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A Rare Incidence of Pigmented Villonodular Synovitis of the Ankle in an Adolescent
ARTICLE IN PRESS The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery j o u r n a l h o m e p a g e : w w w. j f a s . o r g
Case Reports and Series
A Rare Incidence of Pigmented Villonodular Synovitis of the Ankle in an Adolescent David Novikov, BS 1, Meghan W. Richardson, MD 2, Corey Ho, MD 3, Elaine S. Gould, MD 4, Fazel A. Khan, MD 5 1Medical
Student, Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY Department of Radiology, Stony Brook University Hospital, Stony Brook, NY 4 Clinical Professor, Department of Radiology & Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY 5Assistant Professor, Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY 2Resident, 3Fellow,
A R T I C L E
I N F O
Level of Clinical Evidence: 4
Keywords: ankle giant cell tumor pediatrics rare tumors synovium
A B S T R A C T
Pigmented villonodular synovitis mostly affects the knee and other large joints such as the hip. Although the disease is most commonly found in adult patients aged 30 to 40 years, rare cases in children and the elderly have been reported. We present the case of an 11-year-old female who was found to have biopsy-proven pigmented villonodular synovitis in her subtalar joint in 2012. Five years after surgical excision, the patient has continued to be involved in competitive dancing and cheerleading without any pain in her ankle. Moreover, follow-up magnetic resonance imaging studies showed no evidence of recurrence. Our case report emphasizes that the disease should not be solely considered in the middle-age population but should be included in the differential diagnosis of the pediatric patient. © 2018 by the American College of Foot and Ankle Surgeons. All rights reserved.
In 1941, Jaffe et al first used the all-encompassing term “pigmented villonodular synovitis” (PVNS) to describe a number of benign, rare tumors of the synovium of the tendon, joints, and bursae (1). Since then, the terminology has changed, with the World Health Organization distinguishing between PVNS and giant cell tumor of the tendon sheath (GCTTS) in 2002, indicating that although both diseases are histologically similar, PVNS can present with diffuse involvement extending outside the joint and its surrounding tissues, in contrast to GCTTS which is a more localized disease process (2). PVNS most commonly affects the knee, followed by other large joints, including the hip. Despite its overall rare occurrence in the foot and ankle, along with GCTTS, it is the most common soft tissue tumor of the foot and ankle (3). Although the disease is most commonly found in adult patients aged 30 to 40 years, rare cases in children and the elderly have been reported (4). Furthermore, PVNS without other congenital abnormalities or sibling involvement is uncommon in children (5). We present the case of an 11-year-old female who had complained of diffuse ankle swelling and was subsequently found to have biopsy-proven PVNS in her subtalar joint. Our case report emphaFinancial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Fazel A. Khan, MD, Department of Orthopaedic Surgery, Stony Brook University Hospital, 101 Nicolls Road, Stony Brook, NY 11794. E-mail address: [email protected] (F. Khan).
sizes that the disease should not be considered limited to those in the middle-age population and should be considered in the differential diagnosis of the pediatric patient. Case Report An otherwise healthy 11-year-old female with no medical or surgical history presented to our clinic as a referral in September 2012 with discomfort and swelling of the posterior left ankle. A sports medicine colleague had referred her to us after a magnetic resonance imaging (MRI) scan had revealed soft tissue masses. Her symptoms had been progressively becoming worse, with substantial swelling localized to the posterior aspect of her left foot. The initial radiographs demonstrated no bony abnormality, fracture, dislocation, or effusion (Fig. 1). Thus, a MRI study was obtained. MRI before and after intravenous contrast enhancement revealed a 1.4 × 0.6 × 1.0-cm ovoid soft tissue mass connecting to the posterior recess of the posterior subtalar joint. The mass was hypointense on T1 and T2 signals, with mild heterogeneous enhancement of the synovial lining (Fig. 1). Additionally, mild blooming was present on the gradient echo sequences, and a moderate amount of fluid was seen within the posterior superior joint and extending into the posterior recess (Fig. 2). No masses were noted more anteriorly in the subtalar joint region. No other abnormalities of the ligaments, tendons, or bones were present. These imaging findings were
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Fig. 1. (Top Left) Sagittal T1-weighted image demonstrating a hypointense T1 ovoid nodule within the posterior subtalar joint. (Bottom Left) Sagittal gradient recall echo image demonstrating blooming of the ovoid nodule within the posterior subtalar joint. (Right) Lateral radiograph of the left foot demonstrating no salient abnormality.
