Skeletal Radiol (1992) 21 : 330-334
Skeletal Radiology
Case report 739 Elizabeth Schultz, M.D. 1, Ira Richterman, M.D. 2, and Howard D. Dorfman, M.D. 3 Departments of 1 Diagnostic Radiology and 3 Orthopaedic Surgery, Albert Einstein College of Medicine at Montefiore Medical Center, Bronx, New York, USA 2 Department of Orthopaedics, Albert Einstein Medical Center, Philadelphia, Pennsylvania, USA
Imaging studies Fig. 1 A, B. Frontal and lateral views of the left knee demonstrate increased softtissue density in the suprapatellar pouch and a marginal erosion along the medial aspect of the tibial plateau Fig. 2A, B. Sagittal T1- and T2-weighted magnetic resonance images of the left knee demonstrate a lobulated, inhomogeneous, synovial mass occupying the retropatellar and suprapatellar aspects of the joint. In addition to synovial fluid, foci of decreased and absent signal are seen on both images
Address reprint requests to: Elizabeth Schultz, M.D., Department of Radiology, Montefiore Medical Center, 111 East 210th Street, Bronx, N.Y. 10467-2490, USA
9 1992 International Skeletal Society
E. Schultzet al. : Case report 739 Clinical information
A 46-year-old Vietnamese man presented with a history of pain and swelling of the left knee for 5 months. The issue of prior trauma to the knee was uncertain. The patient was otherwise in good health. Upon questioning, no significant past medical or surgical history was elicited. Physical examination revealed swelling of the knee, tenderness, particularly along the medial aspect of the joint, and decreased range of motion secondary to pain. No erythema or other lesions of the skin was present. The remainder of the physical examination was unremarkable.
331 Plain radiographs of the knee were obtained, demonstrating an effusion and a small lucency along the medial aspect of the tibial plateau (Fig. 1). Aspiration of fluid from the knee was performed. Laboratory examinations of the synovial fluid, including cultures, were negative. The patient then underwent magnetic resonance imaging (MRI) which revealed a large synovial effusion with inhomogeneous signal on both TIand T2-weighted images (Fig. 2). The patient failed to keep his appointments with the clinic until 8 months later, when persistent pain and swelling of the knee prompted his return.
Repeat aspiration of the knee was performed, and 50 cc of bloody fluid were obtained and sent for laboratory examination. In addition, the patient underwent arthroscopy which demonstrated diffuse hypertrophic synovitis, loose cartilaginous fragments, an osteochondral defect in the medial femoral condyle, and grade II chondromalacia. A synovectomy of the suprapatellar pouch was performed, as well as debridement of loose cartilaginous fragments from the medial compartment of the knee joint. Samples of synovial tissue were sent for further pathological examination.
332
Diagnosis: Tuberculous arthritis of knee The differential diagnosis included pigmented villonodular synovitis (PVS), hemarthrosis, hemophilia, hemangioma o f synovium, synovial chondromatosis, rheumatoid arthritis, gout, and synovial effusion with intra articular loose bodies. Pathological examination of the submitted synovial tissue revealed granulomatous inflammation with tuberculoid granulomas showing central foci of caseation necrosis. Langhans' giant cells were prominent among the epithelioid histiocytes of these granulomas (Fig. 3). Acid-fast bacilli, sparse in number but consistent morphologically with Mycobac-
E. Schultz et al.: Case report 739
teriurn tuberculosis, were present in the granulation tissue. Radiographic examination of the chest demonstrated fibronodular densities in the right upper lobe, consistent with a tuberculous infiltrate of uncertain activity. Discussion The spine and the large and mediumsized joints (particularly the hip and knee) are the most commonly affected areas of the skeleton. Generally, a single joint is affected. Unlike the behavior of pyogenic infection where the epiphyseal plate acts as a barrier to spread of infection from the metaphysis to the subchondral
