Iliopsoas compartment: normal anatomy and pathologic processes

,

-

-

Iliopsoas Compartment: Norma! Anatomy and Patho!ogic 1 Gladys Abbitt, Steven

M Torres, MD #{149} Joseph MD #{149}Patricia j Mergo, Fernandez, MD #{149}Pablo

The iliopsoas greater psoas, cesses

may

compartment smaller psoas, involve

the

creasing

incidence

is an extraperitoneal and iliac muscles.

iliopsoas

hemorrhagic, and neoplastic ally due to direct extension

G. Cernigliaro, MD #{149} Vas/iti R. Ros, MD

compartment,

MD #{149}Patricia F Hellein, MD

L.

space that contains Many pathologic pro-

the

including

conditions. Psoas muscle from contiguous structures.

of tuberculosis,

the majority

inflammatory,

infection is usuWith the de-

of psoas

abscesses

now

encountered have a pyogenic origin. Hemorrhage into the psoas muscle can be spontaneous or secondary to various conditions. Neoplastic involvement of the psoas muscle is usually due to contiguous spread and is rarely primary. With the refinement of imaging modalities, there has been increased recognition of diseases that involve the iiopsoas cornpartment. Although these conditions may look similar radiologically, they can be correctly diagnosed by combining the radiologic findings with the clinical history. Biopsy is effective in diagnosis of such condi-

tions;

aspiration

and drainage

are effective

in both

diagnosis

and ther-

apy.

.

INTRODUCTION

The iliopsoas compartment is composed of a group of extraperitoneal muscles that extend from the posterior mediastinum to the hip joint (1-3). They function as the primary flexors of the thigh and the trunk. The most common pathologic processes involving this compartment are inflammatory processes, hemorrhagic processes, and neoplasms (metastatic neoplasms, which are usually due to contiguous spread, and rare primary liposarcoma, fibrosarcoma, and leiomyosarcoma) (1-4). The purpose of this article is to review the normal anatomy of the iliopsoas compartment and a gamut of disease processes that involve the iliopsoas compartment onstrated with cross-sectional imaging, including computed tomography (CT), netic resonance (MR) imaging, and ultrasonography (US).

Index

terms:

Retroperitoneal RadioGraphics I

From

the

3261()-0374. requested , RSNA.

Muscles, space. 1995;

Department Presented April 14 and

iliopsoas. hemorrhage.

874.92 874.4

#{149} Muscles,

1 34

psoas,

874.92

#{149} Retroperitoneal

#{149} Retroperitoneal

space,

space.

neoplasms,

abscess.

874.211,

as demmag-

874.23

1

874.30

15:1285-1297 of Radiology,

University

as a scientific received May

exhibit at the 1994 RSNA scientific assembly. 3 1 ; accepted June 1 . Address reprint requests

of Florida

College

of Medicine,

160()

SW Archer

Rd. Gainesville,

Received Februars’ to G.M.T.

3. 1995:

FL revision

1995

1285

a. Figure greater

1. Normal iliopsoas compartment anatomy. (a) Drawing shows psoas and iliac muscles extend from the region of the diaphragm

a frontal inferiorly

view of the abdomen. The to the lesser trochanter of msec = 4,000/91) of the abdo-

the femur. (b) Coronal T2-weighted MR image (repetition time msec/echo time men shows the psoas muscle originating from the transverse process of T-1 2 (white riorly to merge with the iliac muscle, becoming the iiopsoas muscle (black arrows).

a.

arrows)

and extending

infe-

b.

Figure 2. 26-year-old

Abscesses man with

(a) Contrast

secondary a soft-tissue

material-enhanced

to tuberculous mass of the

CT scan

shows

infection right

in a

flank. bilateral cen-

lesions of low attenuation with ring enhancement (arrows) in the psoa muscle. (b, C) Axial (b) and sagittal (c) gadolinium-enhanced fat suppression MR images (800/IS) show bilateral low-signal-intensity lesions with ring enhancetral

ment heads

consistent in

with

psoas

abscesses

(arrows

in b, arrow-

C).

C.

