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Copyrights © 2014 The Korean Society of RadiologyINTRODUCTION
Intra-articular tumors or tumor-like lesions, occasionally en- countered in the locomotor system, often include a variety of sy- novial proliferative disease, infectious granulomatous disease, benign and malignant tumors such as pigmented villonodular synovitis (PVNS), synovial hemangioma, lipoma arborescens, tuberculous arthritis, rheumatoid arthritis, and synovial sarco- ma (1). Intra-articular nodular fasciitis is extremely rare. Nodu- lar fasciitis is a benign soft tissue lesion consisting of myofibro- blastic proliferation. Nodular fasciitis is usually self-limiting and arising most commonly in the subcutaneous and fascial tissues (2). Here we describe a rare case of intra-articular nodular fasci- itis of the knee.
CASE REPORT
A 13-year-old boy presented with left knee pain and tender- ness for 3 months. He had an uncertain history of knee sprain 3 months ago. After the knee sprain incident, his symptoms had
been gradually worsened. The patient visited a private orthope- dic surgery clinic and underwent knee joint aspiration several times. However, the symptoms did not improve. After undergo- ing a magnetic resonance imaging (MRI) at a local radiological clinic, the patient was referred to the orthopedic department at our hospital. Physical examination revealed a palpable tender mass in the anterior knee, medial to the patella. Range of mo- tion of the joint was slightly restricted in the flexion. There was no instability of the joint or sign of meniscal tear. Radiographs of the knee showed no abnormality. MRI of the knee showed a solitary well defined mass-like lesion (measuring 2 × 2 cm) which was located intra-articularly along the joint capsule infer- omedial aspect to the patella. The lesion was iso- to slightly hy- per-intense compared to that of adjacent normal muscle on T1- weighted images and hyper-intense on fast spin echo on gradient T2-weighted images. Area of low signal intensity suggesting col- lagen-rich stroma was observed in ventral aspect of the mass.
Joint effusion was evident on T2-weighted images (Fig. 1). Con- trast enhancement study was not included.
Pre-operative radiological impression was intra-articular be-
Case Report
pISSN 1738-2637 / eISSN 2288-2928 J Korean Soc Radiol 2014;71(5):254-257 http://dx.doi.org/10.3348/jksr.2014.71.5.254
Received June 12, 2014; Accepted August 26, 2014 Corresponding author: Kil Ho Cho, MD Department of Diagnostic Radiology, Yeungnam University College of Medicine, 170 Hyeonchung-ro, Nam-gu, Daegu 705-717, Korea.
Tel. 82-53-620-3045 Fax. 82-53-653-5484 E-mail: [email protected]
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distri- bution, and reproduction in any medium, provided the original work is properly cited.
Nodular fasciitis, a benign soft tissue tumor consisting of myofibroblastic prolifera- tion, is commonly located in the subcutaneous or inter- or intra-muscular layer of extremites. Intra-articular nodular fasciitis is extremely rare. We report a case of MRI findings of a nodular fasciitis in the knee of a 13-year-old boy which was re- moved by arthroscopic surgery and pathologically confirmed.
Index terms Intra-Articular Nodular Fasciitis Knee
MRI
Intra-Articular Nodular Fasciitis of the Knee: A Case Report of MRI Findings
1무릎 관절내 결절성 근막염: 자기공명영상 증례 보고1
O Hyun Kwon, MD
1, Kil Ho Cho, MD
1, Jang Ho Suh, MD
1, Joon Hyuk Choi, MD
2Departments of 1Radiology, 2Pathology, Yeungnam University College of Medicine, Daegu, Korea
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tissues of the extremities of adults between 20 and 40 years of age (3). Intra-articular occurrence of nodular fasciitis is ex- tremely rare, especially in pediatric patients. To the best of our knowledge, a search of the English literature revealed only a few case reports of intra-articular nodular fasciitis (3-7). In pediatric patients, a few cases have been reported only in the ankle, knee, and glenohumeral joint (3-5).
Histologically, nodular fasciitis is composed of plump, imma- ture-appearing fibroblasts and myofibroblasts in irregular fasci- cles, regardless of whether they are predominantly fibrous or myxoid. In general, these cells differ little in size with oval shape of pale stained nuclei and prominent nucleoli. Mitotic figures are fairly common. However, atypical mitoses are virtually never seen. Immunohistochemically, the cells stain positively for smooth-muscle actin but negatively for desmin, suggesting a nign solid mass. At arthroscopy, a white, well-defined and encap-
sulated mass was attached to the joint capsule in the inferomedial aspect in the knee joint. The mass was excised arthroscopically.
Histopathological examination revealed spindle-shaped myofi- broblastic cell proliferation in a variably collagenous or myxoid stroma. Nuclear atypia or mitotic figures were absent. Based on immunohistochemical study, spindle cells were diffusely posi- tive for a-smooth-muscle actin but negative for desmin. These histological features were consistent with those of nodular fasci- itis (Fig. 2).
DISCUSSION
Nodular fasciitis is a benign self-limiting reactive process most commonly encountered in the subcutaneous fascial soft
Fig. 1. Magnetic resonance imaging in a 13-year-old man with intra-articular nodular fasciitis of left knee.
A. Fast spin echo axial T2-weighted image shows a well defined mass (arrowheads) with a increased signal intensity compared to normal muscle.