bone, a tuberculous joint may become secondarily infected from a tuberculous focus located in a nearby metaphysis. More commonly, however, the joint is infected primarily, with the site of infection originating within the synovium, the subchondral bone, or both [5]. Hematogenous pathways account for spread of the disease in the skeletal system. While it is generally assumed that a primary pulmonary focus of tuberculosis occurs initially, more than 50% of patients who have skeletal tuberculosis (TB) will not demonstrate radiological evidence of either active or prior disease on examination of the chest. Juxtaarticular osteoporosis and swelling of the soft tissues are the
Pathological study and follow-up
Fig. 3. Epithelioid granulomas with Langhans' giant cells in tuberculous granulation tissue from the synovium of the knee are noted. Foci of central necrosis are present in some of the granulomas, and acid-fast bacilli were demonstrated in sections stained by the Ziehl-Neelsen method (H&E, original magnification x 150) Fig. 4A, B. One year after the initial imaging studies, osteoporosis, marginal erosion, and relative sparing of the cartilage (comprising Phemister's triad) are demonstrated
E. Schultz et al. : Case report 739 earliest radiological changes observed when involvement of a joint occurs. Advanced synovial disease can occur with only minimal osseous findings. Destruction of the articular cartilage characteristically progresses slowly. Erosions of the articular bone begin at the peripheral margins. Thus, the triad of Phemister, comprising osteoporosis, peripheral marginal erosions of the subchondral bone, and slowly progressing destruction of the cartilage is produced (Fig. 4). Fusion of a joint is uncommon; when bony ankylosis does occur in tuberculous arthritis, an additional pyogenic infection in the same joint will be responsible for osteolysis developing more often than in tuberculosis alone. Although the features observed on M R I of tuberculous spondylitis, intracranial tuberculosis, and disseminated osseous tuberculosis have been described [1, 3, 4, 6, 11], few reported cases of the characteristics on M R I of tuberculous involvement of a joint have appeared in the medical literature. A single case of tuberculous arthritis of the shoulder examined by M R I was reported in the Japanese literature [10], and a patient with tuberculous trochanteritis who underwent M R I was described in the French literature [2]. To the best of our knowledge, the M R I features of tuberculous involvement of the knee have not been previously reported. The findings noted on M R I of our patient indicate a synovial process presenting mainly as an effusion. The loci of low and absent signal are most likely due to bleeding with deposition of hemosiderin and loose cartilaginous fragments. The most commonly encountered synovial process demonstrating features on M R I similar to those depicted in our case is pigmented villonodular synovitis (PVS). Steinbach et al. [8] reported a series of eleven patients with PVS of the knee. The most consistent findings observed on M R I were synovial hypertrophy and deposition of hemosiderin. Interestingly, involvement of the synovium located immediately posterior to the cruciate ligaments was present in each of the 11 patients. Synovial effusions were evident in most of the cases. The case of PVS demonstrated
333 inhomogenous low to intermediate signal on Tl-weighted images and low signal on T2-weighted images, interspersed with areas of bright signal when an effusion coexisted. Due to the magnetic characteristics of hemosiderin, a greater degree of contrast between the deposits of hemosiderin and the surrounding synovial fluid can be achieved by employing gradient echo technique. With this the signal produced by hemosiderin becomes even darker, while that from the adjacent fluid is bright. Absence of both thinning of the cartilage and osseous erosions is also characteristic of PVS when the osseous structures of the knee are affected. These features have been attributed to the laxity of the capsule of the joint. However, when erosions do occur, they are generally more centrally located within the joint than are the classical marginal erosions of tuberculosis. Hemophilia and chronic trauma also demonstrate synovial thickening, effusion, and hemosiderin-laden masses on MRI. The presence of cartilaginous and subchondral erosive changes, as well as thinning of the cartilage, helps to establish the diagnosis of hemophilia. Bony erosions occurring in instances of hemophilia are located