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Arthroscopic Treatment for Gouty Tophi Mimicking an Intra-articular Synovial Tumor of the Knee
Case Report
Arthroscopic Treatment for Gouty Tophi Mimicking an Intra-articular Synovial Tumor of the Knee Tzung-Je Li, M.D., Ko-Huang Lue, M.D., Zong-I Lin, M.D., Ph.D., and Ko-Hsiu Lu, M.D., Ph.D.
Abstract: Tophi deposition is a well-recognized complication of chronic gout, but usually lacks obvious symptoms. Magnetic resonance imaging (MRI) findings may allow a relatively specific diagnosis to be rendered. In this study, we report an unusual case of gouty tophi presenting as an intra-articular synovial tumor of the knee, blocking the range of motion. We also describe its MRI appearance, which was compatible with the clinical suspicion. After arthroscopic excision of the “tumor,” the patient was symptom free. Key Words: Tophus—Synovial tumor—Magnetic resonance imaging—Arthroscopy—Knee.
G
out is a disease of purine metabolism or renal excretion of uric acid and is considered to have 4 different phases characterized by asymptomatic hyperuricemia, recurrent attacks of acute arthritis, intercritical gout, and chronic tophaceous gout. Monosodium urate deposition with punch-out bony erosions is a well-recognized complication of chronic tophaceous gout, but usually lacks obvious symptoms. When gouty tophi present as soft-tissue masses in the absence of articular disease, the tophi may be confused with a neoplastic process. Based on magnetic resonance imaging (MRI) appearance, the differential diagnosis also includes pigmented villonodu-
From the Department of Orthopaedic Surgery, Chung Shan Medical University Hospital (T-J.L. Z-I.L., K-H.Lu); and the School of Medicine (K-H.Lue, Z-I.L., K-H.Lu), Chung Shan Medical University, Taichung, Taiwan, Republic of China. Address correspondence and reprint requests to Ko-Hsiu Lu, M.D., Ph.D., Department of Orthopaedic Surgery, Chung Shan Medical University Hospital, No. 110, Sec 1 Chien-Kuo N. Road, Taichung 402, Taiwan, Republic of China. E-mail: cshy307@ csh.org.tw © 2006 by the Arthroscopy Association of North America Cite this article as: Li T-J, Lue K-H, Lin Z-I, Lu K-H. Arthroscopic treatment for gouty tophi mimicking an intra-articular synovial tumor of the knee. Arthroscopy 2006;22:910.e1-910.e3 [doi:10.1016/j.arthro.2005.06.031]. 0749-8063/06/2208-x511$32.00/0 doi:10.1016/j.arthro.2005.06.031
lar synovitis (PVNS), chronic rheumatoid arthritis, chronic infectious arthritis, and amyloidosis.1 The constellation of clinical and MRI findings may allow a relatively specific diagnosis to be rendered. To our knowledge, we herein first report a case of arthroscopic treatment for gouty tophi in which clinical suspicion and its MRI findings were compatible with an intra-articular synovial tumor of the knee.
CASE REPORT A 53-year-old man presented to our clinic with persistent right posterolateral knee pain blocking full flexion of the knee of 8 years’ duration. Conservative treatment at many hospitals had failed, so the patient had ignored his condition. During the past year, the posterolateral knee pain did not worsen, but anterior knee pain with an irritating tumor-like sensation behind the patella had developed and aggravated the range of motion, especially during walking. The patient did not recall any knee trauma that predated the initial knee symptoms. In addition, he had a 6-year history of gout without subcutaneous tophi. Physical examination of the right knee showed some effusions and tenderness along the anterolateral aspect of the joint, without any herniating mass. The patellar grind test and gliding test were positive. The
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 8 (August), 2006: pp 910.e1-910.e3
910.e1
910.e2
T-J. LI ET AL.
FIGURE 1. MRIs show 2 masses (arrow) interposing (A) in the superolateral patellofemoral joint and (B-E) in the lateral gutter, which caused erosion of the lateral femoral condyle. The 2 masses showed low to inhomogeneously intermediate signal intensity on both T1- and T2-weighted images with heterogeneous peripheral enhancement (arrowhead).