Area of low signal intensity suggesting collagen-rich stroma is seen in ventral aspect of the mass. This mass is located in the joint capsule of in- feromedial aspect of patella. Joint effusion is also noted.
B. Sagittal T1-weighted image reveals iso- to slightly high signal intensity to the normal muscle.
C. Gradient coronal T2-weighted image demonstrates well defined homogeneous high signal intensity.
D. Coronal T1-weighted image also shows well defined iso- to slightly high signal intensity of the mass.
A B C D
Fig. 2. Pathologic images of the intra-articular nodular fasciitis.
A. Microphotograph shows myofibroblastic cell proliferation in the subsynovial layer (H&E; × 40).
B. Mixed collagenous and myxoid stroma is seen (H&E; × 100).
C. Immunohistochemical staining shows a positive reaction with a-smooth-muscle actin (× 200).
B
A C
Intra-Articular Nodular Fasciitis of the Knee
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J Korean Soc Radiol 2014;71(5):254-257 jksronline.orgmay be included to the list of differential diagnosis of intra-ar- ticular tumor or tumor-like lesions, although its MRI findings are nonspecific.
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2. Weiss Sw, Goldblum Jr. Enzinger and Weiss’s soft tissue tumors, 5th ed. St. Louis: Mosby, 2008:190-194
3. Hornick JL, Fletcher CD. Intraarticular nodular fasciitis--a rare lesion: clinicopathologic analysis of a series. Am J Surg Pathol 2006;30:237-241
4. Lädermann A, Kindynis P, Taylor S, Ceroni D, Hoffmeyer P, Kaelin A, et al. Articular nodular fasciitis in the glenohu- meral joint. Skeletal Radiol 2008;37:663-666
5. Gans I, Morrison MJ 3rd, Chikwava KR, Wells L. Intra-ar- ticular nodular fasciitis of the knee in a pediatric patient.
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6. Matsuzaki T, Akisue T, Kishimoto K, Kishimoto S, Imabori M, Hara H, et al. Intra-articular nodular fasciitis of the knee: a rare cause of recurrent hemarthrosis. Rheumatol Int 2012;32:1691-1694
7. Hagino T, Ochiai S, Sato E, Watanabe Y, Senga S, Kondo T, et al. Intraarticular nodular fasciitis causing limitation of knee extension: a case report. Knee 2010;17:424-427 8. Coyle J, White LM, Dickson B, Ferguson P, Wunder J, Nara-
ghi A. MRI characteristics of nodular fasciitis of the mus- culoskeletal system. Skeletal Radiol 2013;42:975-982 9. Leung LY, Shu SJ, Chan AC, Chan MK, Chan CH. Nodular
fasciitis: MRI appearance and literature review. Skeletal Radiol 2002;31:9-13
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smooth-muscle cell differentiation (2). In the present case, his- tological findings and immunohistochemical staining proper- ties were consistent with typical nodular fasciitis.
Clinically, extra-articular nodular fasciitis commonly presents as a rapidly growing painful mass in the subcutaneous fascia (2).
However, intra-articular nodular fasciitis grows relatively slow, with a longer preoperative history in a report (3). Patients with intra-articular nodular fasciitis typically complain of pain, swell- ing, restriction of joint motion, and a palpable mass around the joint (2, 3, 7). The pathogenesis of nodular fasciitis is currently unclear. Some described that nodular fasciitis was a reactive le- sion related to trauma, others suggested that nodular fasciitis had chromosomal abnormalities of neoplastic origin (3).
MRI findings of extra-articular nodular fasciitis are nonspecific, with iso- to slightly hyper-intense signal intensity on T1-weighted images and hyper-intense signal intensity on T2-weighted images.
Inhomogenous enhancement is common (8, 9). Surrounding edema, trans-compartmental spread and osseous changes are also reported (8).
Although information on imaging studies for intra-articular nodular fasciitis is limited, the current case showed nonspecific findings on MRI images, with homogeneous iso to low signal intensity on T1-weighted images and a heterogeneous, low to high signal intensity on T2-weighted images as reported previ- ously (3-7). In this present case, conventional MRI with no con- trast study showed nonspecific signal intensity of the lesion sim- ilar to previous reports, resulting in difficulty in making a precise pre-operative diagnosis on MRI. Differential diagnoses include PVNS, synovial hemangioma, lipoma arborescens, rheumatoid arthritis, and infectious granulomatous disease such as tubercu- lous arthritis (1, 10).
This report has several limitations. Firstly, imaging sequences were not fully performed in every cross-sectional plane. Sec- ondly, additional imaging study such as ultrasound or follow-up MRI was not performed.
In conclusion, extremely rare intra-articular nodular fasciitis
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무릎 관절내 결절성 근막염: 자기공명영상 증례 보고1
권오현
1· 조길호
1· 서장호
1· 최준혁
2결절성 근막염은 섬유근모세포의 증식에 의하여 발생하는 연부조직 종양이다. 사지의 피하층 또는 근육 내 또는 사이에 가장 잘 생기는 것으로 알려져 있으나, 관절내 결절성 근막염은 극히 드물다. 저자들은 13세 남아의 무릎 관절내에 생긴 연부조직종괴를 관절경하 종양절제술로 제거하고 조직병리검사에서 결절성 근막염으로 확진된 관절내 증례를 자기공명 영상 소견과 함께 보고하고자 한다.
영남대학교 의과대학 1영상의학과학교실, 2병리학교실