centrally within the joint, as they are in PVS. Areas of low signal are seen on both T1- and T2weighted images, corresponding to deposits of hemosiderin, with bright signal demonstrable on T2-weighted studies, reflecting synovial fluid [12]. Synovial osteochondromatosis (SO) may manifest a variable appearance on MRI, ranging from void of signals to low, intermediate, or even high signal on TI. The absent signal is due to ossification and calcification, which could be mistaken for hemosiderin. Less densely calcified material produces a low to intermediate signal, while the presence of fat within synovial osteochondromas yields a bright signal [71. Based on their experience with M R I of the synovium, Sundaram et al. [9] observed that calcium is more readily observed when it is located peripherally around a lesion (as occurs with SO) than when it is located centrally within a lesion. While the spectrum of M R findings seen with SO can simu-
late other synovial diseases, the bony and calcified deposits are distinguished by their discrete, well-circumscribed appearance. Furthermore, radiographic (plain film) examination of the affected joint generally demonstrates typical calcifications. Additional synovial processes that may manifest an appearance similar to SO on M R I include rheumatoid arthritis, gout, synovial inflammation with intraarticular loose bodies, and septic arthritis with inflammatory debris. The mixed, inhomogeneous signal seen with rheumatoid arthritis is believed to be caused by inflammation, fluid, and pannus. Gouty tophi situated within an effusion have been described as areas of low or absent signal surrounded by fluid. Intraarticular loose bodies with coexisting synovial effusion may give rise to an appearance identical to SO, as can solid inflammatory debris associated with increased synovial fluid [71. To the best of our knowledge, the MRI features of synovial hemangioma have not been described in the medical literature. Since synovial hemangioma is also capable of inducing a hemosiderotic synovitis, we would anticipate its appearance on M R to be similar to other synovial processes discussed in the foregoing. In summary, the appearance on MRI of tuberculous arthritis of the knee is described. To the best of our knowledge, these findings have not been previously reported. The synovial process that most closely resembles the features observed in our patient is PVS. Other entities that can give rise to a similar appearance on M R I include hemophilia as well as other causes of hemarthrosis, synovial osteochondromatosis, rheumatoid arthritis, gout, posttraumatic loose bodies with coexisting synovial effusion, and septic arthritis.
References 1. Bell GR, Stearns KL, Bonutti PM, et al. (1990) MRI diagnosis of tuberculous vertebral osteomyelitis. Spine t5 (6):462 2. Chen J, Dufour M, Roux H (1989) Int+r~t de l'imagerie par resonance magnetique dans l'exploration des formations
334 abced6es profondes. Apropos de un cas de trochanterite tuberculeuse. Rev Rhum Mal Osteoartic 56 (8-9):625 3. Demaerel P, Wilms G, Marchal G (1990) MRI findings in tuberculous meningo-encephalitis. ROFO 152 (4): 384 4. Gupta RK, Jena A, Sharma A (1989) Sellar abscess associated with tuberculous osteomyelitis of the skull: MR findings. AJNR 10 (2):448 5. Murray RO, Jacobson HG, Stoker DJ (1990) The radiology of skeletal disorders, 3rd edn. Churchill Livingstone, Edinburgh
E. Schultz et al.: Case report 739 6. Quinn SF, Murray W, Prochaska J, et al. (1987) MRI appearance of disseminated osseous tuberculosis. Magn Reson Imagig 5 (6):4493 7. Sanchez RB, Quinn SF (1989) MRI of inflammatory synovial processes. Magn Reson Imagin 7 (5) : 529 8. Steinbach LS, Neumann CH, Stoller DW, et al. (1989) MRI of the knee in diffuse pigmented villonodular synovitis. Clin Imagin 13 (4): 305 9. Sundaram M, McGuire MH, Fletcher J, et al. (1986) Magnetic resonance imaging of lesions of synovial origin Skel. Radiol 15 : 110
10. Toyoda M, Harasawa A, Kohno A, et al. (1990) A case of tuberculous arthritis of shoulder. Rinsho-Hoshasen 35 (11):1455 1l. Vaylet F, deMuizon H, L'Her P, et al. (1989) La tuberculose osseuse multifocale. A propos d'une observation exceptionnellc. Rev Pneumol Clin 45 (2):81 12. Yulish BS, Lieberman JM, Strandjord SE, et al. (1987) Hemophilic arthropathy : assessment with MR imaging. Radiology 164: 759