highly suggestive of PVNS. In addition to the 1 nodule, other small abnormalities were seen, signifying that her disease might not have been of the nodular type but, rather, a form of diffuse PVNS. The patient and her family were given the option to observe and monitor with MRI scans; however, her symptoms continued to worsen, and surgical intervention was chosen. After obtaining informed consent, the patient was scheduled for a posterior subtalar joint synovectomy and excisional biopsy. A posterolateral approach was used with an incision a few centimeters lateral to the Achilles tendon. Careful attention was given to avoid transecting branches of the sural nerve. After incising the capsule, the 2-cm × 1.5-cm oblong mass was identified and corresponded to the mass noted on MRI. The mass was soft and rust colored, further suggesting the diagnosis of PVNS (Fig. 3). The mass was incised en bloc and sent for pathologic examination (Fig. 4). Additional abnormal synovium was identified along the posterior aspect of the subtalar joint, which was red and inflamed, prompting the continued excision of the abnormal synovium in all directions. Most of the cartilage of the subtalar joint was visualized and appeared intact; however, full visualization of the entirety of the joint was not possible through the posterior incision. The incision was closed, and a posterior mold short leg splint was applied. The total duration of surgery was 49 minutes, including 28 minutes of tourniquet time. No intraoperative complications occurred, and the patient tolerated the
Fig. 2. Axial T1-weighted postcontrast fat-saturated image demonstrating heterogeneous enhancement of the ovoid nodule, with enhancing surrounding synovium also present.
ARTICLE IN PRESS D. Novikov et al. / The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
3
At her most recent follow-up visit in May 2017, 5 years after the surgical excision, the patient noted that she has been involved in competitive dancing and cheerleading. She stated that she has been dancing every day of the week and denied any pain in her ankle. The 5-year follow-up MRI study showed no evidence of PVNS recurrence. Discussion
Fig. 3. Gross resection of the mass measuring 1.3 × 0.8 × 0.3 cm with the characteristic brown rust color of pigmented villonodular synovitis.
procedure well. The patient’s left lower extremity was kept nonweightbearing, and she was given instructions to elevate the leg substantially. She was discharged the same day of surgery and was not given any chemical deep vein thrombosis prophylaxis owing to her age. She was to return for a follow-up examination at 1 week after surgery. Postoperatively, the surgical histopathologic examination confirmed the diagnosis of PVNS with classic features.
With an annual average incidence of 1.8 cases/1 million in the US population, PVNS can be considered a rare disease. Furthermore, only 7% of PVNS cases will be localized to the ankle (4). The complex and closely interconnected structures that compose the foot and ankle allow for a very small margin of error in diagnosing and treating disease (3). A recent multicenter retrospective study found that the median interval from the initial clinical symptoms to the diagnosis was ~18 months (6), further underscoring the importance of including PVNS in the differential diagnosis. This delay in diagnosis probably occurs because patients rarely experience obvious symptoms early in the progression of the disease (6), the symptoms are nonspecific, and PVNS shares similar symptoms with other more common diseases, including hemophilia, juvenile rheumatoid arthritis, and septic arthritis. PVNS can affect any joint. However, it most commonly affects the knee, followed by the hip, and is characterized by synovial hyperplasia and hemosiderin deposition inside the tendon sheaths, joints, and bursae. The term villonodular has been used because the proliferation of the synovial membrane can be diffuse or nodular (7). It usually involves only a single joint (8); however, multifocal clinical presentations have been reported (7). Similar to our patient, swelling, stiffness, and diffuse pain of the joint are the most common clinical symptoms at presentation (9). The disease is considered to be benign but locally destructive, and no conclusive evidence of its etiology is
Fig. 4. Histologic sections of the mass demonstrating characteristic hemosiderin-stained multinucleated giant cells and hyperplastic synovial cells associated with pigmented villonodular synovitis (magnification, × 50 to × 100 [Top Images and Bottom Left Image] and ×100 to ×200 [Bottom Right Image]; hematoxylin and eosin stain).