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Exhibit

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15

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6

a.

b. Figure 3. Left-sided tuberculous abscess and Pott disease in a 60-year-old cachectic woman with a leftsided inguinal mass and fever. Contrast-enhanced CT scans show an extensive fluid collection of low attenuation with ring enhancement (arrow) that extends from the left greater psoas muscle (a) to the left iliac muscle (b) and the left inguinal region (C). There is associated bone destruction and extension to the epidural space (arrowhead in a). The diagnosis was confirmed with US-guided aspiration and drainage.

kidney, bowel loops, decreasing incidence ity of psoas abscesses

C.

pyogenic

. IUOPSOAS

The iliopsoas compartment consists of all of the muscles covered by the iliopsoas fascia including the greater psoas, smaller psoas, and iliac muscles (Fig 1 The iliac muscle arises from the iliac wing and inserts into the psoas tendon and the lesser trochanter of the femur. The greater psoas muscle originates from the transverse processes of T-1 2 and the lumbar vertebrae and extends inferiorly to merge with the iliac muscle at the L-5-S-2 level, becoming the ).

muscle.

The

iliopsoas

muscle

beneath the inguinal ligament lesser trochanter of the femur (1-6). The smaller psoas muscle is muscle located anterior to the muscle. It arises from the sides and the fibrocartilage between muscle

serts

into

nominate

ends the

in the

iliopectineal

bone

long,

1995

of abscesses

gion,

and

iliopsoas

eradication

cade, nant

in the

the

spine,

most

compartment.

of tuberculosis

common

paraspinal

over

the

iliopsoas

compartment

acquired

epidemic, culous

(1).

there

has

been

because

Tuberculosis

syndrome

a resurgence

infections

de-

predomiin the

However,

immunodeficiency

paraspinal

the

past

pyogenic abscesses became the cause of infected fluid collections

of the

re-

With

in tuber-

in industrialized of the

spine

(Pott

dis-

ease) may extend from the vertebral bodies into the paravertebral muscles and spread along the sheath of the psoas muscle to produce psoas

a long, slender greater psoas ofT-12 and L-1 them. Inferiorly,

abscesses.

flat eminence

tendon

that of the

inin-

DISEASES There are multiple causes of psoas muscle infection. It is commonly due to direct extension from contiguous structures such as the spine,

November

cause

countries.

passes

(2).

. INFLAMMATORY

. Tuberculous Abscesses In the past, tuberculosis was

to insert on the via the psoas ten-

don

this

(7).

COMPARTMENT

ANATOMY

iliopsoas

origin

and pancreas. With the of tuberculosis, the majornow encountered have a

guinal

This

region

struction, fluid the

infection

and

enlargement collections,

abscess

2, 3).

can

inguinal

of the and

rim

Manifestations

extend

nodes

may

psoas

associated be

seen

(8).

to the

in-

Bone

de-

muscle

calcification radiologically

of tuberculous

by of (Figs

spondylitis

that differ from those of pyogenic infections indude thickening or calcification of the abscess rim, multiple abscess cavities, and minimal new bone formation.

Torres

et al

U

RadioGraphics

I

1287

Figures 4, 5. (4) (a) Contrast-enhanced

Pyogenic

abscess

in a 24-year-old woman with a history of aplastic anemia and fever. a lesion of low attenuation in the inferior pole of the right kidney secondary to pyelonephritis (arrow). (b) Contrast-enhanced CT scan shows associated inflammatory changes extending to the anterior pararenal space and to the right psoas muscle (arrow). A urine culture was positive for yeast and gram-positive rods. (5) Pyogenic abscess in a 76-year-old woman with sepsis and a right flank mass after cholecystectomy. (a) Axial US scan shows a complex intrahepatic fluid collection (arrow) that displaces the right kidney anteriorly. (b) Contrast-enhanced CT scan shows anterior displacement of the right kidney by a complex fluid collection with ring enhancement consistent with an abscess (arrow) in the posterior pararenal space. The collection extends to the right psoas muscle region. Cultures of specimens from US-guided drainage showed growth of Escberichia coli.

CT scan shows

4b.

4a.

5a.

5b.