Skeletal Radiology
Case report 739 Elizabeth Schultz, M.D. 1, Ira Richterman, M.D. 2, and Howard D. Dorfman, M.D. 3 Departments of 1 Diagnostic Radiology and 3 Orthopaedic Surgery, Albert Einstein College of Medicine at Montefiore Medical Center, Bronx, New York, USA 2 Department of Orthopaedics, Albert Einstein Medical Center, Philadelphia, Pennsylvania, USA
Imaging studies Fig. 1 A, B. Frontal and lateral views of the left knee demonstrate increased softtissue density in the suprapatellar pouch and a marginal erosion along the medial aspect of the tibial plateau Fig. 2A, B. Sagittal T1- and T2-weighted magnetic resonance images of the left knee demonstrate a lobulated, inhomogeneous, synovial mass occupying the retropatellar and suprapatellar aspects of the joint. In addition to synovial fluid, foci of decreased and absent signal are seen on both images
Address reprint requests to: Elizabeth Schultz, M.D., Department of Radiology, Montefiore Medical Center, 111 East 210th Street, Bronx, N.Y. 10467-2490, USA
9 1992 International Skeletal Society
E. Schultzet al. : Case report 739 Clinical information
A 46-year-old Vietnamese man presented with a history of pain and swelling of the left knee for 5 months. The issue of prior trauma to the knee was uncertain. The patient was otherwise in good health. Upon questioning, no significant past medical or surgical history was elicited. Physical examination revealed swelling of the knee, tenderness, particularly along the medial aspect of the joint, and decreased range of motion secondary to pain. No erythema or other lesions of the skin was present. The remainder of the physical examination was unremarkable.
331 Plain radiographs of the knee were obtained, demonstrating an effusion and a small lucency along the medial aspect of the tibial plateau (Fig. 1). Aspiration of fluid from the knee was performed. Laboratory examinations of the synovial fluid, including cultures, were negative. The patient then underwent magnetic resonance imaging (MRI) which revealed a large synovial effusion with inhomogeneous signal on both TIand T2-weighted images (Fig. 2). The patient failed to keep his appointments with the clinic until 8 months later, when persistent pain and swelling of the knee prompted his return.
Repeat aspiration of the knee was performed, and 50 cc of bloody fluid were obtained and sent for laboratory examination. In addition, the patient underwent arthroscopy which demonstrated diffuse hypertrophic synovitis, loose cartilaginous fragments, an osteochondral defect in the medial femoral condyle, and grade II chondromalacia. A synovectomy of the suprapatellar pouch was performed, as well as debridement of loose cartilaginous fragments from the medial compartment of the knee joint. Samples of synovial tissue were sent for further pathological examination.
332
Diagnosis: Tuberculous arthritis of knee The differential diagnosis included pigmented villonodular synovitis (PVS), hemarthrosis, hemophilia, hemangioma o f synovium, synovial chondromatosis, rheumatoid arthritis, gout, and synovial effusion with intra articular loose bodies. Pathological examination of the submitted synovial tissue revealed granulomatous inflammation with tuberculoid granulomas showing central foci of caseation necrosis. Langhans' giant cells were prominent among the epithelioid histiocytes of these granulomas (Fig. 3). Acid-fast bacilli, sparse in number but consistent morphologically with Mycobac-
E. Schultz et al.: Case report 739
teriurn tuberculosis, were present in the granulation tissue. Radiographic examination of the chest demonstrated fibronodular densities in the right upper lobe, consistent with a tuberculous infiltrate of uncertain activity. Discussion The spine and the large and mediumsized joints (particularly the hip and knee) are the most commonly affected areas of the skeleton. Generally, a single joint is affected. Unlike the behavior of pyogenic infection where the epiphyseal plate acts as a barrier to spread of infection from the metaphysis to the subchondral
