Acute pyomyositis of the pelvis: the spectrum of clinical presentations and MR findings

Optimizing Advanced Imaging of the Pediatric Patient in the Emergency Department: Technical Report

Advanced diagnostic imaging modalities, including ultrasonography, computed tomography, and magnetic resonance imaging, are key components in the evaluation and management of pediatric patients presenting to the emergency department. Advances in imaging technology have led to the availability of faster and more accurate tools to improve patient care. Notwithstanding these advances, it is important for physicians, physician assistants, and nurse practitioners to understand the risks and limitations associated with advanced imaging in children and to limit imaging studies that are considered low value, when possible. This technical report provides a summary of imaging strategies for specific conditions where advanced imaging is commonly considered in the emergency department. As an accompaniment to the policy statement, this document provides resources and strategies to optimize advanced imaging, including clinical decision support mechanisms, teleradiology, shared decision-making, and rationale for deferred imaging for patients who will be transferred for definitive care.

Optimizing Advanced Imaging of the Pediatric Patient in the Emergency Department: Technical Report

Advanced diagnostic imaging modalities, including ultrasonography, computed tomography, and magnetic resonance imaging (MRI), are key components in the evaluation and management of pediatric patients presenting to the emergency department. Advances in imaging technology have led to the availability of faster and more accurate tools to improve patient care. Notwithstanding these advances, it is important for physicians, physician assistants, and nurse practitioners to understand the risks and limitations associated with advanced imaging in children and to limit imaging studies that are considered low value, when possible. This technical report provides a summary of imaging strategies for specific conditions where advanced imaging is commonly considered in the emergency department. As an accompaniment to the policy statement, this document provides resources and strategies to optimize advanced imaging, including clinical decision support mechanisms, teleradiology, shared decision-making, and rationale for deferred imaging for patients who will be transferred for definitive care.

Case report: A case of piriformis pyomyositis and pyogenic sacroiliitis due to non-typhoidal Salmonella bacteremia in an immunocompetent healthy adult

Non-typhoidal Salmonella (NTS) rarely causes bacteremia and subsequent focal infections as an extraintestinal complication, even in immunocompetent adults. A 25-year-old man was hospitalized for several days with difficulty moving due to fever, acute buttock pain, and shivering. He had no recent or current respiratory symptoms and no clear gastrointestinal symptoms. Physical examination revealed mild redness around the left buttock and difficulty raising the left lower extremity due to pain, in addition to which blood tests showed high levels of inflammatory markers. His clinical course and laboratory findings suggested sepsis, and magnetic resonance imaging revealed a high-intensity area in the left piriformis muscle on diffusion-weighted imaging; therefore, acute piriformis pyomyositis was strongly suggested. Cephazolin was started upon hospitalization; however, blood and stool cultures proved positive for NTS, and the antibiotics were changed to ceftriaxone. Follow-up MRI showed a signal in the left piriformis muscle and newly developed left pyogenic sacroiliitis. On the 25th hospital day, a colonoscopy was performed to identify the portal of entry for bacteremia, which revealed a longitudinal ulcer in the sigmoid colon in the healing process. His buttock pain gradually improved, and the antibiotics were switched to oral levofloxacin, which enabled him to continue treatment in an outpatient setting. Finally, the patient completed seven weeks of antimicrobial therapy and returned to daily life without leaving any residual disability. Invasive NTS infection due to bacteremia is rare among immunocompetent adults. