Malignant Peripheral Nerve Sheath Tumors (MPNSTs) are rare tumors that often occur in patients with neurofibromatosis 1. Surgical resection represents the mainstay of treatment. Radiation and chemotherapy have a role in selected patients with MPNST. Accurate pathologic diagnosis remains a challenge in many cases of MPNST. There are many recent advances in the understanding of the molecular pathogenesis of MPNST which represent the best opportunities to develop new strategies for management of patients with MPNST.
Context:Intramuscular hemangiomas are common in the general population and often present at medical and surgical clinics. Unfortunately, unfamiliarity with these lesions has led to a high percentage of misdiagnoses, inappropriate workup, and unnecessary referrals.Evidence Acquisition:A literature search was performed using Medline, Embase, PubMed, and Cochrane. The relevant articles and referenced sources were reviewed for additional articles that discussed the epidemiology, pathophysiology, investigation, and management of intramuscular hemangiomas. Clinical experience from experts in orthopaedics, musculoskeletal pathology, and musculoskeletal radiology was compared. The selected case studies are shared cases of the authors.Results and Conclusion:The pathophysiology of these lesions is not completely understood, but much can be implied from their underlying vascular nature. Isolated lesions are benign tumors that never metastasize but tend to enlarge and then involute over time. Magnetic resonance imaging is the imaging modality of choice. If a systemic disorder or malignancy is not suspected or has been ruled out, conservative management is the treatment of choice for most intramuscular hemangiomas.
Hematomas in the extremities can present clinically as a soft tissue mass. Hematomas can usually be distinguished from neoplasia on MR by the signal patterns of hemoglobin breakdown products, which are dependent on the chemical bonding and oxidation state of hemoglobin iron. Beginning with a discussion of relevant atomic electronic structure, this review will examine how oxyhemoglobin, deoxyhemoglobin, methemoglobin, and hemosiderin, the principal iron compounds occurring in the various stages of a hematoma, affect its appearance on MRI.
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