bone, a tuberculous joint may become secondarily infected from a tuberculous focus located in a nearby metaphysis. More commonly, however, the joint is infected primarily, with the site of infection originating within the synovium, the subchondral bone, or both [5]. Hematogenous pathways account for spread of the disease in the skeletal system. While it is generally assumed that a primary pulmonary focus of tuberculosis occurs initially, more than 50% of patients who have skeletal tuberculosis (TB) will not demonstrate radiological evidence of either active or prior disease on examination of the chest. Juxtaarticular osteoporosis and swelling of the soft tissues are the
Pathological study and follow-up
Fig. 3. Epithelioid granulomas with Langhans' giant cells in tuberculous granulation tissue from the synovium of the knee are noted. Foci of central necrosis are present in some of the granulomas, and acid-fast bacilli were demonstrated in sections stained by the Ziehl-Neelsen method (H&E, original magnification x 150) Fig. 4A, B. One year after the initial imaging studies, osteoporosis, marginal erosion, and relative sparing of the cartilage (comprising Phemister's triad) are demonstrated
E. Schultz et al. : Case report 739 earliest radiological changes observed when involvement of a joint occurs. Advanced synovial disease can occur with only minimal osseous findings. Destruction of the articular cartilage characteristically progresses slowly. Erosions of the articular bone begin at the peripheral margins. Thus, the triad of Phemister, comprising osteoporosis, peripheral marginal erosions of the subchondral bone, and slowly progressing destruction of the cartilage is produced (Fig. 4). Fusion of a joint is uncommon; when bony ankylosis does occur in tuberculous arthritis, an additional pyogenic infection in the same joint will be responsible for osteolysis developing more often than in tuberculosis alone. Although the features observed on M R I of tuberculous spondylitis, intracranial tuberculosis, and disseminated osseous tuberculosis have been described [1, 3, 4, 6, 11], few reported cases of the characteristics on M R I of tuberculous involvement of a joint have appeared in the medical literature. A single case of tuberculous arthritis of the shoulder examined by M R I was reported in the Japanese literature [10], and a patient with tuberculous trochanteritis who underwent M R I was described in the French literature [2]. To the best of our knowledge, the M R I features of tuberculous involvement of the knee have not been previously reported. The findings noted on M R I of our patient indicate a synovial process presenting mainly as an effusion. The loci of low and absent signal are most likely due to bleeding with deposition of hemosiderin and loose cartilaginous fragments. The most commonly encountered synovial process demonstrating features on M R I similar to those depicted in our case is pigmented villonodular synovitis (PVS). Steinbach et al. [8] reported a series of eleven patients with PVS of the knee. The most consistent findings observed on M R I were synovial hypertrophy and deposition of hemosiderin. Interestingly, involvement of the synovium located immediately posterior to the cruciate ligaments was present in each of the 11 patients. Synovial effusions were evident in most of the cases. The case of PVS demonstrated
333 inhomogenous low to intermediate signal on Tl-weighted images and low signal on T2-weighted images, interspersed with areas of bright signal when an effusion coexisted. Due to the magnetic characteristics of hemosiderin, a greater degree of contrast between the deposits of hemosiderin and the surrounding synovial fluid can be achieved by employing gradient echo technique. With this the signal produced by hemosiderin becomes even darker, while that from the adjacent fluid is bright. Absence of both thinning of the cartilage and osseous erosions is also characteristic of PVS when the osseous structures of the knee are affected. These features have been attributed to the laxity of the capsule of the joint. However, when erosions do occur, they are generally more centrally located within the joint than are the classical marginal erosions of tuberculosis. Hemophilia and chronic trauma also demonstrate synovial thickening, effusion, and hemosiderin-laden masses on MRI. The presence of cartilaginous and subchondral erosive changes, as well as thinning of the cartilage, helps to establish the diagnosis of hemophilia. Bony erosions occurring in instances of hemophilia are located centrally within the