Australas Radio1 1992;36: 334-338
I
Neoplastic involvement of the sacroiliac joint: MR and CT features M. SILBERSTEIN, M.B., B.S. AND 0. HENNESSY, F.R.C.R. Department of Radiology Austin Hospital, Victoria,Australia. L.LAU,F.R.A.C.R. Diagnostic Imaging Group Glenroy, Victoria,Australia.
ABSTRACT The radiological findings in five patients with pelvic sort tissue neoplasms directly involving the sacroiliac joint, are described. All patients had Computed Tomography (CT) examinations, two of the patients also having Magnetic Resonance Imaging (MRI).The role of imaging in this uncommon entity is discussed as well as the importance of making this diagnosis, thereby excluding unilateral sacroiliitis. The therapeutic implications of this diagnosis relate to local neural involvement, especially the sciatic nerve, and the fact that involvement of the sacroiliacjoint by tumors significantly compromises chances of a successful surgical outcome. The role of MR in this condition is not yet certain, but it may prove to be the method of choice in view of its excellent depiction of skeletal neoPINTRODUcIloN Although joint cartilage acts as a relative barrier to neoplastic spread from subarticular bone, no such banier exists against involvement of a nearby joint space by aggressive soft tissue neoplasms arising close to joints. Such involvement at the sacroiliac joint could mimic sacroiliitis on plain films and, in addition, would significantly compromise the chances of successful surgical out
F'IGURE 1A - Synovial Cell Sarcoma. CT shows large soft tissue mass extending from right gluteal fossa into pelvis with erosion of margins of sacroiliacjoint.
come. Magnetic resonance imaging of the sacroiliac joint has only been considered relatively recently, with descriptions of normal appearances (l), and septic sacroiliitis (2), appearing in the literature. The clinical history and radiological fmdings in five patients with neoplastic involvement of the sacroiliac joint are presented, the first two of whom had magnetic resonance imaging (MRI). The role of conventional radiography, computed tomography (cr)and magnetic resonance imaging (MRI) are discussed. CASE REPORTS
Key wwds:
Case I
MRI-CT Addrrssforeorrrspoadenee: Dr M.Silberstein Department of Radiology Austin Hospital Heidelbag. Victoria
A 20 year old man presented with a six week history of increasing pain in the right buttock. At physical examination there was the suggestion of a deep soft tissue mass in the right gluteal region and no other abnormality.
Neoplasm - Sacroiliacjoint
Australia3084
334
CT showed a nine by six by four centimetre soft tissue density mass in the right gluteal fossa extending into the pelvis via the greater sciatic foramen with erosion of the margins of the sacroiliac joint, and displacement of the rectum to the left (Figure 1A). At MRI the mass was of low signal intensity on T1 and high signal intensity on T2-weighted SE images. As well as extension through gluteal and pyriformis muscles, displacement of the sciatic neurovascular bundle and the rectum were present (Figures 1B and 1C). Microscopic examination of a biopsy specimen showed groups of small spindle cells with marked cellular atypia and prominent clefts between cellular groups, consistent with synovial cell sarcoma.
Submined for publication on: 10th September. 1991 Accepted for publication on: 171h December. 1991
Australasian Radiology, Vol. 36. No. 4 , November. 1992
NEOPLASTIC INVOLVEMENT OF THE SACROILIAC JOINT
FIGURE 1B -Coronal TI-weighted MR image shows low signal intensity mass eroding lower margin of sacroiliac joint and displacing rectum to left.
Case 2 A 34-year-old man presented with a four week history of increasing lower abdominal pain, intermittent constipation, and tenesmus. Physical examination revealed a hard extrinsic mass palpable anteriorly per rectum. Cpnventional radiographs showed subtle erosion of the left sacroiliac joint. CT showed a very large multi16bulated enhancing mass with internal septation, cystic areas, and a small area of calcification, in a presacral location, displacing the bladder and
FIGURE 1C - Axial T2-weighted M R image shows high signal imcnSily mass extending through gluteal muscle and ilium into sacroiliac joint.
rectum anterosuperiorly and eroding the left sacroiliac joint (Figure 2A). On MRI the mass was of heterogeneous signal with low intensity on T1and high signal intensity on T2weighted images (Figures 2B and 2C). Erosion of the left sacroiliac joint was clearly visualized as was the relationship to pelvic viscera and muscles. The area of calcification was not visible. Microscopic examination showed sheets of slender elongated cells with palisading of nuclei consistent with a Schwannoma.
