case_images: PMC7468654_01
case_images: Plain radiograph of the left elbow obtained at the first visit to our department. A large transparent area is observed in the posterior lateral humeral bone (arrow). The vertical range is 29.8 mm, and lateral range is 33.0 mm in the anteroposterior view.
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case_images: fig1
case_images: Plain radiography showed a 29.7 mm x 21.0 mm of large geode area in the left humeral lateral epicondyle (Figure 1).
case_images: Magnetic resonance imaging of the left elbow obtained at the first visit to our department. (a) T1-weighted image (T1WI); (b) fat-suppressed T2-weighted image (T2WI-Fs); and (c) gadolinium-enhanced and fat-suppressed T1-weighted image (Gd-T1WI-Fs). A large low-intensity area is observed in T1WI, and high-intensity area is observed in T2WI-Fs. In Gd-T1WI-Fs, a large low-intensity area enhanced peripherally is noted (arrow). It seems as a large cyst surrounded by synovium.
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case_images: fig2
case_images: T1-weighted images, and enhanced peripheral area of the geode in gadolinium-enhanced T1-weighted images (Figure 2). These images suggested that the cyst consisted of fluid with peripheral synovitis. The patient fulfilled 2010 ACR/EULAR classification criteria for RA and was diagnosed with RA.
case_images: Transition of (a) erythrocyte sedimentation rate (ESR), (b) C-reactive protein (CRP), (c) matrix metalloproteinase (MMP)-3, and (d) disease activity score (DAS) 28. After visiting our department, the patient was treated with methotrexate. From August 22, 2016, the patient started to receive tocilizumab, and all laboratory data and DAS28 improved remarkably and immediately after administration.
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case_images: fig3
case_images: However, the disease activity score (DAS) 28 was still high (Figure 3), and radiography indicated no evident improvement of the large geode in the left humeral lateral epicondyle (Figure 4). After subcutaneous injection of tocilizumab, the patient reported articular pain, laboratory data showed inflammation factor, and DAS28 immediately improved (Figure 3).
case_images: Plain radiograph of the left elbow at 10 months since the start of oral methotrexate. The large transparent area still remained, and poor repair is noted in the posterior lateral humeral bone (arrow).
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case_images: fig4
case_images: However, the disease activity score (DAS) 28 was still high (Figure 3), and radiography indicated no evident improvement of the large geode in the left humeral lateral epicondyle (Figure 4).
case_images: Plain radiograph of the left elbow at 10 months since the administration of subcutaneous tocilizumab injection. The transparent area gradually decreased, and bone formation progressed from the peripheral area (arrow). The size of evident geode is 10.8 mm x 8.3 mm.
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case_images: fig5
case_images: Furthermore, the large geode in the left humeral lateral epicondyle gradually improved, and progression of bone formation from peripheral area was shown in radiography (Figure 5).
case_images: Plain radiograph of the left elbow at one month after administration of denosumab every three months. The transparent area showed little improvement effect compared to Figure 5 (arrow).
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case_images: fig6
case_images: However, additional denosumab showed no eminent effect on geode repair (Figure 6).
case_images: Magnetic resonance image of the left elbow, 3 years 5 months after the first visit to our department. (a) T1-weighted image (T1WI); (b) fat-suppressed T2-weighted image (T2WI-Fs); and (c) gadolinium-enhanced short T1 inversion recovery image (Gd-SPIR). The high-intensity area appeared from the peripheral cavity and internal low-intensity area became slightly brighter in T1WI. The peripheral high-intensity area was considered to demonstrate replaced bone marrow fat. The high-intensity area is noted in T2WI-Fs, but the size and signal strength decreased. In Gd-SPIR, the low-intensity area became slightly brighter, and the peripherally enhanced area seemed to be weaker (arrow).
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case_images: PMC7468654_01_CRIRH2020-8899391.007.jpg
case_images: fig7
case_images: In contrast, MRI showed decreased area in the geode and diminished peripheral contrast enhancement effect compared to MRI before tocilizumab administration (Figure 7).