summary Unicameral Bone Cysts are non-neoplastic, serous fluid-filled bone lesions most commonly found in the proximal humerus. The condition typically presents in patients < 20 years of age with a pathological fracture through the lesion. Diagnosis is made with radiographs showing a central, lytic, well-demarcated metaphyseal lesions with cystic expansion and a characteristic "fallen leaf" sign. Treatment is usually immobilization for proximal humerus lesions with pathologic fracture. Surgical curettage and bone grafting is indicated for pathologic fractures that have a high rate of refracture and malunion. Epidemiology Demographics age usually found in patients <20 years of age Anatomic location location usually found in the proximal humerus of young patients can be found in other locations including proximal femur, distal tibia, ilium, calcaneus, and occasionally metacarpals, phalanges, or distal radius arises in the metaphysis adjacent to physis and progresses toward the diaphysis with bone growth Classification Classification is important as it impacts treatment active if cyst is adjacent to the physis latent if normal bone separates cyst from physis Presentation Symptoms most asymptomatic unless fracture occurs (usually with minor trauma) presents with pain from a pathologic fracture in ~50% Imaging Radiographs central, lytic, well-demarcated metaphyseal lesion (2-3% cross physis) cystic expansion with symmetric thinning of cortices "fallen leaf" sign (pathologic fracture with fallen cortical fragment in base of empty cyst is pathognomonic) trabeculated appearance after multiple fractures MRI very dark on T1 very bright on T2 gadolinium shows classic rim enhancement of a cystic lesion Bone scan is variable, but usually warm Labs Specific laboratory tests usually not required Histology Characteristic findings cyst with thin fibrous lining containing fibrous tissue, giant cells, and hemosiderin pigment chronic inflammatory cells may be found in small numbers cementum spherules (calcified eosinophilic fibrinous material) in 10% uniform population of spindle cells without nuclear atypia Biopsy usually indicated for questionable diagnosis Differential ABC is more expansive than UBC (UBC lesion usually not wider than physis) Telangiectatic osteosarcoma Differential of Unicameral Bone Cyst "Bubbly" lytic lesion on xray Treatment is USUALLY Aspiration and Injection Treatment is OCCASIONALLY curettage and bone grafting. UBC o o o ABC o NOF o o Enchondroma o Treatment Nonoperative immobilization alone indications proximal humerus lesions with pathologic fracture (15% of lesions fill in with native bone after acute fracture) aspiration/methylprednisolone acetate injection indications active cysts (communicates with physis) in the proximal humerus technique usually requires several injections, especially in very young children bone marrow injections have recently been reported to be effective Operative curettage and bone grafting +/- internal fixation based on tumor location indications symptomatic latent cysts that have not responded to steroid injections latent cysts in the proximal femur that are a structural concern and at risk for fracture and osteonecrosis proximal femoral lesions with a pathologic fracture have a high rate of refracture and malunion when treated nonoperatively therefore, internal fixation is recommended contraindications avoid in active lesions as communication with physis may lead to growth arrest Prognosis As a patient approaches skeletal maturity, a UBC will often decrease in size and may heal after growth is complete Fracture healing usually does not lead to cyst resolution Requires close follow up while in active phase due to recurrence and risk of fracture or growth arrest Treatment with Intralesional corticosteroid, demineralized bone matrix, and autologous bone marrow injection may decrease recurrence
QUESTIONS 1 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Previous Next (OBQ15.162) A 10-year-old boy injured his right shoulder playing lacrosse. He denies previous shoulder pain or injury. Radiographs of the shoulder are shown in Figure A. What is the next best step in management? QID: 5847 FIGURES: A Type & Select Correct Answer 1 Urgent biopsy 4% (150/3581) 2 CT scan of arm 4% (127/3581) 3 Whole body bone scan 2% (73/3581) 4 Open reduction and plate fixation 1% (50/3581) 5 Sling for comfort 88% (3168/3581) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ14.187) A 16-year-old girl presents with hip and thigh pain for 3 months. Examination reveals an antalgic gait. A radiograph, coronal MRI scans (T1 pre- and post-contrast, and T2), and biopsy are shown in Figures A through E. What is the most likely diagnosis? QID: 5597 FIGURES: A B C D E Type & Select Correct Answer 1 Unicameral bone cyst 61% (2498/4096) 2 Aneurysmal bone cyst 11% (470/4096) 3 Fibrous dysplasia 14% (555/4096) 4 Osteofibrous dysplasia 8% (318/4096) 5 Eosinophilic granuloma 6% (230/4096) L 2 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ11PA.92) What is the most common anatomical site for unicameral bone cysts in children? QID: 4117 Type & Select Correct Answer 1 Distal humerus 1% (26/4381) 2 Proximal humerus 91% (3998/4381) 3 Distal femur 4% (159/4381) 4 Proximal tibia 3% (119/4381) 5 Tibial shaft 1% (58/4381) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ11.268) An 11-year-old boy presents with acute right arm pain after throwing a baseball. He is