FIGURE 2.4 - Schwannorna. CT shows large pelvic soft extending into sacrum and left sacroiliac p i n t . Australasian Radiology, Vol.36. No. 4, Novetnber, 1992
tissue mass
Case 3
A 60-year-old woman with known neurofibromatosis presented with a four month history of parasthesiae in the left calf and foot. physical examination revealed foot-drop, an area of anaesthesia in the L5-SI dermatome, and weakness of foot extension on the left side. Conventional radiographs showed erosion of the left sacroiliac joint. CT showed a large soft tissue mass eroding in the left sacroiliacjoint and extending through the greater sciatic foramen into the gluteal fossa
FIGURE 2B - Axial TI-weighted MR image shows multilobulated slightly hypointense p r c s m l mass with separate lobule in left sacral ala. crossing sacroiliac joint.
335
M. SILBERSTEIN er a1 pain. At physical examination, he had focal tenderness over the right sacroiliac joint. Conventional radiographs showed erosion of the right sacroiliac joint. CT showed lytic areas involving both sides of the joint with erosion of the articular cortex of both sacrum and ilium (Figure 4). A large soft tissue mass was present around the ilium as well as extensive iliac bone destruction. Microscopic examination of a biopsy specimen was consistent with a chondrosarcoma.
AGURE 2C - PamsagittalT2-weighted M R image clearly shows vertical and axial dimensions of the high signal intensity mass with components in pelvis and gluteal fossa.
Case 5 A 46-year-old man with a six year history of Paget's disease presented with a four week history of increasing left calf pain and increasing limp. At physical examination, there was reduced power of foot extension on the left and an area of anaesthesia over the left calf. CT showed a large low attenuation mass adjacent to the left ilium with erosion of both ilium and left sacroiliac joint, and extension from the pelvis into the gluteal region across the greater sciatic foramen (Figure 5).
Microscopic examination of a biopsy specimen showed undifferentiated carcinoma, primary source unknown. At postmortem, three weeks following presentation there was widespread dissemination, both bony and visceral by carcinoma, as well as changes of Paget's disease of bone.
DISCUSSION
FIGURE 3 - Neorofibmsarcana (JT shows h e soft tissue mass extending from pelvis into left gluteal fossa cross s ~ ~ o i l i joint. ac
(Figure 3). The bladder and rectum were displaced to the right, and diffuse expansion of the sacral canal was noted.Whilst in hospital she developed pneumonia and died. At post-mortem she was found to have multiple neurofibromata, and at microscopy, the pelvic mass showed numerous spindle cells with nuclear atypia and
336
local bone and muscular invasion consistent with neurofibrosarcoma. Case 4 A 38-year-old man with a past history of a chondrosarcoma of the humerus treated by amputation three years previously, presented with two weeks of increasing right lower back
Traditional radiological and paths logical teaching is that cartilage i s a relative banier to neoplastic spread so that involvement of joint spaces by tumors is very rare (3, 4). A recent review of the radiological literature identified a total of 4 3 cases of transarticular invasion by tumors in the axial skeleton, with the sacroiliac articulation the most frequent joint involved (3). Although MR imaging was performed in 2 of these cases,, specific descriptions of MR of neoplastic invasion of the sacroiliac joint have not previously been' published. The sacroiliac joint is predominantly synovial, with a small fibrous component (5). By virtue of its anatomic relationships, nearby tumors have widespread pathological effects. As well as pelvic viscera, the joint is closely related to the lumbosacral and pelvic nerves and, in particular, the sciatic nerve exiting via the greater sciatic foramen (5). The significance of joint involvement is twofold. Firstly, the plain film
Ausriralasian Radiology. Vol. 36. No. 4 . November, 1992
NEOPLASTIC INVOLVEMENT OF THE SACROILIAC JOINT recently CT has been described by several authors as a valuable technique in the assessment of sacroiliitis (10,ll). and most recently reports of MRI of septic sacroiliitis have appeared ( 12). All of our patients had CT which clearly demonstrated bone involvement as well as adjacent soft tissue masses. The two patients who had MRI had excellent demonstration of soft tissue masses, including internal characteristics, relationship to muscles, fat planes, vessels and pelvic viscera, as well as sacroiliac joint and adjacent bone involvement. In one patient (Case 2), MR failed to reveal an area of calcification in the tumor.
FIGURE 4 - Metamstatic chondrosarcoma CT of pelvis (patient prone) shows two lytic lesim in right ilium, one of which involves the sacroiliac joint.
’ FIGURE 5 - Metastatic carcinoma CT shows large low attenuation mass extending through greater sciatic foramen with involvement of anterior aspect of sacroiliac joint. Note expansion and sclerosis , of righr ilium consistent with Paget’s diseases.
appearances could mimic sacroiliitis, and secondly, involvement of the sacroiliac joint by neoplasm has major therapeutic consequences as curative resection is likely to be impossible, and local problems relating to neural involvement, especially the sciatic nerve, are likely to develop. In our patients, there were probably two mechanisms by which sacroiliac joint involvement occurred. Cases 1 to 3, although including a patient with a benign tumor (Case. 2), all had very
large soft tissue masses located in fascial planes outside the joint, so that spread to the joint may have through the joint capsule, avoiding the relative barrier of articular cartilage. In Cases 4 and 5, the neoplasms wzre agressive metastases, situations in which other authors have previously described direct spread across articular cartilage (6,7,8,9). Whereas plain films were, for many years, the “gold standard for investigation of the sacroiliac joints, more
Australasian Radiology, Vol. 36. No. 4. November. 1992
MRI has been shown to be better than or equal to CT for imaging soft tissue extent, bone marrow involvement and neurovascular involvement in neoplasms involving bone (13, 14, 15). Although less accurate than CT for demonstration of cortical bone involvement and tumor calcification, MRI is equal to or better than CT for demonstrating joint involvement. In one study of 17 patients with joint involvement by neoplasm in the appendicular skeleton, both CT and MR had close to 95% accuracy in depicting joint invasion (16). while in another study of 29 patients who had joint involvement by neoplasm, hfR was judged to be better than or equal to CT in 97% of cases (17). Patients with pelvic neoplasms of bone usually require C T for internal characterization of the tumor prior to resection due to the often incomplete imaging of neoplasms of the bony pelvis on plain films (16, 18). Although subtle soft tissue invasion is better seen on MR, and subtle bony erosion is better seen on CT,only one of these modalities will usually be required for characterization of neoplasms involving bone (15). As demonstrated in this series, and those of others (3), transgression of joint space will not distinguish benign from malignant bone tumors, but there is some evidence to suggest that the use of a combination of MR criteria including signal intensity and homogeneity, tumor margin, neurovascular invasion, signal changes in adjacent soft tissue, growth rate, size, location and bone destruction, may make this distinction possible (15). CONCLUSION Although specific descriptions of magnetic resonance imaging of neoplastic involvement of the sacroiliac 337
M. SILBERSTEIN et a1 joint have not previously appeared in the literature, its recognition is of major diagnostic and therapeutic importance. Although not, as yet, replacing CT in the imaging of this condition, the ability of MRI to display this joint and its utility in imaging soft tissue neoplasms may, in the future, make it the method of choice in investigation of this entity.
5.
6. 7.
8.
REFERENCES Forrester DM. Imaging of the sacroiliac joints. Rad Clin North Am 1990; 28: 1055-1061. Klein MA, Winalski MR, Piwnica-Worms DR. MR imaging of septic sacroiliitis, J Comput Assist Tomog 1991: 15: 126-132. Abdelwahab IF, Miller lT,Hermann GH, Klein MJ, Kenan S, Lewis MM. Transarticular invasion of joints by bone tumors: hypothesis. Skelet Rad 1991; 20: 297-283. Walter JB, Israel MS. General pathology, 6th ed. Edinburgh: Churchill Livingstone 1987: 387-388.
338
9. 10.
11.
12.