ARTICLE IN PRESS D. Novikov et al. / The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
4
available (6). Some have suggested it is a chronic inflammatory disease (10), and others have deemed it to be more consistent with a tumor that has low metastatic potential (11). Moreover, studies have indicated that metalloproteinases stimulated by local cytokines have a role in the articular cartilage destruction and periarticular bone erosion that typifies PVNS (12), and other studies have reported that this erosion might result from increased intra-articular pressure (13). The ability for PVNS to invade and erode subchondral bone highlights the importance of early diagnosis and initiation of treatment as late recognition can result in significant articular damage. The findings from preliminary radiographs are usually negative, with 1 study reporting minimal radiographic signs in 77% of patients, making MRI the diagnostic tool of choice in the evaluation of PVNS (14). Our patient had typical MRI findings for PVNS including low signals on T1- and T2-weighted images due to hemosiderin deposits, heterogeneous enhancement of the synovial lining likely representing synovial hyperplasia, and blooming on gradient echo sequences characteristic of PVNS (15). The widely accepted treatment of choice for diffuse forms of PVNS is surgery, specifically total or subtotal synovectomy using an either open or arthroscopic approach (14,16). Although our case involved the ankle, other investigators have reported that adjuvant radiotherapy for diffuse PVNS of the knee has been proven to decrease recurrence rates (17). Although treatment of diffuse PVNS in the pediatric population is similar to that for the adult population, radiotherapy as an adjunctive therapy carries the risk of damage to the epiphyseal growth plate and increases the risk of postradiation sarcoma (18), further emphasizing the importance of early detection, especially in the pediatric population. In conclusion, the reported data are sparse on PVNS of the ankle in the pediatric population, likely owing to the rarity of the disease. The purpose of our report was to highlight a rare case of PVNS and underscore the importance of early detection and treatment. References 1. Wang JP, Rancy SK, Dicarlo EF, Wolfe SW. Recurrent pigmented villonodular synovitis and multifocal giant cell tumor of the tendon sheath: case report. J Hand Surg Am 40:537–541, 2015.
2. Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone. In: World Health Organization Classification of Tumours, pp. 109–126, 2002. 3. Chou LB, Ho YY, Malawer MM. Tumors of the foot and ankle: experience with 153 cases. Foot Ankle Int 30:836–841, 2009. 4. Myers BW, Masi AT. Pigmented villonodular synovitis and tenosynovitis: a clinical epidemiologic study of 166 cases and literature review. Medicine (Baltimore) 59:223–238, 1980. 5. Kaneko K, Nakahara D, Tobe M, Iwase H, Inoue Y, Ohbayashi O, Kurosawa H. Pigmented villonodular synovitis of the ankle in an adolescent. Int Orthop 24:234–237, 2000. 6. Xie GP, Jiang N, Liang CX, Zeng JC, Chen ZY, Xu Q, Qi RZ, Chen YR, Yu B. Pigmented villonodular synovitis: a retrospective multicenter study of 237 cases. PLoS One 10:e0121451, 2015. 7. Botez P, Sirbu PD, Grierosu C, Mihailescu D, Savin L, Scarlat MM. Adult multifocal pigmented villonodular synovitis—clinical review. Int Orthop 37:729–733, 2013. 8. Nilsonne U, Moberger G. Pigmented villonodular synovitis of joints. Histological and clinical problems in diagnosis. Acta Orthop Scand 40:448–460, 1969. 