. Pyogenic Abscesses Pyogenic psoas abscesses are commonly seeondary to spread from adjacent inflammatory disease.

due

The

to direct

fections, ease,

bowel diverticulitis,

causes

spread

are

diverse;

from

infections appendicitis,

spinal such

most

cases

perforated

tive are

or epidural as Crohn

associated

with

Staphylococcus

organisms. On CT scans,

pyogenic

infections

mixed

are

gram-nega-

abscesses

manifest

as

co-

of low attenuation. When intravenously administered contrast material is used, ring enhancement may be seen with both CT and MR imag-

dis-

ing.

of the

Secondary

tissue

occasionally

gas

therapy

iliopsoas

findings

surrounding

guide

Exhibit

and

enlargement

(10) (Figs 4-9). age can be used

#{149} Scientific

muscle

aureus

in-

lon carcinoma, and perinephric abscesses. Primary abscesses rarely occur and are usually idiopathic (1 ,9). The most common organisms

1288

pSoaS

include

by

a lesion

obliteration

of

by inflammation

planes bubbles

and

CT-guided to confirm of psoas

muscle

bone

and

destruction

aspiration and the diagnosis

drainand to

abscesses.

Volume

15

Number

6

6-9.

Figures scess. within

(6) Pyogenic

abscess

in a 28-year-old

(a) CT scan shows air-filled loculi the enhancing rim of the left psoa

man

with collection muscles.

a history

of Crohn

disease

and

left

iliopsoas

ab-

and contrast material a fistula between the bowel and the iliopsoas muscle (arrow), consistent with the history of Crohn disease. (7) Pyogenic abscess in a 79-year-cdd man with duodenal perforation after sphincterotomy. CT scan shows multiple air hubbies and fluid within the right poa muscle, consistent with an abscess (arrow). (8) Pyogenic abscess in a 65-year-ld man with a history of diabetes and new onset of fever. CT scan shows enlargement of the right psoas muscle and associated bilateral fluid collections (arrowheads) with air bubbles in the left psoa muscle, consistent with an abscess. Cultures of aspirated purulent fluid showed growth of F coil. (9) Pyogenic abscess in a 79-year-1d man with a recently placed aortohifemoral graft who developed graft infection. Contrast-enhanced CT scan shows a lesion of low attenuation within the right psoas muscle (arrow) with associated periaortic and mesenteric inflammatorv changes and adenopathy, consistent with graft infection (arrowheads).

6a.

(arrow), a fluid and iiopsoas

of low attenuation, (b) CT scan shows

6b.

9.

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Figures 10, 11. (10) Spontaneous retroperitoneal bleeding in a 42-year4ld woman receiving warfarin sodium ((;ouniadin: I)u Pont Merck Pharmaceutical, Wilmington, 1)el). CT scan shows enlargement of the left psoas niuscie and a fluid-fluid interface with dependent layering of material of higher attenuation, suggestive of settling of blood elements (heniatocrit effect) (arrow). (11) Coagulopathy in an 81-year-old man after placement of an aortobifemoral graft. Nonenhanced CT scan shows a huge left-sided retroperitoneal collection of mixed attenuation.

toma

.

Arets

abutting

attenuation are mixed the left psoas muscle.

with

HEMORRHAGE

Hemorrhage

bleeding

the

psoas

muscle

can

be

spon-

to trau-

or secondary

diathesis,

inflammatory

anticoagulant

disease,

therapy, or recent surgery

tumor,

attenuation

dc.

hyper-

the

field

images: peripheral

sity

On

sion

signal

(Figs

a fluid-fluid 10-14). with

an

level

(hematocrit

Chronic abscess

aspiration

effect)

hematoma or necrotic may

be

may mass,

necessary

intensity

be

rounded

and

T2-weighted

used.

layers

signal

than

acute

that

inten-

mus-

of

hematoma

is

depending

Subacute

of signal

hematoma intensity

on

a low-intensity rim, a highzone, and a medium-inten-

T2-weighted

images,

core increases zone. As the of the

core

by a hypointense images

hema-

the

relative hematoma

signal

in-

to that ages,

of the

diminishes;

it is stir-

rim

Ti-

on both

and

(2).

to

differentiate them (10). The MR imaging appearance of hemorrhage depends on the age of the hematoma. Acute hematoma has a nonspecific MR imaging appear-

Exhibit

core.

distinct

tensity of the the peripheral

the

less

or hypoattenuating,

Ti-weighted intensity

with

slightly

images,

magnetic

three

with

images,

to or

On T2-weighted

slightly on

consistent

On Ti-weighted

sity is similar

Hematomas tei’id to involve the iliopsoas niuscle diffusely. Hemorrhage may infiltrate the muscle, causing enlargement or resulting in a discrete mass of high attenuation on CT scans. CT may show a hyperattenuating lesion or a Ic-

percutaneous

Scientific

of high

has

confused

U

material

or biopsy.