patient’s extension and flexion range of motion were limited to between 5° and 120°. Other tests were negative (i.e., McMurray and ligament stress tests). Laboratory test results were within normal limits except for a high uric acid concentration in the serum (10.6 mg/dL). The 10 mL of clear joint effusions contained 225/mL leukocytes with 3% neutrophils. Radiographs did not show any abnormalities or calcifications to provide diagnostic assistance except for a doubtful bony erosion of the lateral femoral condyle near the origin of the popliteal tendon. An MRI was ordered because we suspected an intraarticular tumor. At the time of the MRI examination, there was an acute attack of gout, so MRI revealed a lot of joint effusions and ring enhancement of the synovium after administration of gadolinium (Fig 1). It also showed a multifocal irregular synovial tumor involving the anterior cruciate ligament and the superior area of the lateral retinaculum; particularly, 2 large masses interposing in the superolateral patellofemoral joint and in the lateral gutter. Subsequent arthrocentesis revealed 66 mL of inflammatory effusions (3,000/mL leukocytes with 91% neutrophils)
that were compatible with an acute gout attack, not hemorrhagic effusions.2 According to the findings, we diagnosed a multifocal synovial neoplasm, without ruling out other entities such as gouty tophi and chronic inflammatory or infectious arthritis. With the tentative diagnosis of an intra-articular synovial tumor combined with gout, arthroscopy was performed after subsidence of the inflammation. At arthroscopy, it was found that almost all synovia and articular surfaces of the knee were tapestried with urate crystals and that multiple tophi had infiltrated the anterior segment of the medial meniscus, the anterior cruciate ligament, and the superior area of the lateral retinaculum, particularly 2 large ones showing the appearance of tumors in the lateral gutter and over the anterosuperior margin of the lateral femoral condyle, respectively (Fig 2). The surface of the tophi was covered with synovium with engorged vessels. No meniscal or ligamentous pathology could be seen. The articular cartilage, the anterior cruciate ligament, the medial meniscus, and synovia that were thickened and interspersed with chalky flecks on the surface were debrided and the tophi were excised arthroscopically. Histologic examination revealed amorphous uric acid deposits surrounded by fibrous tissue and rimmed by both mononuclear histiocytes and giant cells, consistent with gouty tophi. Intensive isometric quadriceps exercises were encouraged immediately and early full weight-bearing was allowed postoperatively. The patient was very satisfied with the results and had
FIGURE 2. Intraoperative arthroscopic views of the tophi with chalky white deposits, covered with synovium with engorged vessels, (A) one in the lateral gutter (arrow) and (B) the other over the anterosuperior margin of the lateral femoral condyle (arrowhead). (C, D) The tophi were excised and the patellar surface was debrided.
ARTHROSCOPY FOR TOPHI MIMICKING KNEE TUMOR full active and passive range of motion, without pain, in weeks. DISCUSSION Gout has been termed “the great mimic” for its ability to resemble multiple conditions. Similarly, intra-articular tophi of the knee can cause mechanical symptoms which are an important but rare cause of persistent walking disability in persons with gout.3 Also, a tophus occasionally mimics an infectious or neoplastic process, and an MRI may be obtained under these circumstances. In this case, the focus had been on the clinical picture and the MRI appearance, which resulted in a misdiagnosis of an intra-articular synovial tumor and, as a result, a proper diagnosis had been delayed for 8 years since the initial knee symptoms. In general, the features of gout on plain-film radiographs are negative in early and even chronic gout patients with intra-articular deposits and bony erosions. In addition to computed tomography,4,5 an MRI may be helpful in establishing the diagnosis and is the current image of choice, although it is expensive and still remains a diagnostic difficulty.4,6,7 The MRI appearance of tophi usually is of nonspecific low to intermediate signal intensity on both TI- and T2weighted images and a variable enhancement pattern. The enhancement is likely a reflection of the increased hypervascularity of the affected synovium and hypervascular granulation tissue. In the presence of associated inflammation, MRI of tophi may display high signal intensity, and the proliferative synovitis that characterizes all synovial inflammatory processes is also elicited, as we saw in our patient. Even though the patient had a 6-year history of gout with a high serum urate level, our first clinical diagnosis was not gouty tophi, for the following reasons: (1) intra-articular tophi lack clinically obvious presentations; (2) patients usually have had gout for 10 to 12 years before these lesions become visible radiographically or on physical examination8; (3) calcification within tophi is reported to be the diagnostic characteristic, although it is rare3,4; and (4) MRI findings cannot be considered specific to tophi, especially a nonspecific enhancement.4,6,7 As previously reported, and as in the case of our patient,1 MRI of PVNS may not show the typical
910.e3
presentation, such as a heterogeneous soft-tissue mass with low signal intensity on T1- and T2-weighted images corresponding to the hemosiderin deposition. Nevertheless, joint aspiration for PVNS typically should yield hemorrhagic or xanthochromic/serosanguinous (brown, murky) fluid, unlike this patient who had nonhemorrhagic effusions. Furthermore, the heterogeneous peripheral enhancement, inflammatory effusions, and multifocal masses in the joint may lead to the suspicion of an infectious and neoplastic process. However, both effusions might be diagnosed as noninfectious arthritis rather than infectious arthritis in a native knee.2 Gouty tophi can be easily observed during arthroscopy, but they are usually asymptomatic and do not need surgical intervention. Just like the patient discussed in this report, arthroscopy can be indicated for persistent mechanical symptoms in an intercritical phase, which not only provides the definite diagnosis but also treats the long-term problems adequately. Acknowledgment: The authors thank Chung-Hung Tsai, M.D., Department of Pathology, Chung Shan Medical University, for his advice regarding histology; and NieuTsu Han, M.D., Department of Radiology, Chung Shan Medical University, for his advice regarding MRIs.