Wanvick R, Williams PL. Gray’s Anatomy. 35th ed. Edinburgh: Longman 1973: 342-243. Kagan AR,Steckel RJ. Metastatic carcinoma presenting as shoulder arthritis. AJR 1977; 129: 137-141. Meals RA, Hungerford DS, Stevens MB. Malignant disease mimicking arthritis of the hip. JAMA 1978; 239: 1070-1073. Nubbard DD, Gunn DR. Secondary carcinoma of the spine with destruction of the intervertebral disk. Clin Orthop Re1 Res 1972: 88: 86-90. Resnick D, Niwayama G. Diagnosis of bone and joint disorders. Philadelphia: WB Saunders 1981: 2773-2781. Camissa M. Lomuto M, Bonetti MG. Sacroiliitis in seronegative polyarthritis: CT analysis, Clin Exp Rheumatol 1987; 5(Suppl I): S105-SlO7. Van Tieeelen R. Sacroiliitis: difficulties in the rad%graphic diagnosis: advantage of CI? Preliminary report. J Belge Rad 1987; 70: 14. Wilbur AC, Langer BG, Spigos DG. Diagnosis of sacroiliac joint infection in pregnancy by magnetic resonance imaging case report. Magn Res h a g 1988; 6: 341-343.
13. Dalinka MK, Zlatkin MB, Chao P et a/. The use of magnetic resonance imaging in the evaluation of bone and soft tissue tumors. Rad Clin North Am 1990; 28: 46 1 -467. 14. Gold RI. Seeger LL, Bassett LW ef ul. An integrated approach to the evaluation of metastatic bone disease. Rad Clin North Am 1990; 28: 471479. 15. Sundaram M, McLeod RA. MR imaging of tumor and tumorlike lesions of bone’ and soft tissue. AJR 1990; 155: 817-824. 16. Bloem JL, Taminiau AH, Eulderink R er al. Radiologic staging of primary bone sarcoma: MR imaging, scintigraphy and CT correlated with pathologic examination. Radiology -. 1988; 169: 805-810. 17. Wetzel LH, Levin E, ~~~~h~ MD. A comparison of MR imaging and CT in the evaluation of musculoskeletal masses. Radiographics 1987; 7: - 851-862. 18, Sundaram M, McGuire MH, Computed tomography or magnetic resonance for evaluating the solitarv tumor or tumorlike lesion 07 bone? Skklet Rad 1988; 17: 393-401.
AusfrakusianRudiologv. Vol. 36. No. 4. November, I992
I
Neoplastic involvement of the sacroiliac joint: MR and CT features M. SILBERSTEIN, M.B., B.S. AND 0. HENNESSY, F.R.C.R. Department of Radiology Austin Hospital, Victoria,Australia. L.LAU,F.R.A.C.R. Diagnostic Imaging Group Glenroy, Victoria,Australia.
ABSTRACT The radiological findings in five patients with pelvic sort tissue neoplasms directly involving the sacroiliac joint, are described. All patients had Computed Tomography (CT) examinations, two of the patients also having Magnetic Resonance Imaging (MRI).The role of imaging in this uncommon entity is discussed as well as the importance of making this diagnosis, thereby excluding unilateral sacroiliitis. The therapeutic implications of this diagnosis relate to local neural involvement, especially the sciatic nerve, and the fact that involvement of the sacroiliacjoint by tumors significantly compromises chances of a successful surgical outcome. The role of MR in this condition is not yet certain, but it may prove to be the method of choice in view of its excellent depiction of skeletal neoPINTRODUcIloN Although joint cartilage acts as a relative barrier to neoplastic spread from subarticular bone, no such banier exists against involvement of a nearby joint space by aggressive soft tissue neoplasms arising close to joints. Such involvement at the sacroiliac joint could mimic sacroiliitis on plain films and, in addition, would significantly compromise the chances of successful surgical out
F'IGURE 1A - Synovial Cell Sarcoma. CT shows large soft tissue mass extending from right gluteal fossa into pelvis with erosion of margins of sacroiliacjoint.
come. Magnetic resonance imaging of the sacroiliac joint has only been considered relatively recently, with descriptions of normal appearances (l), and septic sacroiliitis (2), appearing in the literature. The clinical history and radiological fmdings in five patients with neoplastic involvement of the sacroiliac joint are presented, the first two of whom had magnetic resonance imaging (MRI). The role of conventional radiography, computed tomography (cr)and magnetic resonance imaging (MRI) are discussed. CASE REPORTS
Key wwds:
Case I
MRI-CT Addrrssforeorrrspoadenee: Dr M.Silberstein Department of Radiology Austin Hospital Heidelbag. Victoria
A 20 year old man presented with a six week history of increasing pain in the right buttock. At physical examination there was the suggestion of a deep soft tissue mass in the right gluteal region and no other abnormality.