(2,3)

1290

some

ance.

into (arteriosclerosis)

ttI1eOUS

ma,

of low

(arrows)

U NEOPLASMS Neoplastic

involvement

most

secondary

often

of the to direct

psoas extension

muscle

is of pri-

mary mors noma,

retroperitoneal abdominal or pelvic tusuch as colon carcinoma, ovarian carciuterine carcinoma, cervical carcinoma, urinary tract tumor, and sarcoma; direct inva-

Volume

15

Number

6

12.

13. Figures

12-14.

(12)

bleeding in a 64-year-ild scan shows a ruptured extending to the psoas duodenal clot (13) Hematoma

Upper

gastrointestinal

man. aortic

tract

Contrast-enhanced aneurysm

muscles

with

(arrowheads)

(arrows) from an aortoenteric in an 81-year-old man after

CT bleeding

and a fistula. a left ne-

phrectomy. tenuation (arrows). man after

CT scan shows a large mass of high atthat diffusely involves the left psoas muscle (14) Decreasing hematocrit in a 48-year-old left renal artery angioplasty. CT scan shows a large perirenal collection of high attenuation that displaces the left kidney anteriorly, consistent with hematoma. There is enlargement of the left psoa muscle and the Gerota fascia secondary to hemorrhage (arrow).

sion

from

phoma;

such

cies

adjacent

lymph

or hematogenous

melanoma. Typical

as lung

Primary primary

cancer,

nodes,

as in lym-

spread

of malignan-

breast

intrinsic tumors

The

barrier psoas

November

retroperitoneal

masses

of the

liposarcoma, fibrosarcoma, tent-leiomyosarcoma and toma (4,1 1). fascial

cancer, psoas

and

are

regular

rare.

muscle

planes

offer

findings are

and-to a lesser hemangiopericy-

to tumors; therefore, involvement muscle may be extensive. Features

1995

lignancies sociated

cx-

include a history of neoplasm retroperitoneal lymphadenopathy, margins, and bone destruction. have

also

been

seen

in abscesses

or as-

irThese and

hematomas. Radiologic differentiation of psoas muscle tumors can be difficult, and aspiration or core biopsy may be needed to determine the diagnosis (4, 1 1 ) (Figs I 5-27).

no

of the of ma-

Torres

et al

#{149} RadioGraphics

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17. Figures

who

18. 15-18. presented

(15) Carcinoma in a 31-year-old man with a history of acquired immunodeficiency syndrome with low back pain and inguinal lymphadenopathy. Contrast-enhanced CT scan shows extensive

hypoattenuating retroperitoncal lymphadenopathy that encases the aorta and inferior vena cava and extends around the P5I5 muscle anteriorly (arrows). Results of CT-guided percutaneous biopsy were consistent with metastatic testicular emhrvonal cell carcinoma. (16) Lymphoma in a 76-year-old man. Contrast-enhanced CT scan shows enlargement of the right psoas muscle secondary to infiltration by soft-tissue masses anterior (curved arrows) and lateral to the psoa muscle and extending to the iliopsoas muscle, consistent with retroperitoneal lymphadenopathy. There is also mesenteric and greater omental lymphadenopathy (straight arrows). Results of CT-guided percutaneous biopsy were consistent with lymphoma (non-Hodgkin). (17) Carcinoma in a 44-)’ear-ild WOffLtfl with a history of cervical carcinoma. Contrast-enhanced CT scan shows a left-sided para-aortic soft-tissue mass with associated areas of low attenuation (arrow) that infiltrates the left psoas muscle. The bypoattenuating center, which represents necrotic tissue, may cause the tumor to he mistaken for an abscess or hematoma. (18) Liposarcoma in a 39-year-cld Womafl with right flank fullness. Contrast-enhanced CT scan shows a 111a55 of heterogeneous (fat and soft-tissue) attenuation (arrows) that surrounds and anteriorly displaces the right kidney and abuts the right psoa muscle. Results of histologic analysis were consistent with liposarcoma.

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b.

a.

Figure

19.