REFERENCES 1. Lu KH. Subcutaneous pigmented villonodular synovitis caused by portal contamination during knee arthroscopy and open synovectomy. Arthroscopy 2004;20:e9-e13 (available at www. arthroscopyjournal.org). 2. Chu SC, Yang SF, Lue KH, Hsieh YS, Lin ZI, Lu KH. Clinical significance of gelatinases in septic arthritis of native and replaced knee. Clin Orthop 2004;427:179-183. 3. Melloni P, Valls R, Yuguero M, Saez A. An unusual case of tophaceous gout involving the anterior cruciate ligament. Arthroscopy 2004;20:e117-e121 (available at www.arthroscopy journal.org). 4. Chen CK, Yeh LR, Pan HB, et al. Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients. Skeletal Radiol 1999;28:75-80. 5. Gerster JC, Landry M, Dufresne L, Meuwly JY. Imaging of tophaceous gout: Computed tomography provides specific images compared with magnetic resonance imaging and ultrasonography. Ann Rheum Dis 2002;61:52-54. 6. Yu JS, Chung C, Recht M, Dailiana T, Jurdi R. MR imaging of tophaceous gout. AJR Am J Roentgenol 1997;168:523-527. 7. Gentili A. Advanced imaging of gout. Semin Musculoskelet Radiol 2003;7:165-174. 8. Resnick D, Niwayama G. Gouty arthritis. In: Resnick D, Niwayama G, eds. Diagnosis of bone and joint disorders. Ed 2. Philadelphia: WB Saunders, 1988;1618-1671.
Arthroscopic Treatment for Gouty Tophi Mimicking an Intra-articular Synovial Tumor of the Knee Tzung-Je Li, M.D., Ko-Huang Lue, M.D., Zong-I Lin, M.D., Ph.D., and Ko-Hsiu Lu, M.D., Ph.D.
Abstract: Tophi deposition is a well-recognized complication of chronic gout, but usually lacks obvious symptoms. Magnetic resonance imaging (MRI) findings may allow a relatively specific diagnosis to be rendered. In this study, we report an unusual case of gouty tophi presenting as an intra-articular synovial tumor of the knee, blocking the range of motion. We also describe its MRI appearance, which was compatible with the clinical suspicion. After arthroscopic excision of the “tumor,” the patient was symptom free. Key Words: Tophus—Synovial tumor—Magnetic resonance imaging—Arthroscopy—Knee.
G
out is a disease of purine metabolism or renal excretion of uric acid and is considered to have 4 different phases characterized by asymptomatic hyperuricemia, recurrent attacks of acute arthritis, intercritical gout, and chronic tophaceous gout. Monosodium urate deposition with punch-out bony erosions is a well-recognized complication of chronic tophaceous gout, but usually lacks obvious symptoms. When gouty tophi present as soft-tissue masses in the absence of articular disease, the tophi may be confused with a neoplastic process. Based on magnetic resonance imaging (MRI) appearance, the differential diagnosis also includes pigmented villonodu-
From the Department of Orthopaedic Surgery, Chung Shan Medical University Hospital (T-J.L. Z-I.L., K-H.Lu); and the School of Medicine (K-H.Lue, Z-I.L., K-H.Lu), Chung Shan Medical University, Taichung, Taiwan, Republic of China. Address correspondence and reprint requests to Ko-Hsiu Lu, M.D., Ph.D., Department of Orthopaedic Surgery, Chung Shan Medical University Hospital, No. 110, Sec 1 Chien-Kuo N. Road, Taichung 402, Taiwan, Republic of China. E-mail: cshy307@ csh.org.tw © 2006 by the Arthroscopy Association of North America Cite this article as: Li T-J, Lue K-H, Lin Z-I, Lu K-H. Arthroscopic treatment for gouty tophi mimicking an intra-articular synovial tumor of the knee. Arthroscopy 2006;22:910.e1-910.e3 [doi:10.1016/j.arthro.2005.06.031]. 0749-8063/06/2208-x511$32.00/0 doi:10.1016/j.arthro.2005.06.031
lar synovitis (PVNS), chronic rheumatoid arthritis, chronic infectious arthritis, and amyloidosis.1 The constellation of clinical and MRI findings may allow a relatively specific diagnosis to be rendered. To our knowledge, we herein first report a case of arthroscopic treatment for gouty tophi in which clinical suspicion and its MRI findings were compatible with an intra-articular synovial tumor of the knee.
