Pearls and Pitfalls for Soft-Tissue and Bone Biopsies: A Cross-Institutional Review.

Management of soft-tissue and bone neoplasms depends on a definitive histologic diagnosis. Percutaneous image-guided biopsy of bone and soft-tissue tumors is a cost-effective and accurate method to obtain a histopathologic diagnosis. Biopsy requests must be approached thoughtfully to avoid numerous potential pitfalls. Hasty biopsy planning places the patient at increased risk for misdiagnosis, delayed therapy, repeated invasive procedures, and substantial morbidity. Biopsy planning begins with a thorough review of the relevant clinical history and pertinent imaging. The biopsy route must be planned in concert with the referring orthopedic oncologist to preserve limb-sparing options. Carefully selecting the most appropriate imaging modality to guide the biopsy increases the chances of reaching a definitive diagnosis. It is also critical to identify and target with expertise the part of the lesion that is most likely to yield an accurate diagnosis. Percutaneous biopsy is a safe procedure, and familiarity with preprocedural laboratory testing parameters, anticoagulation guidelines, and commonly used sedation medications minimizes the risk of complications while ensuring patient comfort. Nondiagnostic biopsy results are not infrequent and may still have value in guiding patient treatment. Awareness of the imaging manifestations of tumor recurrence is also important. The aim of this article is to provide a comprehensive review of pertinent preprocedural, periprocedural, and postprocedural considerations for bone and soft-tissue musculoskeletal biopsies.The online slide presentation from the RSNA Annual Meeting is available for this article.©RSNA, 2020.

Locally aggressive and multifocal phosphaturic mesenchymal tumors: two unusual cases of tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) has long been recognized as a clinical paraneoplastic syndrome. The identification of a unique histopathologic entity, the phosphaturic mesenchymal tumor (PMT), as a distinct etiology for TIO has been a more recent discovery. The majority of published cases describe a solitary, non-aggressive appearing soft tissue or osseous lesions in patients with osteomalacia; aggressive appearing or multifocal lesions appear to be exceedingly rare. These tumors characteristically secrete fibroblast growth factor 23 (FGF23). Elevated serum levels of FGF23 result in phosphate wasting and osteomalacia. In the majority of cases, laboratory abnormalities and clinical signs and symptoms of osteomalacia precede identification of the causative lesion by years. Following diagnosis, complete resection with wide margins to prevent local recurrence is most often curative. Imaging characteristics of PMT are diverse and remain incompletely defined, as the majority of previous publications are outside of the radiologic literature. We present multiple imaging modalities in two cases of patients with debilitating osteomalacia and unusual appearing PMTs: one with a locally aggressive lesion leading to pathologic fracture, the second presenting with exceedingly rare multifocal PMT.

Fasciitis in amyopathic dermatomyositis.

Dermatomyositis is a disease frequently treated by rheumatologists and dermatologists due to prominent systemic features of inflammatory myositis, less common arthritis, and rare systemic vasculitis, in addition to the characteristic cutaneous manifestations of Gottron's papules over extensor surfaces, and a heliotrope rash over the eyelids. Patients with amyopathic dermatomyositis, a subset of dermatomyositis, display skin disease but no apparent muscle disease. This report describes an adult patient with the typical dermatomyositis rash with no weakness, normal muscle enzymes, and the unique finding of fasciitis without myositis on muscle biopsy, which correlated with a Magnetic Resonance Imaging (MRI) finding of a peripheral halo of intense signal around muscles on T2-weighted and fat suppression sequences. Although MRI finding of presumed fasciitis has been reported in juvenile-onset dermatomyositis, this is the first report of MRI evidence of fasciitis with pathological correlation in adult-onset dermatomyositis. We suggest that if MRI scans are ordered, as part of the work-up of dermatomyositis, a peripheral halo of increased signal should specifically be looked for, which could be interpreted as fasciitis based on this case report.