Liposarcoma

in a 71-year-old

woman

with a history of myxoid liposarcoma of the left kidney. (a) Contrast-enhanced CT scan shows an enhancing necrotic mass that infiltrates the left psoas muscle and the descending colon (arrow). A cyst is incidentally

seen

in the

lower

pole

head). (b) Axial Ti-weighted hypointense infiltrative mass

of the

right

kidney

(arrow-

image (300/1 that involves

5) shows the left

psoas muscle (arrows). (C) Axial T2-weighted (2,000/90) shows increased signal intensity mass (arrows), compatible with a neoplastic Biopsy of the mass demonstrated recurrent

image of the process. sarcoma.

a

C.

Figure

20.

man.

CT scan

Leiomyosarcoma in a 54-year-cdd woshows a round, left-sided retroperitoneal mass of mixed attenuation that extends from the left para-aortic region to the left psoas muscle (arrow) and inferiorly to the pelvic region. The lesion appears

to be extrinsic

to the psoa5

to be a leiomyosarcoma

November

1995

muscle.

of fallopian

Torres

et al

This was proved tube

U

origin.

RadioGrapbics

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Figure 21. Skiti neurofibromas in a 21-year-old man. (a) CT scan shows large intrapsoas masses of low attenuation with associated enlargement of the neural foramen (arrow), consistent with neurofibromas. (b) CT scan shows multiple rounded, nodular masses within the spinal canal, mesentery, and retroperitoneum (arrows). These findings are pathognomonic for neurofibromatosis. The intrapsoas location is due to involvement of the lletVe5 of the lumbar plexus, which traverse the psoa muscle.

22.

23.

Figures

22, 23. (22) Retroperitoneal sarcoma invading the iliopsoas compartment in a 69-year-old woman with a left flank mass. Contrast-enhanced CT scan shows a large, heterogeneous, retroperitoneal mass with scattered areas of low attenuation secondary to necrosis (arrow). The mass infiltrates the left psoas muscle and displaces the aorta toward the right. Results of biopsy of the mass were consistent with leiomyosarcoma. (23) Fibrosarcoma of the abdominal wall in a 46-yearnld man. Contrast-enhanced CT scan shows a right-sided soft-tissue mass of the abdominal wall with areas of low attenuation and wall enhancement (arrow). The tumor extends from the abdominal wall to the right psoas muscle. The clinical history and percutaneous biopsy were necessars’ to differentiate this tumor from other processes, such as an abscess.

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Figures 24, 25. (24) Metastasis in a 65-year-old man with a history of transitional cell carcinoma of the bladder. Contrast-enhanced CT scan shows a markedly enlarged left psoa muscle with a central area of low attenuation (arrow). Complicated processes such as infected or hemorrhagic tumors may have this appearance. Results of percutaneous biopsy were consistent with metastatic transitional cell carcinoma. (25) Recurrent tumor in a 62-year4dd man after a left nephrectomy for renal cell carcinoma. Contrast-enhanced CT scan shows two rounded masses within the left renal fossa that extend to the left psoas muscle (arrow). The masses were consistent with recurrent renal cell carcinoma.

26a.

26b. Figures year-old shows

26, 27. woman. enlargement

displacement lobulated age (300/1 sity within

melanin

(26) (a)

Melanoma

(arrow).

(27)

Pseudomyxoma

man

enocarcinoma.

Contrast-enhanced

appendix

with filled

a history with

tumor

retroperitonei of appendiceal

ad-

CT scan

an

(arrow).

of low attenuation that involves the iliopsoas (arrowheads) is seen adjacent to the appendix: mass was proved retroperitonei.

November

1995

in a 52-

CT scan muscle with

of the retroperitoneal vessels by a solid, mass (arrow). (b) Axial Ti-weighted MR im5) shows an area of increased signal intenthe mass due to the paramagnetic effect of

in a 53-year-old enlarged

metastasis

Contrast-enhanced of the right psoas

to represent

Torres

shows

A mass

muscle this

pseudomyxoma

et al

#{149} RadioGraphics

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a.

b.