9. Stevenson JD, Jaiswal A, Gregory JJ, Mangham DC, Cribb G, Cool P. Diffuse pigmented villonodular synovitis (diffuse-type giant cell tumour) of the foot and ankle. Bone Joint J 95-B:384–390, 2013. 10. Galli M, Ciriello V, Menghi A, Perisano C, Maccauro G, Marzetti E. Localized pigmented villonodular synovitis of the anterior cruciate ligament of the knee: an exceptional presentation of a rare disease with neoplastic and inflammatory features. Int J Immunopathol Pharmacol 25:1131–1136, 2012. 11. Yoon HJ, Cho YA, Lee JI, Hong SP, Hong SD. Malignant pigmented villonodular synovitis of the temporomandibular joint with lung metastasis: a case report and review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 111:e30– e36, 2011. 12. Uchibori M, Nishida Y, Tabata I, Sugiura H, Nakashima H, Yamada Y, Ishiguro N. Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in pigmented villonodular synovitis suggests their potential role for joint destruction. J Rheumatol 31:110–119, 2004. 13. Bhimani MA, Wenz JF, Frassica FJ. Pigmented villonodular synovitis: keys to early diagnosis. Clin Orthop Relat Res 386:197–202, 2001. 14. Baroni E, Russo BD, Masquijo JJ, Bassini O, Miscione H. Pigmented villonodular synovitis of the knee in skeletally immature patients. J Child Orthop 4:123–127, 2010. 15. Friedman T, Chen T, Chang A. MRI diagnosis of recurrent pigmented villonodular synovitis following total joint arthroplasty. HSS J 9:100–105, 2013. 16. De Ponti A, Sansone V, Malchere M. Result of arthroscopic treatment of pigmented villonodular synovitis of the knee. Arthroscopy 19:602–607, 2003. 17. Blanco CE, Leon HO, Guthrie TB. Combined partial arthroscopic synovectomy and radiation therapy for diffuse pigmented villonodular synovitis of the knee. Arthroscopy 17:527–531, 2001. 18. Hong CM, Hing LT. Acute knee pain in a child due to pigmented villonodular synovitis. J Orthop Case Rep 5:78–80, 2015.
Contents lists available at ScienceDirect
The Journal of Foot & Ankle Surgery j o u r n a l h o m e p a g e : w w w. j f a s . o r g
Case Reports and Series
A Rare Incidence of Pigmented Villonodular Synovitis of the Ankle in an Adolescent David Novikov, BS 1, Meghan W. Richardson, MD 2, Corey Ho, MD 3, Elaine S. Gould, MD 4, Fazel A. Khan, MD 5 1Medical
Student, Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY Department of Radiology, Stony Brook University Hospital, Stony Brook, NY 4 Clinical Professor, Department of Radiology & Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY 5Assistant Professor, Department of Orthopaedic Surgery, Stony Brook University Hospital, Stony Brook, NY 2Resident, 3Fellow,
A R T I C L E
I N F O
Level of Clinical Evidence: 4
Keywords: ankle giant cell tumor pediatrics rare tumors synovium
A B S T R A C T
Pigmented villonodular synovitis mostly affects the knee and other large joints such as the hip. Although the disease is most commonly found in adult patients aged 30 to 40 years, rare cases in children and the elderly have been reported. We present the case of an 11-year-old female who was found to have biopsy-proven pigmented villonodular synovitis in her subtalar joint in 2012. Five years after surgical excision, the patient has continued to be involved in competitive dancing and cheerleading without any pain in her ankle. Moreover, follow-up magnetic resonance imaging studies showed no evidence of recurrence. Our case report emphasizes that the disease should not be solely considered in the middle-age population but should be included in the differential diagnosis of the pediatric patient. © 2018 by the American College of Foot and Ankle Surgeons. All rights reserved.
