Stereotactic body radiotherapy is a highly effective form of radiation therapy for palliation of bone metastases, but it can also lead to rare but severe side effects, such as myonecrosis. According to the literature, the incidence of myonecrosis after stereotactic body radiotherapy is low and mostly dose dependent. It is crucial to consider the potential impact of immunotherapy and other systemic therapies in the assessment. The course of radiation myonecrosis can vary, and corticosteroids or vascular endothelial growth factor inhibitors may potentially play a role in its treatment. Herein, we report two patients presenting with myonecrosis after stereotactic body radiotherapy for bone metastasis.

The genus Clostridium is an important group of pathogenic and nonpathogenic Gram-positive anaerobic bacteria with a sporulation capacity and wide distribution in different environments, including the gastrointestinal tracts of healthy and diseased animals and humans. Among the pathogenic species of the genus, Clostridium chauvoei stands out as a histotoxic agent. It causes significant myonecrosis such as blackleg, a disease with high lethality, especially in young cattle, and is responsible for significant livestock losses worldwide. The pathogenicity of the disease is complex and has not yet been fully elucidated. Current hypotheses cover processes from the initial absorption to the transport and deposition of the agent in the affected tissues. The virulence factors of C. chauvoei have been divided into somatic and flagellar antigens and soluble antigens/toxins, which are the main antigens used in vaccines against blackleg in Brazil and worldwide. This review provides important information on the first and current approaches to the agent C. chauvoei and its virulence factors as well as a compilation of data on Brazilian studies related to blackleg.

Skeletal muscle necrosis is a common clinical manifestation of snakebite envenoming. The predominant myotoxic components in snake venoms are catalytically-active phospholipases A2 (PLA2) and PLA2 homologs devoid of enzymatic activity, which have been used as models to investigate various aspects of muscle degeneration. This review addresses the changes in the contractile apparatus of skeletal muscle induced by these toxins. Myotoxic components initially disrupt the integrity of sarcolemma, generating a calcium influx that causes various degenerative events, including hypercontraction of myofilaments. There is removal of specific sarcomeric proteins, owing to the hydrolytic action of muscle calpains and proteinases from invading inflammatory cells, causing an initial redistribution followed by widespread degradation of myofibrillar material. Experiments using skinned cardiomyocytes and skeletal muscle fibers show that these myotoxins do not directly affect the contractile apparatus, implying that hypercontraction is due to cytosolic calcium increase secondary to sarcolemmal damage. Such drastic hypercontraction may contribute to muscle damage by generating mechanical stress and further sarcolemmal damage.

This review illustrates the imaging features of rhabdomyolysis across multiple modalities and in a variety of clinical scenarios. Rhabdomyolysis is the rapid breakdown of striated muscle following severe or prolonged insult resulting in the release of myocyte constituents into circulation. In turn, patients develop characteristically elevated serum creatine kinase, positive urine myoglobin, and other serum and urine laboratory derangements. While there is a spectrum of clinical symptoms, the classic presentation has been described as muscular pain, weakness, and dark urine. This triad, however, is only seen in about 10% of patients. Thus, when there is a high clinical suspicion, imaging can be valuable in evaluating the extent of muscular involvement, subsequent complications such as myonecrosis and muscular atrophy, and other etiologies or concurrent injuries causing musculoskeletal swelling and pain, especially in the setting of trauma. Sequela of rhabdomyolysis can be limb or life-threatening including compartment syndrome, renal failure, and disseminated intravascular coagulation. MRI, CT, ultrasound, and 18-FDG PET/CT are useful modalities in the evaluation of rhabdomyolysis.

There are many microvascular and macrovascular complications regarding uncontrolled diabetes mellitus (DM). Among them, diabetes myonecrosis is one of the complications but rarely seen in the uncontrolled DM patient population. Here, we present a rare case of DM myonecrosis in a patient with elevated hemoglobin A1c (HbA1c) of 18.2% and discuss the literature review of diabetes myonecrosis. A 48-year-old male with hypertension and uncontrolled type 2 diabetes mellitus (T2DM) with hemoglobin A1c of 18.2% presented with progressive swelling and pain in the right thigh for two days. Physical examination demonstrated swollen and tense tender right thigh with a circumference five inches larger than the left. Computed tomography (CT) and magnetic resonance imaging (MRI) results revealed severe myositis of the right leg, likely myonecrosis, and associated fascial edema/fasciitis. The patient was also complicated with diffuse anasarca, which was corrected with albumin transfusion and furosemide. Aspirin and lisinopril were also started for antithrombotic and cardioprotective effects. The right thigh swelling improved, and the patient could ambulate with supportive measures and regular physical therapy (PT). He was discharged home after 45 days of hospitalization. Diabetic myonecrosis is a rare condition and hence is underdiagnosed. In patients with uncontrolled diabetes, especially with diabetic complications, physicians should have high clinical suspicion to diagnose diabetic myonecrosis when patients present with an acute unilateral painful swollen limb. Our case highlights the complicated course of diabetes myonecrosis with anasarca, improved with supportive measures.