Figure 28. Retroperitoneal man. (a) Contrast-enhanced l)eritoneLl

fibrosis CT scan

in a 60-year-old shows a retr()-

that encases the inferior vena cava and inflitrates the left psoas muscle. (b) Axial 1’2-weighted MR image (2,000/90) shows mildly increased signal intensity within the retroperitoneal mass (arrows). (c) Axial gadolinium-enhanced fat saturation MR image (800/1 4) shows minimal contrast enhtncement (arrows). Use of contrast material allows excellent demonstration of the fibrosis stirrounding the left psoas muscle. and

mass

aorta

(arrow)

U MISCELlANEOUS Retroperitoneal )aralysis secondary other

that (Figs

secondary

to

may

involve

the

C.

iliopsoas hemorrhagic,

28-30).

CONCLUSIONS

There

arc

many

pathologic

ration

extension

l)ortion bellies

of disease

of the compartment for an extensive

that

processes

the iliopsoas compartment. of the iliopsoas compartment

volve the

(12)

atrophy

and muscle calcification or rhabdomyolysis are

to trauma conditions

muscle

.

fibrosis, or disease,

processes down

distance.

The

in-

configu-

facilitates from the

one muscle

Inflammatory,

and

volve

the

cally,

these

when

the

with

can

the

conditions

been

involve used

such

to guide

iliopsoas biopsy

procedures

look

similar;

are

the

the

as CT

increased

the

drainage

may

history,

With

correct

MR

diagnosis

of imaging imaging,

recognition

for

both

there

of diseases

compartment. as well

but

combined

refinement and

in-

may

Radiologi-

findings

clinical

be made.

conditions

compartment.

radiologic

modalities has

neoplastic

iliopsoas

that

CT can

as aspiration diagnosis

be and

and

therapy.

1296

#{149} Scientific

Exhibit

Volume

15

Number

6

29.

30.

Figures lateral muscle

29,

30.

(29)

fat-infiltrated is an atrophic

neural

psoas muscles kidney with

a long-standing

history

rows). Muscle sis(9).

calcification

S

Congenital

of renal

secondary calcifications

failure.

in renal

tube

defect

in an 18-year-old

Nonenhanced

failure

is rarely

CT scan seen

and

shows

2.

3.

4.

5.

6.

7.

I)onovan JP, Zerhouni EA, Siegelman SS. CT of the psoas compartment of the retroperitoneum. Semin Roentgenol 1981: 16:241-250. Lee JK, Sagel SS, Stanley RJ. Computed body tomography with MRI correlation. New York, NY: Raven, 1989; 746-750. Lenchick L, Dovgan DJ, Kier R. CT of the ilioSO5 compartment: value in differentiating tumor, al)scess, and hematoma. AJR 1994; 162: 83-86. Feldberg MAM, Koehler PR. Van Waes PFGM. Psoas compartment studied by computed tomography. Radiology 1 983: 148:0-12. Meyers MA. Dynamic radiology of the abdomen: normal and pathologic anatomy . 3rd ed. New York, NY: Springer-Verlag, 1988; 41452. Van I)yke JA, Hollev HC. Anderson SD. Review of the iliopsoas anatomy and pathology. RadioGraphics 1987: 7:53-85. Schreiher MH, Cavallo FM, Dominguez yE, et

November

1995

bilateral

may he associated

REFERENCES 1.

woman.

Nonenlianced

to disuse (arrow). The soft-tissue mass (arrowhead). (30) Muscle calcification

psoas with

CT scan

shows

hi-

adjacent to the left psoas in a 10-year-old boy with

muscle

calcitications

nontraumatic

(ar-

rhahdoniyoly-

Iniage interpretJtion session: 1992. Radio(;raphics 1993; 13:169-192 (case 2). Cotran RS, Kuniar V. Robbins SL. Robbins pathologic basis of disease. 4th ed. Philadelal.

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l)hia,

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I 2.

Pa: Saunders,

Oliff M, Chuang

1989;

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iliac fossa pyogenic abscesses. Radiology I 978: 126:647-6S2. RaIls PW, Boswell W, Henderson R, Rogers W, Boger D, Halls j. CT of inflammator\’ disease of the psoas muscle. AJR 1980: l34:767-’0. Kenny jB, Widdowson I)J, Cart AT, Williams CE. Malignant involvement of the iliopsoas muscle: CT appearances. Eurj Radiol 1990: 10:183-187. Towers Mj, I)owney 1)13. Poon PY. Psoas musdc calcification and acute renal failure assoCiated with nontraumatic rhabdomvolvsis: CT features. J Comput Assist Tomogr 1990; 14: 102-lt)29.

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