In 1941, Jaffe et al first used the all-encompassing term “pigmented villonodular synovitis” (PVNS) to describe a number of benign, rare tumors of the synovium of the tendon, joints, and bursae (1). Since then, the terminology has changed, with the World Health Organization distinguishing between PVNS and giant cell tumor of the tendon sheath (GCTTS) in 2002, indicating that although both diseases are histologically similar, PVNS can present with diffuse involvement extending outside the joint and its surrounding tissues, in contrast to GCTTS which is a more localized disease process (2). PVNS most commonly affects the knee, followed by other large joints, including the hip. Despite its overall rare occurrence in the foot and ankle, along with GCTTS, it is the most common soft tissue tumor of the foot and ankle (3). Although the disease is most commonly found in adult patients aged 30 to 40 years, rare cases in children and the elderly have been reported (4). Furthermore, PVNS without other congenital abnormalities or sibling involvement is uncommon in children (5). We present the case of an 11-year-old female who had complained of diffuse ankle swelling and was subsequently found to have biopsy-proven PVNS in her subtalar joint. Our case report emphaFinancial Disclosure: None reported. Conflict of Interest: None reported. Address correspondence to: Fazel A. Khan, MD, Department of Orthopaedic Surgery, Stony Brook University Hospital, 101 Nicolls Road, Stony Brook, NY 11794. E-mail address: [email protected] (F. Khan).
sizes that the disease should not be considered limited to those in the middle-age population and should be considered in the differential diagnosis of the pediatric patient. Case Report An otherwise healthy 11-year-old female with no medical or surgical history presented to our clinic as a referral in September 2012 with discomfort and swelling of the posterior left ankle. A sports medicine colleague had referred her to us after a magnetic resonance imaging (MRI) scan had revealed soft tissue masses. Her symptoms had been progressively becoming worse, with substantial swelling localized to the posterior aspect of her left foot. The initial radiographs demonstrated no bony abnormality, fracture, dislocation, or effusion (Fig. 1). Thus, a MRI study was obtained. MRI before and after intravenous contrast enhancement revealed a 1.4 × 0.6 × 1.0-cm ovoid soft tissue mass connecting to the posterior recess of the posterior subtalar joint. The mass was hypointense on T1 and T2 signals, with mild heterogeneous enhancement of the synovial lining (Fig. 1). Additionally, mild blooming was present on the gradient echo sequences, and a moderate amount of fluid was seen within the posterior superior joint and extending into the posterior recess (Fig. 2). No masses were noted more anteriorly in the subtalar joint region. No other abnormalities of the ligaments, tendons, or bones were present. These imaging findings were
1067-2516/$ - see front matter © 2018 by the American College of Foot and Ankle Surgeons. All rights reserved. https://doi.org/10.1053/j.jfas.2018.03.029
ARTICLE IN PRESS 2
D. Novikov et al. / The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
Fig. 1. (Top Left) Sagittal T1-weighted image demonstrating a hypointense T1 ovoid nodule within the posterior subtalar joint. (Bottom Left) Sagittal gradient recall echo image demonstrating blooming of the ovoid nodule within the posterior subtalar joint. (Right) Lateral radiograph of the left foot demonstrating no salient abnormality.
highly suggestive of PVNS. In addition to the 1 nodule, other small abnormalities were seen, signifying that her disease might not have been of the nodular type but, rather, a form of diffuse PVNS. The patient and her family were given the option to observe and monitor with MRI scans; however, her symptoms continued to worsen, and surgical intervention was chosen. After obtaining informed consent, the patient was scheduled for a posterior subtalar joint synovectomy and excisional biopsy. A posterolateral approach was used with an incision a few centimeters lateral to the Achilles tendon. Careful attention was given to avoid transecting branches of the sural nerve. After incising the capsule, the 2-cm × 1.5-cm oblong mass was identified and corresponded to the mass noted on MRI. The mass was soft and rust colored, further suggesting the diagnosis of PVNS (Fig. 3). The mass was incised en bloc and sent for pathologic examination (Fig. 4). Additional abnormal synovium was identified along the posterior aspect of the subtalar joint, which was red and inflamed, prompting the continued excision of the abnormal synovium in all directions. Most of the cartilage of the subtalar joint was visualized and appeared intact; however, full visualization of the entirety of the joint was not possible through the posterior incision. The incision was closed, and a posterior mold short leg splint was applied. The total duration of surgery was 49 minutes, including 28 minutes of tourniquet time. No intraoperative complications occurred, and the patient tolerated the
Fig. 2. Axial T1-weighted postcontrast fat-saturated image demonstrating heterogeneous enhancement of the ovoid nodule, with enhancing surrounding synovium also present.
