eld intensity with fusiform shape Sharp margins of edema that cross fascial plane Tumoral Usually incidental. Extensor surfaces in a Fluid–fl uid levels from calcium sedimentation calcinosis Commonly forms in the bursal distribution MRI is variable fi rst two decades of life AVF, arteriovenous fi stula; CPPD, calcium pyrophosphate deposition disease; HADD, hydroxyapatite deposition disease.

fl exors; lateral—abductors and medial rotators; medial— Radiation Myositis adductors; and posterior—extensors and external rotators. Female gynecologic cancers (10%–15% of cancers in Overall, tendon tears are uncommon and generally are seen women)9 represent the most common cause for radiation to in elderly women, suggesting a hormonal infl uence. These the pelvis. Radiation therapy causes vasculitis and tissue tendon injuries may mimic other etiologies of hip pain. Acute injury, which can be seen on MR images as uniform muscle complete tears may present clinically and on imaging as an edema throughout the radiation fi eld, with characteristic anterior thigh mass (Figure 6). Chronic tendon tear may straight, sharp margins that extend uninterrupted across mimic a lipomatous neoplasm because of atrophy and fat muscle and subcutaneous fat planes (Figure 8). Other MRI infi ltration of the involved muscle (Figure 7). clues include persistence of the normal feathery pattern of

CCDRv40n7.inddDRv40n7.indd 6 222/02/172/02/17 2:252:25 AMAM muscle signal intensity, with a normal fusiform shape to the patient anxiety, and exorbitant medical costs. As discussed muscle. Postcontrast, there is no abnormal enhancement. In in this review, pseudotumors of the hip and pelvis are sig- addition, evaluation of the myotendinous junction can be nifi cantly more common than primary neoplasms, benign or helpful because tendons typically are displaced by tumors malignant, of the soft tissue. Therefore, when presented with but may remain in normal position with an infl amed muscle. a soft tissue mass in the pelvis and hip on cross-sectional examinations, the interpreting radiologist must consider a Tumoral Calcinosis pseudotumor in the differential diagnosis. By including his- Tumoral calcinosis is caused by hereditary metabolic tory, prior imaging, laboratory evaluation, and additional dysfunction of phosphate regulation associated with imaging, the radiologist can play a critical role in reaching massive periarticular calcinosis. These lesions typically the correct diagnosis of a pelvis soft tissue mass (see Table 1). proliferate in the fi rst 2 decades of life and have characteristic radiographic appearance of amorphous, cystic, and References multilobulated calcifi cations (Figure 9). The lesions typi- 1. Mettler FA, Bhargavan M, Faulkner K, et al. Radiologic and nuclear medicine cally are located in a bursal distribution. Thus, hip and studies in the United States and worldwide: frequency, radiation dose, and shoulder are the two most common sites. The lesions also comparison with other radiation sources—1950-2007. Radiology. 10 2009;253:520-531. have a predilection for extensor surfaces. On CT, the 2. Fletcher CDM, Unni KK, Mertens F, eds. World Health Organization lesions often demonstrate fluid–fluid levels caused by Classifi cation of Tumours. Pathology and Genetics of Tumours of Soft Tissue calcium layering, commonly referred to as the “sedimenta- and Bone. Lyon, France: IARC Press; 2002. 3. Silvis ML, Mosher TJ, Smetana BS, et al. High prevalence of pelvic and hip tion sign.” Unlike HADD, tumoral calcinosis does not magnetic resonance imaging fi ndings in asymptomatic collegiate and profes- cause bone erosion or osseous destruction. There may be sional hockey players. Am J Sports Med. 2011;39:715-721. communication with nearby bursa.10 MR appearance of 4. Gonzalez SB, Vilanova Busquets JC, Figueiras RG, et al. Imaging arteriovenous fi stulas. AJR Am J Roentgenol. 2009;193:1425-1433. tumoral calcinosis is variable with both high and low T2 5. Bosworth BM. Calcium deposits in the shoulder and subacromial bursitis: a signal patterns described. Therefore, radiography, appropri- survey of 12,222 shoulders. JAMA. 1941;116:2477-2482. ate clinical history, and laboratory workup are key to mak- 6. Kransdorf MJ, Meis JM, Jelinek JS. Myositis ossifi cans: MR appearance with radiologic-pathologic correlation. AJR Am J Roentgenol. 1991;157: ing the correct diagnosis. 1243-1248. 7. Flemming DJ, Murphey MD, Shekitka KM, et al. Osseous involvement in Conclusion calcifi c tendinitis: a retrospective review of 50 cases. AJR Am J Roentgenol. 2003;181:965-972. This CME activity emphasizes that the pelvis with its com- 8. Gilbert BC, Bui-Mansfi eld LT, Schuyler D. MRI of a Morel-Lavallee lesion. plex anatomy and many neoplastic and nonneoplastic pro- AJR Am J Roentgenol. 2004;182:1347-1348. cesses can present a daunting challenge for even the 9. Kehoe S. Treatment for gynaecological cancers. Best Pract Res Clin Obstet Gynaecol. 2006;20:985-1000. experienced radiologist. Unnecessary diagnostic workup for 10. Olsen KM, Chew FS. Tumoral calcinosis: pearls, polemics, and alternative benign lesions can lead to potential patient harm, increased possibilities. Radiographics. 2006;26:871-885.