Muscle necrosis is a potential clinical complication of snakebite envenomings, which in severe cases can lead to functional or physical sequelae such as disability or amputation. Snake venom proteins with the ability to directly damage skeletal muscle fibers are collectively referred to as myotoxins, and include three main types: cytolysins of the \"three-finger toxin\" protein family expressed in many elapid venoms, the so-called \"small\" myotoxins found in a number of rattlesnake venoms, and the widespread secreted phospholipase A2 (sPLA2) molecules. Among the latter, protein variants that conserve the sPLA2 structure, but lack such enzymatic activity, have been increasingly found in the venoms of many viperid species. Intriguingly, these sPLA2-like proteins are able to induce muscle necrosis by a mechanism independent of phospholipid hydrolysis. They are commonly referred to as \"Lys49 myotoxins\" since they most often present, among other substitutions, the replacement of the otherwise invariant residue Asp49 of sPLA2s by Lys. This work comprehensively reviews the historical developments and current knowledge towards deciphering the mechanism of action of Lys49 sPLA2-like myotoxins, and points out main gaps to be filled for a better understanding of these multifaceted snake venom proteins, to hopefully lead to improved treatments for snakebites.

BACKGROUND: Clostridium species are known to be the primary causative organism of gas gangrene. Non-clostridial gas gangrene (NCGG) is another rare necrotizing entity often associated with an underlying disease, particularly diabetes mellitus, and has a high mortality rate.
METHODS: A 16-year-old, immunocompetent male was referred to us after four days, following a roadside accident, with a degloving injury over the thigh and knee along with fractures around the knee. Although clinico-radiologically suspicious of gas gangrene, the initial smear report was negative for any Gram-positive bacilli. On the same day, he underwent aggressive debridement with an external fixator spanning the knee to salvage the limb. On post-operative day one, due to deteriorating general clinical condition and a strong clinical suspicion of gas gangrene, he underwent above-knee amputation (open stump) after discussion with microbiologists and physicians.
RESULTS: Polymicrobial non-clostridial infection was seen in culture reports taken serially at different stages of management. The latest follow-up showed a healed amputation stump following split skin grafting.
CONCLUSIONS: Although rare, polymicrobial infections can present as non-clostridial gas gangrene even in an immunocompetent patient. A high index of clinical suspicion with a multi-disciplinary approach helps in early decision-making to avoid a devastating outcome.

Bothrops snakebite treatment is antivenom therapy, which is ineffective in neutralizing the severe local effects caused by these envenomations. There are evidence that photobiomodulation therapy (PBMT) has emerged as a promising tool to counteract the venom-induced local effects. The purpose was to write a narrative review of the literature about PBMT as a treatment for Bothrops snakebites. We reviewed articles indexed in PubMed, SCOPUS and Scientif Direct database with filter application. Included studies had to investigate local effects induced by Bothrops snake venom in any animal model using any type of photobiomodulation irradiation and at least one quantitative measure of local effects of Bothrops envenomation. Sixteen studies were selected from 54 original articles targeted PBMT (low-level laser or light emitting diode) as a complementary tool for local effects treatment induced by snakebites, and all its assessments. Articles were critically assessed by two independent raters with a structured tool for rating the research quality. PBMT demonstrate to be a promising tool for local treatment effects caused by snakebite by reducing local edema, hyperalgesia, leukocyte influx and myonecrosis and accelerating tissue regeneration related to myotoxicity. However, the mechanism is not well understood and additional studies are needed.

Pyomyositis is an uncommon primary bacterial infection of skeletal muscles, usually caused by Staphylococcus aureus. Predisposing factors for pyomyositis include immunodeficiency, trauma, injection drug use, concurrent infection and malnutrition. The diagnosis, staging of the disease and differential diagnosis are established by ultrasound, CT and MRI. Treatment involves surgical drainage and antibiotic therapy. We report a case of abdominal rectus muscle pyomyositis, which constitutes, as far as we know, the second reported in bibliography, while Prevotella disiens is firstly reported as causative agent.

Elevation of pressure within tightly bound myofascial compartments has detrimental consequences if not treated promptly, leading to a loss of circulation, ischemia, myonecrosis, nerve damage, and limb loss. They are commonly seen in the distal upper and lower extremities; however, compartment syndrome of the hand is rarely encountered and prompt recognition can prevent permanent damage and tissue loss. This case study presents a complicated case of compartment syndrome of the hand and discusses the interrelationship between compartment syndrome and rhabdomyolysis. An emphasis is placed on pathophysiology of this relationship to allow a better understanding of the imaging features as well as early clinical recognition of compartment syndrome. Magnetic resonance imaging findings are specifically discussed as it remains the best imaging tool to evaluate the extent of the damage and surgical planning.