ARTICLE IN PRESS D. Novikov et al. / The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
3
At her most recent follow-up visit in May 2017, 5 years after the surgical excision, the patient noted that she has been involved in competitive dancing and cheerleading. She stated that she has been dancing every day of the week and denied any pain in her ankle. The 5-year follow-up MRI study showed no evidence of PVNS recurrence. Discussion
Fig. 3. Gross resection of the mass measuring 1.3 × 0.8 × 0.3 cm with the characteristic brown rust color of pigmented villonodular synovitis.
procedure well. The patient’s left lower extremity was kept nonweightbearing, and she was given instructions to elevate the leg substantially. She was discharged the same day of surgery and was not given any chemical deep vein thrombosis prophylaxis owing to her age. She was to return for a follow-up examination at 1 week after surgery. Postoperatively, the surgical histopathologic examination confirmed the diagnosis of PVNS with classic features.
With an annual average incidence of 1.8 cases/1 million in the US population, PVNS can be considered a rare disease. Furthermore, only 7% of PVNS cases will be localized to the ankle (4). The complex and closely interconnected structures that compose the foot and ankle allow for a very small margin of error in diagnosing and treating disease (3). A recent multicenter retrospective study found that the median interval from the initial clinical symptoms to the diagnosis was ~18 months (6), further underscoring the importance of including PVNS in the differential diagnosis. This delay in diagnosis probably occurs because patients rarely experience obvious symptoms early in the progression of the disease (6), the symptoms are nonspecific, and PVNS shares similar symptoms with other more common diseases, including hemophilia, juvenile rheumatoid arthritis, and septic arthritis. PVNS can affect any joint. However, it most commonly affects the knee, followed by the hip, and is characterized by synovial hyperplasia and hemosiderin deposition inside the tendon sheaths, joints, and bursae. The term villonodular has been used because the proliferation of the synovial membrane can be diffuse or nodular (7). It usually involves only a single joint (8); however, multifocal clinical presentations have been reported (7). Similar to our patient, swelling, stiffness, and diffuse pain of the joint are the most common clinical symptoms at presentation (9). The disease is considered to be benign but locally destructive, and no conclusive evidence of its etiology is
Fig. 4. Histologic sections of the mass demonstrating characteristic hemosiderin-stained multinucleated giant cells and hyperplastic synovial cells associated with pigmented villonodular synovitis (magnification, × 50 to × 100 [Top Images and Bottom Left Image] and ×100 to ×200 [Bottom Right Image]; hematoxylin and eosin stain).
ARTICLE IN PRESS D. Novikov et al. / The Journal of Foot & Ankle Surgery ■■ (2018) ■■–■■
4
available (6). Some have suggested it is a chronic inflammatory disease (10), and others have deemed it to be more consistent with a tumor that has low metastatic potential (11). Moreover, studies have indicated that metalloproteinases stimulated by local cytokines have a role in the articular cartilage destruction and periarticular bone erosion that typifies PVNS (12), and other studies have reported that this erosion might result from increased intra-articular pressure (13). The ability for PVNS to invade and erode subchondral bone highlights the importance of early diagnosis and initiation of treatment as late recognition can result in significant articular damage. The findings from preliminary radiographs are usually negative, with 1 study reporting minimal radiographic signs in 77% of patients, making MRI the diagnostic tool of choice in the evaluation of PVNS (14). Our patient had typical MRI findings for PVNS including low signals on T1- and T2-weighted images due to hemosiderin deposits, heterogeneous enhancement of the synovial lining likely representing synovial hyperplasia, and blooming on gradient echo sequences characteristic of PVNS (15). The widely accepted treatment of choice for diffuse forms of PVNS is surgery, specifically total or subtotal synovectomy using an either open or arthroscopic approach (14,16). Although our case involved the ankle, other investigators have reported that adjuvant radiotherapy for diffuse PVNS of the knee has been proven to decrease recurrence rates (17). Although treatment of diffuse PVNS in the pediatric population is similar to that for the adult population, radiotherapy as an adjunctive therapy carries the risk of damage to the epiphyseal growth plate and increases the risk of postradiation sarcoma (18), further emphasizing the importance of early detection, especially in the pediatric population. In conclusion, the reported data are sparse on PVNS of the ankle in the pediatric population, likely owing to the rarity of the disease. The purpose of our report was to highlight a rare case of PVNS and underscore the importance of early detection and treatment. References 1. Wang JP, Rancy SK, Dicarlo EF, Wolfe SW. Recurrent pigmented villonodular synovitis and multifocal giant cell tumor of the tendon sheath: case report. J Hand Surg Am 40:537–541, 2015.