Neoplasm - Sacroiliacjoint
Australia3084
334
CT showed a nine by six by four centimetre soft tissue density mass in the right gluteal fossa extending into the pelvis via the greater sciatic foramen with erosion of the margins of the sacroiliac joint, and displacement of the rectum to the left (Figure 1A). At MRI the mass was of low signal intensity on T1 and high signal intensity on T2-weighted SE images. As well as extension through gluteal and pyriformis muscles, displacement of the sciatic neurovascular bundle and the rectum were present (Figures 1B and 1C). Microscopic examination of a biopsy specimen showed groups of small spindle cells with marked cellular atypia and prominent clefts between cellular groups, consistent with synovial cell sarcoma.
Submined for publication on: 10th September. 1991 Accepted for publication on: 171h December. 1991
Australasian Radiology, Vol. 36. No. 4 , November. 1992
NEOPLASTIC INVOLVEMENT OF THE SACROILIAC JOINT
FIGURE 1B -Coronal TI-weighted MR image shows low signal intensity mass eroding lower margin of sacroiliac joint and displacing rectum to left.
Case 2 A 34-year-old man presented with a four week history of increasing lower abdominal pain, intermittent constipation, and tenesmus. Physical examination revealed a hard extrinsic mass palpable anteriorly per rectum. Cpnventional radiographs showed subtle erosion of the left sacroiliac joint. CT showed a very large multi16bulated enhancing mass with internal septation, cystic areas, and a small area of calcification, in a presacral location, displacing the bladder and
FIGURE 1C - Axial T2-weighted M R image shows high signal imcnSily mass extending through gluteal muscle and ilium into sacroiliac joint.
rectum anterosuperiorly and eroding the left sacroiliac joint (Figure 2A). On MRI the mass was of heterogeneous signal with low intensity on T1and high signal intensity on T2weighted images (Figures 2B and 2C). Erosion of the left sacroiliac joint was clearly visualized as was the relationship to pelvic viscera and muscles. The area of calcification was not visible. Microscopic examination showed sheets of slender elongated cells with palisading of nuclei consistent with a Schwannoma.
FIGURE 2.4 - Schwannorna. CT shows large pelvic soft extending into sacrum and left sacroiliac p i n t . Australasian Radiology, Vol.36. No. 4, Novetnber, 1992
tissue mass
Case 3
A 60-year-old woman with known neurofibromatosis presented with a four month history of parasthesiae in the left calf and foot. physical examination revealed foot-drop, an area of anaesthesia in the L5-SI dermatome, and weakness of foot extension on the left side. Conventional radiographs showed erosion of the left sacroiliac joint. CT showed a large soft tissue mass eroding in the left sacroiliacjoint and extending through the greater sciatic foramen into the gluteal fossa
FIGURE 2B - Axial TI-weighted MR image shows multilobulated slightly hypointense p r c s m l mass with separate lobule in left sacral ala. crossing sacroiliac joint.
335
M. SILBERSTEIN er a1 pain. At physical examination, he had focal tenderness over the right sacroiliac joint. Conventional radiographs showed erosion of the right sacroiliac joint. CT showed lytic areas involving both sides of the joint with erosion of the articular cortex of both sacrum and ilium (Figure 4). A large soft tissue mass was present around the ilium as well as extensive iliac bone destruction. Microscopic examination of a biopsy specimen was consistent with a chondrosarcoma.
AGURE 2C - PamsagittalT2-weighted M R image clearly shows vertical and axial dimensions of the high signal intensity mass with components in pelvis and gluteal fossa.
Case 5 A 46-year-old man with a six year history of Paget's disease presented with a four week history of increasing left calf pain and increasing limp. At physical examination, there was reduced power of foot extension on the left and an area of anaesthesia over the left calf. CT showed a large low attenuation mass adjacent to the left ilium with erosion of both ilium and left sacroiliac joint, and extension from the pelvis into the gluteal region across the greater sciatic foramen (Figure 5).