joint, as they are in PVS. Areas of low signal are seen on both T1- and T2weighted images, corresponding to deposits of hemosiderin, with bright signal demonstrable on T2-weighted studies, reflecting synovial fluid [12]. Synovial osteochondromatosis (SO) may manifest a variable appearance on MRI, ranging from void of signals to low, intermediate, or even high signal on TI. The absent signal is due to ossification and calcification, which could be mistaken for hemosiderin. Less densely calcified material produces a low to intermediate signal, while the presence of fat within synovial osteochondromas yields a bright signal [71. Based on their experience with M R I of the synovium, Sundaram et al. [9] observed that calcium is more readily observed when it is located peripherally around a lesion (as occurs with SO) than when it is located centrally within a lesion. While the spectrum of M R findings seen with SO can simu-
late other synovial diseases, the bony and calcified deposits are distinguished by their discrete, well-circumscribed appearance. Furthermore, radiographic (plain film) examination of the affected joint generally demonstrates typical calcifications. Additional synovial processes that may manifest an appearance similar to SO on M R I include rheumatoid arthritis, gout, synovial inflammation with intraarticular loose bodies, and septic arthritis with inflammatory debris. The mixed, inhomogeneous signal seen with rheumatoid arthritis is believed to be caused by inflammation, fluid, and pannus. Gouty tophi situated within an effusion have been described as areas of low or absent signal surrounded by fluid. Intraarticular loose bodies with coexisting synovial effusion may give rise to an appearance identical to SO, as can solid inflammatory debris associated with increased synovial fluid [71. To the best of our knowledge, the MRI features of synovial hemangioma have not been described in the medical literature. Since synovial hemangioma is also capable of inducing a hemosiderotic synovitis, we would anticipate its appearance on M R to be similar to other synovial processes discussed in the foregoing. In summary, the appearance on MRI of tuberculous arthritis of the knee is described. To the best of our knowledge, these findings have not been previously reported. The synovial process that most closely resembles the features observed in our patient is PVS. Other entities that can give rise to a similar appearance on M R I include hemophilia as well as other causes of hemarthrosis, synovial osteochondromatosis, rheumatoid arthritis, gout, posttraumatic loose bodies with coexisting synovial effusion, and septic arthritis.
References 1. Bell GR, Stearns KL, Bonutti PM, et al. (1990) MRI diagnosis of tuberculous vertebral osteomyelitis. Spine t5 (6):462 2. Chen J, Dufour M, Roux H (1989) Int+r~t de l'imagerie par resonance magnetique dans l'exploration des formations
334 abced6es profondes. Apropos de un cas de trochanterite tuberculeuse. Rev Rhum Mal Osteoartic 56 (8-9):625 3. Demaerel P, Wilms G, Marchal G (1990) MRI findings in tuberculous meningo-encephalitis. ROFO 152 (4): 384 4. Gupta RK, Jena A, Sharma A (1989) Sellar abscess associated with tuberculous osteomyelitis of the skull: MR findings. AJNR 10 (2):448 5. Murray RO, Jacobson HG, Stoker DJ (1990) The radiology of skeletal disorders, 3rd edn. Churchill Livingstone, Edinburgh
E. Schultz et al.: Case report 739 6. Quinn SF, Murray W, Prochaska J, et al. (1987) MRI appearance of disseminated osseous tuberculosis. Magn Reson Imagig 5 (6):4493 7. Sanchez RB, Quinn SF (1989) MRI of inflammatory synovial processes. Magn Reson Imagin 7 (5) : 529 8. Steinbach LS, Neumann CH, Stoller DW, et al. (1989) MRI of the knee in diffuse pigmented villonodular synovitis. Clin Imagin 13 (4): 305 9. Sundaram M, McGuire MH, Fletcher J, et al. (1986) Magnetic resonance imaging of lesions of synovial origin Skel. Radiol 15 : 110
10. Toyoda M, Harasawa A, Kohno A, et al. (1990) A case of tuberculous arthritis of shoulder. Rinsho-Hoshasen 35 (11):1455 1l. Vaylet F, deMuizon H, L'Her P, et al. (1989) La tuberculose osseuse multifocale. A propos d'une observation exceptionnellc. Rev Pneumol Clin 45 (2):81 12. Yulish BS, Lieberman JM, Strandjord SE, et al. (1987) Hemophilic arthropathy : assessment with MR imaging. Radiology 164: 759