2. Fletcher CDM, Unni KK, Mertens F. Pathology and Genetics of Tumours of Soft Tissue and Bone. In: World Health Organization Classification of Tumours, pp. 109–126, 2002. 3. Chou LB, Ho YY, Malawer MM. Tumors of the foot and ankle: experience with 153 cases. Foot Ankle Int 30:836–841, 2009. 4. Myers BW, Masi AT. Pigmented villonodular synovitis and tenosynovitis: a clinical epidemiologic study of 166 cases and literature review. Medicine (Baltimore) 59:223–238, 1980. 5. Kaneko K, Nakahara D, Tobe M, Iwase H, Inoue Y, Ohbayashi O, Kurosawa H. Pigmented villonodular synovitis of the ankle in an adolescent. Int Orthop 24:234–237, 2000. 6. Xie GP, Jiang N, Liang CX, Zeng JC, Chen ZY, Xu Q, Qi RZ, Chen YR, Yu B. Pigmented villonodular synovitis: a retrospective multicenter study of 237 cases. PLoS One 10:e0121451, 2015. 7. Botez P, Sirbu PD, Grierosu C, Mihailescu D, Savin L, Scarlat MM. Adult multifocal pigmented villonodular synovitis—clinical review. Int Orthop 37:729–733, 2013. 8. Nilsonne U, Moberger G. Pigmented villonodular synovitis of joints. Histological and clinical problems in diagnosis. Acta Orthop Scand 40:448–460, 1969. 9. Stevenson JD, Jaiswal A, Gregory JJ, Mangham DC, Cribb G, Cool P. Diffuse pigmented villonodular synovitis (diffuse-type giant cell tumour) of the foot and ankle. Bone Joint J 95-B:384–390, 2013. 10. Galli M, Ciriello V, Menghi A, Perisano C, Maccauro G, Marzetti E. Localized pigmented villonodular synovitis of the anterior cruciate ligament of the knee: an exceptional presentation of a rare disease with neoplastic and inflammatory features. Int J Immunopathol Pharmacol 25:1131–1136, 2012. 11. Yoon HJ, Cho YA, Lee JI, Hong SP, Hong SD. Malignant pigmented villonodular synovitis of the temporomandibular joint with lung metastasis: a case report and review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 111:e30– e36, 2011. 12. Uchibori M, Nishida Y, Tabata I, Sugiura H, Nakashima H, Yamada Y, Ishiguro N. Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in pigmented villonodular synovitis suggests their potential role for joint destruction. J Rheumatol 31:110–119, 2004. 13. Bhimani MA, Wenz JF, Frassica FJ. Pigmented villonodular synovitis: keys to early diagnosis. Clin Orthop Relat Res 386:197–202, 2001. 14. Baroni E, Russo BD, Masquijo JJ, Bassini O, Miscione H. Pigmented villonodular synovitis of the knee in skeletally immature patients. J Child Orthop 4:123–127, 2010. 15. Friedman T, Chen T, Chang A. MRI diagnosis of recurrent pigmented villonodular synovitis following total joint arthroplasty. HSS J 9:100–105, 2013. 16. De Ponti A, Sansone V, Malchere M. Result of arthroscopic treatment of pigmented villonodular synovitis of the knee. Arthroscopy 19:602–607, 2003. 17. Blanco CE, Leon HO, Guthrie TB. Combined partial arthroscopic synovectomy and radiation therapy for diffuse pigmented villonodular synovitis of the knee. Arthroscopy 17:527–531, 2001. 18. Hong CM, Hing LT. Acute knee pain in a child due to pigmented villonodular synovitis. J Orthop Case Rep 5:78–80, 2015.