CASE REPORT A 53-year-old man presented to our clinic with persistent right posterolateral knee pain blocking full flexion of the knee of 8 years’ duration. Conservative treatment at many hospitals had failed, so the patient had ignored his condition. During the past year, the posterolateral knee pain did not worsen, but anterior knee pain with an irritating tumor-like sensation behind the patella had developed and aggravated the range of motion, especially during walking. The patient did not recall any knee trauma that predated the initial knee symptoms. In addition, he had a 6-year history of gout without subcutaneous tophi. Physical examination of the right knee showed some effusions and tenderness along the anterolateral aspect of the joint, without any herniating mass. The patellar grind test and gliding test were positive. The
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 8 (August), 2006: pp 910.e1-910.e3
910.e1
910.e2
T-J. LI ET AL.
FIGURE 1. MRIs show 2 masses (arrow) interposing (A) in the superolateral patellofemoral joint and (B-E) in the lateral gutter, which caused erosion of the lateral femoral condyle. The 2 masses showed low to inhomogeneously intermediate signal intensity on both T1- and T2-weighted images with heterogeneous peripheral enhancement (arrowhead).
patient’s extension and flexion range of motion were limited to between 5° and 120°. Other tests were negative (i.e., McMurray and ligament stress tests). Laboratory test results were within normal limits except for a high uric acid concentration in the serum (10.6 mg/dL). The 10 mL of clear joint effusions contained 225/mL leukocytes with 3% neutrophils. Radiographs did not show any abnormalities or calcifications to provide diagnostic assistance except for a doubtful bony erosion of the lateral femoral condyle near the origin of the popliteal tendon. An MRI was ordered because we suspected an intraarticular tumor. At the time of the MRI examination, there was an acute attack of gout, so MRI revealed a lot of joint effusions and ring enhancement of the synovium after administration of gadolinium (Fig 1). It also showed a multifocal irregular synovial tumor involving the anterior cruciate ligament and the superior area of the lateral retinaculum; particularly, 2 large masses interposing in the superolateral patellofemoral joint and in the lateral gutter. Subsequent arthrocentesis revealed 66 mL of inflammatory effusions (3,000/mL leukocytes with 91% neutrophils)
that were compatible with an acute gout attack, not hemorrhagic effusions.2 According to the findings, we diagnosed a multifocal synovial neoplasm, without ruling out other entities such as gouty tophi and chronic inflammatory or infectious arthritis. With the tentative diagnosis of an intra-articular synovial tumor combined with gout, arthroscopy was performed after subsidence of the inflammation. At arthroscopy, it was found that almost all synovia and articular surfaces of the knee were tapestried with urate crystals and that multiple tophi had infiltrated the anterior segment of the medial meniscus, the anterior cruciate ligament, and the superior area of the lateral retinaculum, particularly 2 large ones showing the appearance of tumors in the lateral gutter and over the anterosuperior margin of the lateral femoral condyle, respectively (Fig 2). The surface of the tophi was covered with synovium with engorged vessels. No meniscal or ligamentous pathology could be seen. The articular cartilage, the anterior cruciate ligament, the medial meniscus, and synovia that were thickened and interspersed with chalky flecks on the surface were debrided and the tophi were excised arthroscopically. Histologic examination revealed amorphous uric acid deposits surrounded by fibrous tissue and rimmed by both mononuclear histiocytes and giant cells, consistent with gouty tophi. Intensive isometric quadriceps exercises were encouraged immediately and early full weight-bearing was allowed postoperatively. The patient was very satisfied with the results and had
FIGURE 2. Intraoperative arthroscopic views of the tophi with chalky white deposits, covered with synovium with engorged vessels, (A) one in the lateral gutter (arrow) and (B) the other over the anterosuperior margin of the lateral femoral condyle (arrowhead). (C, D) The tophi were excised and the patellar surface was debrided.