otherwise healthy and has no other complaints. Radiograph and CT scan of the lesion are shown in Figures A and B. What is the most appropriate treatment? QID: 3691 FIGURES: A B Type & Select Correct Answer 1 Biopsy 8% (188/2292) 2 Immobilization 88% (2027/2292) 3 Intramedullary nailing and chemotherapy 2% (38/2292) 4 Wide resection and radiation therapy 1% (27/2292) 5 Amputation 0% (6/2292) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ08.63) A 9-year-old child presents to your office after he felt a painful snap in his arm while throwing a baseball. He is otherwise in good health and has no family history of disease. A radiograph of his arm is shown in Figure A. What is the next step in your management? QID: 449 FIGURES: A Type & Select Correct Answer 1 Sling for comfort 83% (1873/2247) 2 Tumor staging 2% (39/2247) 3 Biopsy 12% (263/2247) 4 Open reduction with internal fixation 2% (44/2247) 5 Intramedullary nailing 1% (20/2247) L 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK This is an AAOS Self Assessment Exam (SAE) question. Orthobullets was not involved in the editorial process and does not have the ability to alter the question. If you prefer to hide SAE questions, simply turn them off in your Learning Goals. (SAE07PE.38) Figure 16 shows the radiograph of a 7-year-old boy who sustained a pathologic fracture of the left humerus 1 day ago. Initial management should consist of QID: 6098 FIGURES: A Type & Select Correct Answer 1 a sling and swathe. 75% (586/777) 2 needle biopsy of the lesion. 14% (107/777) 3 a corticosteroid injection of the lesion. 1% (6/777) 4 curettage and bone packing of the lesion. 9% (67/777) 5 insertion of an intramedullary rod. 1% (6/777) L 3 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic (OBQ07.51) An 8-year-old boy injures his arm pulling open a car door. A radiograph is shown in Figure A. Which of the following is the most likely diagnosis and preferred initial treatment? QID: 712 FIGURES: A Type & Select Correct Answer 1 Giant cell tumor of bone, Open biopsy and curettage of tumor 2% (38/1905) 2 Unicameral bone cyst, Aspiration of fluid and injection of bone cement 9% (172/1905) 3 Non-Ossifying Fibroma, Radiation 1% (19/1905) 4 Unicameral bone cyst, Sling and swath 88% (1668/1905) 5 Telangietic osteosarcoma, Chemotherapy 0% (1/1905) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (SBQ07PE.38) An 8-year-old boy complains of left shoulder pain after a collision with his younger brother. He was asymptomatic prior to the incident. Which of the following treatments is most appropriate at this time? QID: 1523 FIGURES: A Type & Select Correct Answer 1 Aspiration and injection of methylprednisolone acetate 3% (45/1758) 2 Open reduction, internal fixation 4% (65/1758) 3 Initiation of radiation and chemotherapy 1% (14/1758) 4 Immobilization in sling 92% (1614/1758) 5 Radiofrequency ablation 1% (11/1758) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ05PA.99) A 10-year-old boy complains of shoulder pain after falling while skateboarding. His injury radiograph is shown in Figure A. What is the most appropriate next step in treatment? QID: 2084 FIGURES: A Type & Select Correct Answer 1 Immobilization alone 79% (1950/2472) 2 MRI 10% (237/2472) 3 Open reduction, percutaneous fixation 2% (41/2472) 4 Aspiration/methylprednisolone acetate injection 2% (45/2472) 5 Curettage and bone grafting 8% (189/2472) L 2 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic (OBQ05.144) A 7-year old boy experienced severe right hip pain following ice-skating. He previously had no hip pain and is otherwise healthy. Radiographs are shown in figures A and B. What is the recommended treatment ? QID: 1030 FIGURES: A B Type & Select Correct Answer 1 Open biopsy and pathological staging without fracture fixation 9% (187/2153) 2 Open reduction and internal fixation with bone grafting of the bone cyst 81% (1750/2153) 3 Bedrest for 4 weeks followed by progressive weight-bearing as tolerated 3% (75/2153) 4 Immediate hip spica casting 6% (124/2153) 5 Tibial traction pin with 4 weeks of skeletal traction followed by open biopsy 1% (12/2153) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (OBQ04.54) A 15-year-old boy twists his ankle and is brought to the emergency room. Radiographs are shown in Figure A. What is the most likely progression of the this lesion as the child reaches skeletal maturity? QID: 1384 FIGURES: A Type & Select Correct Answer 1 Increase in size and involve the entire bone 2% (26/1432) 2 Decrease in size and may disappear altogether 86% (1227/1432) 3 Turn into a malignant tumor 0% (4/1432) 4 Remain unchanged 11% (161/1432) 5 Lead to deformity of the affected bone 1% (13/1432) L 1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic
All Videos (1) Podcasts (1) Login to View Community Videos Login to View Community Videos oncology Orthopedic Oncology Course - Radiolucent Lesions of Bone (GCT, ABC, UBC) - Lecture 7 Mohammed Al Sobeai Pathology - Unicameral Bone Cyst A 3/1/2017 1080 views 5.0 (4) Pathology⎪Unicameral Bone Cyst Pathology - Unicameral Bone Cyst Listen Now 11:30 min 6/4/2020 500 plays 4.5 (2)
Pathological Humeral Shaft Fracture in 17M (C101807) Alexander Wilton Pathology - Unicameral Bone Cyst C 10/3/2021 343 9 0 Femoral bone lesion in a 50M (C101059) modar yousif Pathology - Unicameral Bone Cyst E 4/2/2018 336 3 4 UBC (C2191) Ibrahim Hussein Pathology - Unicameral Bone Cyst E 4/6/2015 122 0 11 See More See Less