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CCDRv40n7.inddDRv40n7.indd 7 222/02/172/02/17 2:252:25 AMAM 1. Which one of the following is highly predictive of recur- 5. All of the following are MRI features that favor radiation rence of a Morel-Lavallee lesion about the pelvis and hip? myositis about the pelvis and hip, except A. Presence of a fluid-fluid level on CT A. sharp margins of muscle edema B. Absence of fat globules within a cystic mass B. normal feathery pattern of high T2 signal intensity C. Aspiration of more than 50 mL of fluid from the lesion within muscles D. High T2 signal intensity rim about cystic mass C. normal fusiform shape of muscles See Reference No. 8 for further study D. edema crossing muscle and fat planes without 2. All of the following are potential causes of bursitis around disruption the pelvis and hip, except E. tendon displacement A. failure of hip arthroplasty See Reference No. 9 for further study B. rheumatoid arthritis 6. Phleboliths about the pelvis and hip most commonly occur in C. septic arthritis A. pseudoaneurysm D. synovial neoplasm B. arteriovenous fistula E. labral tear C. arteriovenous malformation See Reference No. 2 for further study D. venous malformation 3. Which one of the following statements concerning HADD See Reference No. 4 for further study and CPPD deposits about the pelvis and hip is false? 7. Which one of the following is the most specific imaging A. CPPD is more common than HADD around the hip. feature of myositis ossifications about the pelvis and hip? B. The hip is the second most common joint affected in HADD. A. Presence of periostitis on radiographs C. A common location of HADD is tendinous attachment B. Heterogeneous hyperintensity on T2 MR images on the hip trochanters. C. Dense bony cortex at the periphery of the lesion on D. CPPD tends to deposit in hyaline cartilage and radiographs over time fibrocartilage. D. Extensive perilesional edema on MR images E. HADD can cause adjacent bone erosion. See Reference No. 6 for further study See Reference No. 7 for further study 8. Which one of the following statements regarding femoral 4. Figure 10 is a Doppler ultrasound of a 58-year-old man pseudoaneurysms about the pelvis and hip is false? who developed a left groin mass after femoral artery cath- A. They are due most commonly to cardiac catheterization. eterization. What should be the next step in this patient’s B. They contain all three layers of the normal artery. management? C. Watchful waiting is the usual treatment for small A. Consult an interventional radiologist lesions. B. Contrast-enhanced CT examination D. “To and fro” pattern on pulsed Doppler is C. Contrast-enhanced MR examination characteristic. D. Fluorodeoxyglucose positron emission tomography E. Those with a volume greater than 6 cm3 require imaging treatment. E. Repeat Doppler ultrasound in 3 months See Reference No. 4 for further study See Reference No. 4 for further study 9. In which anatomic structure does tumoral calcinosis typically deposit about the pelvis and hip? A. Bursa B. Fascia C. Muscle D. Skin E. Tendon See Reference No. 10 for further study 10. The incidence of acetabular paralabral cysts seen on MRI in asymptomatic patients is A. 2% B. 13% C. 32% D. 45% E. 65% Figure 10. See Reference No. 3 for further study

CCDRv40n7.inddDRv40n7.indd 8 222/02/172/02/17 2:252:25 AMAM