ARTHROSCOPY FOR TOPHI MIMICKING KNEE TUMOR full active and passive range of motion, without pain, in weeks. DISCUSSION Gout has been termed “the great mimic” for its ability to resemble multiple conditions. Similarly, intra-articular tophi of the knee can cause mechanical symptoms which are an important but rare cause of persistent walking disability in persons with gout.3 Also, a tophus occasionally mimics an infectious or neoplastic process, and an MRI may be obtained under these circumstances. In this case, the focus had been on the clinical picture and the MRI appearance, which resulted in a misdiagnosis of an intra-articular synovial tumor and, as a result, a proper diagnosis had been delayed for 8 years since the initial knee symptoms. In general, the features of gout on plain-film radiographs are negative in early and even chronic gout patients with intra-articular deposits and bony erosions. In addition to computed tomography,4,5 an MRI may be helpful in establishing the diagnosis and is the current image of choice, although it is expensive and still remains a diagnostic difficulty.4,6,7 The MRI appearance of tophi usually is of nonspecific low to intermediate signal intensity on both TI- and T2weighted images and a variable enhancement pattern. The enhancement is likely a reflection of the increased hypervascularity of the affected synovium and hypervascular granulation tissue. In the presence of associated inflammation, MRI of tophi may display high signal intensity, and the proliferative synovitis that characterizes all synovial inflammatory processes is also elicited, as we saw in our patient. Even though the patient had a 6-year history of gout with a high serum urate level, our first clinical diagnosis was not gouty tophi, for the following reasons: (1) intra-articular tophi lack clinically obvious presentations; (2) patients usually have had gout for 10 to 12 years before these lesions become visible radiographically or on physical examination8; (3) calcification within tophi is reported to be the diagnostic characteristic, although it is rare3,4; and (4) MRI findings cannot be considered specific to tophi, especially a nonspecific enhancement.4,6,7 As previously reported, and as in the case of our patient,1 MRI of PVNS may not show the typical
910.e3
presentation, such as a heterogeneous soft-tissue mass with low signal intensity on T1- and T2-weighted images corresponding to the hemosiderin deposition. Nevertheless, joint aspiration for PVNS typically should yield hemorrhagic or xanthochromic/serosanguinous (brown, murky) fluid, unlike this patient who had nonhemorrhagic effusions. Furthermore, the heterogeneous peripheral enhancement, inflammatory effusions, and multifocal masses in the joint may lead to the suspicion of an infectious and neoplastic process. However, both effusions might be diagnosed as noninfectious arthritis rather than infectious arthritis in a native knee.2 Gouty tophi can be easily observed during arthroscopy, but they are usually asymptomatic and do not need surgical intervention. Just like the patient discussed in this report, arthroscopy can be indicated for persistent mechanical symptoms in an intercritical phase, which not only provides the definite diagnosis but also treats the long-term problems adequately. Acknowledgment: The authors thank Chung-Hung Tsai, M.D., Department of Pathology, Chung Shan Medical University, for his advice regarding histology; and NieuTsu Han, M.D., Department of Radiology, Chung Shan Medical University, for his advice regarding MRIs.
REFERENCES 1. Lu KH. Subcutaneous pigmented villonodular synovitis caused by portal contamination during knee arthroscopy and open synovectomy. Arthroscopy 2004;20:e9-e13 (available at www. arthroscopyjournal.org). 2. Chu SC, Yang SF, Lue KH, Hsieh YS, Lin ZI, Lu KH. Clinical significance of gelatinases in septic arthritis of native and replaced knee. Clin Orthop 2004;427:179-183. 3. Melloni P, Valls R, Yuguero M, Saez A. An unusual case of tophaceous gout involving the anterior cruciate ligament. Arthroscopy 2004;20:e117-e121 (available at www.arthroscopy journal.org). 4. Chen CK, Yeh LR, Pan HB, et al. Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients. Skeletal Radiol 1999;28:75-80. 5. Gerster JC, Landry M, Dufresne L, Meuwly JY. Imaging of tophaceous gout: Computed tomography provides specific images compared with magnetic resonance imaging and ultrasonography. Ann Rheum Dis 2002;61:52-54. 6. Yu JS, Chung C, Recht M, Dailiana T, Jurdi R. MR imaging of tophaceous gout. AJR Am J Roentgenol 1997;168:523-527. 7. Gentili A. Advanced imaging of gout. Semin Musculoskelet Radiol 2003;7:165-174. 8. Resnick D, Niwayama G. Gouty arthritis. In: Resnick D, Niwayama G, eds. Diagnosis of bone and joint disorders. Ed 2. Philadelphia: WB Saunders, 1988;1618-1671.