Osteosarcoma of the Humerus Developing as Second Malignancy in the Irradiation Field Outside the Primary Tumor: 11 Years after Ewing Sarcoma of the Scapula and 29 Years after Breast Cancer

Purpose: Development of sarcoma is a known late rare negative side effect of radiotherapy. We add two cases to emphasize the need for open-end follow-up and critical evaluation to avoid misinterpretation. Patients, Methods, and Results: Two patients developed osteosarcoma as a second malignancy in the humerus after adjuvant radiotherapy of a primary tumor not directly involving the later affected bone. The first patient had a Ewing sarcoma of the scapula at age 13 years. Though after neoadjuvant chemotherapy the resected specimen showed only fibrotic necrotic areas within clear resection margins, the study group indicated adjuvant radiotherapy in a field including the shoulder joint. At age 24 years she developed an osteosarcoma of the humeral head, which was resected and reconstructed with a proximal humerus endoprosthesis. She is alive without disease at age 32 years. The second patient presented with an osteosarcoma of the proximal humerus 29 years after irradiation for breast cancer including the shoulder joint. The sarcoma was misinterpreted as radiation-induced necrosis and the patient was treated with a reverse shoulder endoprosthesis. Pathologic examination of the resected humeral head then showed a typical osteosarcoma. Two years later the humeral reverse shoulder implant was resected and a proximal humerus tumor prosthesis implanted leaving the original glenosphere. Conclusions: In both cases radiation-induced osteosarcoma developed in bone not affected by the primary cancer. Protecting uninvolved structures must be warranted in the planning of radiotherapy. The long latency between the primary and second cancer mandates long-term—best indefinite—follow-up, as with appropriate treatment of a radiation-induced osteosarcoma good healing rates comparable to those of primary osteosarcoma can still be achieved.

Ankle Arthrodesis Nail Combined with Locking Compression Plate to Stabilize Two-Level Pathologic Tibial Fractures

Treatment of fragility fractures of the distal tibia in the elderly is demanding because of osteopenic bone quality, the delicate soft tissue cuff and frequent critical circulation. We report the case of two-level tibial pseudarthroses in an 83- year-old woman caused by multiple myeloma successfully stabilized by a long ankle arthrodesis nail combined with locking compression plate osteosynthesis. This case is unique, as to our best knowledge, herein diaphyseal fractures were treated for the first time using a technique reported hitherto primarily for fragility ankle and pilon fractures.

Treatment of Unicameral and Aneurysmal Bone Cysts by Minimally Invasive Percutaneous Injection of Grafton DBF Putty Using the Kyphon Cement Delivery System

Background: Simple Unicameral and Aneurysmal Bone Cysts are benign lesions that may heal spontaneously especially after fracture which may be the first symptom. However, often size increases causing pain, and complications of fractures can severely compromise the patient. Aim: The results in a series of cases treated minimally invasive using a new device for the application of allogenic bone material appear highly promising and shall be presented. Patients and Methods: Eight consecutive patients with symptomatic Unicameral Bone Cysts (UBC) were treated by percutaneous instillation of Grafton? DBF Putty (demineralised allogenic bone containing fibers) mixed with autologous bone marrow using the Kyphon? Cement Delivery System (Medtronic), which allows the injection of this high viscosity paste by controlled high pressure. Five patients with Aneurysmal Bone Cysts (ABC) were treated accordingly after inactivation by Aethoxysclerol 3% and lacking bone formation. Using this approach a high rate of bone regeneration was observed in these patients at 8 months to 5 years follow-up (f/u). Conclusion: The presented technique of a minimally invasive biologic treatment led to highly satisfying results using the Grafton? DBF Putty with its higher potential for bone regeneration than demineralized bone matrix not containing fibres (DBM).

Intraarticular Nodular Fasciitis in the Knee Joint with <i>USP6</i>-Gene Rearrangement<br/>—A Case Report with Special Attention to Diagnostics of Intraarticular Lesions

Background: Nodular fasciitis (NF) is currently considered a self-limited clonal neoplastic process. It shares the rearrangement of USP6-gene with aneurysmal bone cysts and myositis ossificans. The presented case is of interest as this is a rare site of presentation of NF;so far only few single cases of intraarticular NF have been reported with documented USP6-gene rearrangement. Intraarticular neoplasias of the knee joint are rare;the most frequent being tenosynovial giant cell tumor (TSGCT). Given a nationwide annual incidence rate of 14 for the lower extremity and about 75% affecting the knee joint about 10 new cases involving the knee joint can be expected per 1 million persons/year. All other types of benign neoplasms are comparably rare while malignant intraarticular processes are extremely rare with most of them reported as single case studies. Aim: We report our case to emphasize the importance of preoperative diagnostics including the option of biopsy. Intraarticular malignant processes are extremely rare and frequently are operated on accidently with negative consequences for the patient. Tactics and techniques to treat benign processes depend on the correct pathologic diagnosis. Case presentation: The 38 year old man noticed slowly increasing swelling of his left knee joint after wakeboarding. Because of continuing discomfort 2 months later MRI diagnostic revealed, apart from retropatellar cartilage lesions, a popliteal mass compatible with a Baker cyst. The lesion of interest (later diagnosed as NF) was neither recognized by the radiologist nor the treating clinician. During the following 8 months the patient felt increasing swelling of the knee joint. The repeat MRI documented the crescent intraarticular solid synovial mass in the medial patellofemoral recess without signs of hemosiderin impregnation. A percutaneous sonographically guided 16G needle biopsy was performed. Histologically, bland myofibroblastic proliferation suggestive of nodular fasciitis (NF) was found. The next generation sequencing (NGS) demonstrated the presence of MYH9-USP6 gene fusion, confirming the diagnosis of NF. The lesion was excised under arthroscopic control. At 1 year follow-up the patient is asymptomatic. Conclusion: The case is of interest because of its rare pathology. The decision how to treat was based on pathologic biopsy diagnostics including the USP6-gene rearrangement. In view of similar presentation of the rare malignancies we also want to stress the importance of definitive diagnostics which generally are possible only through biopsy.

