Paediatric post-traumatic osseous cystic lesion following a distal radial fracture

Abstract

Post-traumatic osseous cystic lesions are a rare complication in children. An aetiology of intramedullary fat seepage through the damaged bone cortex and its entrapment within the subperiosteum has been proposed. These lesions run a benign course and usually resolve spontaneously. The presence of fatty marrow gives it a distinct appearance which aids in its diagnosis and differentiation from other bone lesions. This case demonstrates a fat-fluid level within the subperiosteal cystic lesion in Magnetic Resonance Imaging (MRI) and this is a typical feature of post-traumatic cystic lesion in a child. Recognition of this imaging feature allows for a confident diagnosis, cutting down on unnecessary, potentially invasive investigations.

Keywords: Magnetic Resonance Imaging; Post-traumatic; cyst; fracture; osseous.

Figure 1

13-year-old male with post-traumatic osseous cystic lesion following a distal radial fracture. FINDINGS: A, Posteroanterior and B, Lateral radiographs of the left wrist demonstrate fracture of left distal radius (arrows), where the fracture line appears extending to the epiphyseal plate with mild dorsal displacement of the radial epiphysis suggestive of Salter-Harris Type 2 fracture of the distal radius. TECHNIQUE: Siemens, 45 kVp, 2.4 mAs

Figure 2

13-year-old male with post-traumatic osseous cystic lesion following a distal radial fracture. FINDINGS: A, Posteroanterior and B, Lateral follow up radiographs of the left wrist of the same patient reveal callus formation and periosteal reaction in keeping with healing process of the fracture (arrows), at 4 weeks after being treated with fibreglass cast. TECHNIQUE: Siemens, 45 kVp, 2.4 mAs

Figure 3

13-year-old male with post-traumatic osseous cystic lesion following a distal radial fracture. FINDINGS: A, Posteroanterior and B, Lateral radiographs demonstrate a well-circumscribed lucent lesion (arrows) without sclerotic rim based on the posterior cortex without scalloping adjacent to the prior fracture site at 3 months after the initial injury. TECHNIQUE: Siemens, 45 kVp, 2.4 mAs

Figure 4

13-year-old male with post-traumatic osseous cystic lesion following a distal radial fracture. FINDINGS: Axial T1-weighted MR image (A) and axial T1-weighted fat-suppressed MR image (B) of the same patient’s wrist demonstrating a subperiosteal cystic lesion along the dorsal cortex, containing an upper layer of high T1-weighted (red asterisk) and low T1-weighted fat-suppressed signal intensity (white asterisk) consistent with fat content. Axial T2-weighted fat-suppressed MR image (C) of the same patient’s wrist showing the lower layer of high T2-weighted signal intensity (black asterisk) and low T1W signal (seen in A) likely to represent chronic subperiosteal haematoma. Axial T1-weighted fat-suppressed post intravenous gadolinium (D) demonstrates mild enhancement along the periosteal reaction and in adjacent soft tissue (arrows). Sagittal T1-weighted fat-suppressed post intravenous gadolinium (E) demonstrates mild enhancement along the periosteal reaction and in adjacent soft tissue (arrows). TECHNIQUE: MRI. Magnetic Strength: 3.0 Tesla. Axial T1W: TE 12ms, TR 750; Axial T1W fat-suppressed: TE 12ms, TR 750; Axial T2W fat-suppressed: TE 79ms, TR 3410; Axial T1W fat-suppressed post contrast: TE 13, TR 650; Sagittal T1W fat-suppressed post contrast: TE 12, TR 700. Contrast: Intravenous Dotarem 10mls.