Microscopic examination of a biopsy specimen showed undifferentiated carcinoma, primary source unknown. At postmortem, three weeks following presentation there was widespread dissemination, both bony and visceral by carcinoma, as well as changes of Paget's disease of bone.
DISCUSSION
FIGURE 3 - Neorofibmsarcana (JT shows h e soft tissue mass extending from pelvis into left gluteal fossa cross s ~ ~ o i l i joint. ac
(Figure 3). The bladder and rectum were displaced to the right, and diffuse expansion of the sacral canal was noted.Whilst in hospital she developed pneumonia and died. At post-mortem she was found to have multiple neurofibromata, and at microscopy, the pelvic mass showed numerous spindle cells with nuclear atypia and
336
local bone and muscular invasion consistent with neurofibrosarcoma. Case 4 A 38-year-old man with a past history of a chondrosarcoma of the humerus treated by amputation three years previously, presented with two weeks of increasing right lower back
Traditional radiological and paths logical teaching is that cartilage i s a relative banier to neoplastic spread so that involvement of joint spaces by tumors is very rare (3, 4). A recent review of the radiological literature identified a total of 4 3 cases of transarticular invasion by tumors in the axial skeleton, with the sacroiliac articulation the most frequent joint involved (3). Although MR imaging was performed in 2 of these cases,, specific descriptions of MR of neoplastic invasion of the sacroiliac joint have not previously been' published. The sacroiliac joint is predominantly synovial, with a small fibrous component (5). By virtue of its anatomic relationships, nearby tumors have widespread pathological effects. As well as pelvic viscera, the joint is closely related to the lumbosacral and pelvic nerves and, in particular, the sciatic nerve exiting via the greater sciatic foramen (5). The significance of joint involvement is twofold. Firstly, the plain film
Ausriralasian Radiology. Vol. 36. No. 4 . November, 1992
NEOPLASTIC INVOLVEMENT OF THE SACROILIAC JOINT recently CT has been described by several authors as a valuable technique in the assessment of sacroiliitis (10,ll). and most recently reports of MRI of septic sacroiliitis have appeared ( 12). All of our patients had CT which clearly demonstrated bone involvement as well as adjacent soft tissue masses. The two patients who had MRI had excellent demonstration of soft tissue masses, including internal characteristics, relationship to muscles, fat planes, vessels and pelvic viscera, as well as sacroiliac joint and adjacent bone involvement. In one patient (Case 2), MR failed to reveal an area of calcification in the tumor.
FIGURE 4 - Metamstatic chondrosarcoma CT of pelvis (patient prone) shows two lytic lesim in right ilium, one of which involves the sacroiliac joint.
’ FIGURE 5 - Metastatic carcinoma CT shows large low attenuation mass extending through greater sciatic foramen with involvement of anterior aspect of sacroiliac joint. Note expansion and sclerosis , of righr ilium consistent with Paget’s diseases.
appearances could mimic sacroiliitis, and secondly, involvement of the sacroiliac joint by neoplasm has major therapeutic consequences as curative resection is likely to be impossible, and local problems relating to neural involvement, especially the sciatic nerve, are likely to develop. In our patients, there were probably two mechanisms by which sacroiliac joint involvement occurred. Cases 1 to 3, although including a patient with a benign tumor (Case. 2), all had very
large soft tissue masses located in fascial planes outside the joint, so that spread to the joint may have through the joint capsule, avoiding the relative barrier of articular cartilage. In Cases 4 and 5, the neoplasms wzre agressive metastases, situations in which other authors have previously described direct spread across articular cartilage (6,7,8,9). Whereas plain films were, for many years, the “gold standard for investigation of the sacroiliac joints, more
Australasian Radiology, Vol. 36. No. 4. November. 1992
MRI has been shown to be better than or equal to CT for imaging soft tissue extent, bone marrow involvement and neurovascular involvement in neoplasms involving bone (13, 14, 15). Although less accurate than CT for demonstration of cortical bone involvement and tumor calcification, MRI is equal to or better than CT for demonstrating joint involvement. In one study of 17 patients with joint involvement by neoplasm in the appendicular skeleton, both CT and MR had close to 95% accuracy in depicting joint invasion (16). while in another study of 29 patients who had joint involvement by neoplasm, hfR was judged to be better than or equal to CT in 97% of cases (17). Patients with pelvic neoplasms of bone usually require C T for internal characterization of the tumor prior to resection due to the often incomplete imaging of neoplasms of the bony pelvis on plain films (16, 18). Although subtle soft tissue invasion is better seen on MR, and subtle bony erosion is better seen on CT,only one of these modalities will usually be required for characterization of neoplasms involving bone (15). As demonstrated in this series, and those of others (3), transgression of joint space will not distinguish benign from malignant bone tumors, but there is some evidence to suggest that the use of a combination of MR criteria including signal intensity and homogeneity, tumor margin, neurovascular invasion, signal changes in adjacent soft tissue, growth rate, size, location and bone destruction, may make this distinction possible (15). CONCLUSION Although specific descriptions of magnetic resonance imaging of neoplastic involvement of the sacroiliac 337
M. SILBERSTEIN et a1 joint have not previously appeared in the literature, its recognition is of major diagnostic and therapeutic importance. Although not, as yet, replacing CT in the imaging of this condition, the ability of MRI to display this joint and its utility in imaging soft tissue neoplasms may, in the future, make it the method of choice in investigation of this entity.
5.
6. 7.
8.
REFERENCES Forrester DM. Imaging of the sacroiliac joints. Rad Clin North Am 1990; 28: 1055-1061. Klein MA, Winalski MR, Piwnica-Worms DR. MR imaging of septic sacroiliitis, J Comput Assist Tomog 1991: 15: 126-132. Abdelwahab IF, Miller lT,Hermann GH, Klein MJ, Kenan S, Lewis MM. Transarticular invasion of joints by bone tumors: hypothesis. Skelet Rad 1991; 20: 297-283. Walter JB, Israel MS. General pathology, 6th ed. Edinburgh: Churchill Livingstone 1987: 387-388.
338
9. 10.
11.
12.
Wanvick R, Williams PL. Gray’s Anatomy. 35th ed. Edinburgh: Longman 1973: 342-243. Kagan AR,Steckel RJ. Metastatic carcinoma presenting as shoulder arthritis. AJR 1977; 129: 137-141. Meals RA, Hungerford DS, Stevens MB. Malignant disease mimicking arthritis of the hip. JAMA 1978; 239: 1070-1073. Nubbard DD, Gunn DR. Secondary carcinoma of the spine with destruction of the intervertebral disk. Clin Orthop Re1 Res 1972: 88: 86-90. Resnick D, Niwayama G. Diagnosis of bone and joint disorders. Philadelphia: WB Saunders 1981: 2773-2781. Camissa M. Lomuto M, Bonetti MG. Sacroiliitis in seronegative polyarthritis: CT analysis, Clin Exp Rheumatol 1987; 5(Suppl I): S105-SlO7. Van Tieeelen R. Sacroiliitis: difficulties in the rad%graphic diagnosis: advantage of CI? Preliminary report. J Belge Rad 1987; 70: 14. Wilbur AC, Langer BG, Spigos DG. Diagnosis of sacroiliac joint infection in pregnancy by magnetic resonance imaging case report. Magn Res h a g 1988; 6: 341-343.
13. Dalinka MK, Zlatkin MB, Chao P et a/. The use of magnetic resonance imaging in the evaluation of bone and soft tissue tumors. Rad Clin North Am 1990; 28: 46 1 -467. 14. Gold RI. Seeger LL, Bassett LW ef ul. An integrated approach to the evaluation of metastatic bone disease. Rad Clin North Am 1990; 28: 471479. 15. Sundaram M, McLeod RA. MR imaging of tumor and tumorlike lesions of bone’ and soft tissue. AJR 1990; 155: 817-824. 16. Bloem JL, Taminiau AH, Eulderink R er al. Radiologic staging of primary bone sarcoma: MR imaging, scintigraphy and CT correlated with pathologic examination. Radiology -. 1988; 169: 805-810. 17. Wetzel LH, Levin E, ~~~~h~ MD. A comparison of MR imaging and CT in the evaluation of musculoskeletal masses. Radiographics 1987; 7: - 851-862. 18, Sundaram M, McGuire MH, Computed tomography or magnetic resonance for evaluating the solitarv tumor or tumorlike lesion 07 bone? Skklet Rad 1988; 17: 393-401.
AusfrakusianRudiologv. Vol. 36. No. 4. November, I992