Osteofibrous Dysplasia-Like Adamantinoma of the Tibia Diagnosed at Age 6 Years Progressing into a Classic Adamantinoma over 39 Years, Reconstruction Performed by a Modified Capanna Technique: A Case Report

Background: It is generally accepted that there is a spectrum ranging from Osteofibrous Dysplasia (OFD) to Osteofibrous dysplasia-like Adamantinoma (OFD-AD) to “classic” Adamantinoma (AD). However, it is controversial whether OFD may progress into OFD-AD and AD or these pathologic changes reflect sampling issues. We herein report the fifth case of late development of AD from OFD-AD to underline the importance of long-term follow-up. Case: At 6 years bone biopsy of the tibia revealed the diagnosis of OFD-AD, confirmed by repeat biopsies until the age of 18 years. At age 45 years a progressive focal osteolysis was biopsied and showed histologically a classic AD. The affected tibial diaphysis was resected and pasteurized. Reconstruction was performed adapting the “Capanna technique” of inserting the ipsilateral mobilized fibula into the replanted autologous, pasteurized tibial segment as biologic stabilizer. At 1.5 years follow-up, the reconstruction has healed allowing full weight bearing.

Enchondromas of Long Bones and Other Skeletal Lesions Found Incidentally Need Critical Evaluation, But Rarely Systematic Follow-Up

Purpose: Incidental bone lesions are a challenge for the specialist, who has to give recommendations for further management. This review of our cases will assist in the decision whether the lesion can be “neglected”, needs further active follow-up or direct initiation of treatment. Patients and Methods: 153 cases of incidental bone findings were presented to our musculoskeletal tumor service for evaluation from July 2008 through June 2021. 73 of them were cartilaginous tumors and 63 of these were diagnosed as enchondroma of a long bone based on X-Ray and MRI. Results: Follow-up imaging of the enchondroma patients was available for 35 patients at 1 to 13 years (mean 4.3 y), with no change in size except for one femoral diaphyseal enchondroma with increasing diameter from age 18 to 20 years. 14 additional patients answered written contact stating that they remained asymptomatic at 2 to 12 years (mean 5.6 y). None of the patients has been reported to the Swiss Confoederation Cancer Registry to have developed malignancy. Among the 10 other cartilaginous tumors were one chondrosarcoma grade II exhibiting different imaging, 3 non-long-bone localizations (pelvis, scapula and rib), 2 Ollier-type enchondromas, and 2 osteochondromas. Incidental findings other than cartilaginous tumors were fibrous dysplasia (n = 31), non-ossifying fibroma (n = 31) and 18 other “sporadic” entities. Conclusions: Incidentally found enchondromas not exhibiting aggressive features need no systematic follow-up and patients can be “discharged” with the advice to present, if symptoms would develop. This also applies to fibrous dysplasia and the other sporadic lesions. 6 cases with other diagnoses needed specific treatment.

Osteotomy of the Margo Medialis Scapulae to Approach Subscapular and Subrhomboid Tumors. A Technical Note

Purpose: The approach to resect subscapular and subrhomboid tumors needs elevation of the scapula. This is usually performed by detaching the muscles from the margo medialis of the scapula. We wish to communicate our technique of a longitudinal osteotomy of the margo medialis for improved refixation of the muscles. Patients and Methods: 5 patients with subscapular and one patient with a subrhomboid benign tumor were operated on using this technique. Results: All patients achieved stable healing and full functional recovery;only in one patient there was slightly reduced elevation of the arm. Conclusion: Elevation of the muscles inserting into the medial scapular margo with a small rim of bone facilitates refixation and allows for excellent restitution of function.

Salvage of Failed Osteoarticular Tibia Allografts with Knee Arthroplasties

Background: Limb preservation in musculoskeletal tumor surgery has largely replaced amputation. Biologic reconstructions are now performed as preferred choice;if not feasible options are “megaprostheses”, allografts or composites. Endoprosthetic reconstructions usually provide immediate function, but fail at long term. Osteochondral allografts allow for one-to-one restoration and have potential for incorporation;however degeneration of the cartilage requiring revision almost inevitably will occur. In most cases, revision is then done by endoprosthetic replacement. Aim: In our patients, resurfacing of retained allografts failed. Problems encountered are presented and solutions proposed. Case Presentation: Resurfacing over retained allografts in the 2 index cases has resulted in failures related to fractures and instability. Revision with massive constrained endoprostheses was needed. Based on the experience with these failures, primary endoprosthetic replacement anchored in vital bone in a following case resulted in stable function. Conclusion: Knee replacement for advanced degeneration of the osteochondral allograft apparently needs choosing increased femoro-tibial constraint systems and stem extensions anchored to vital host bone.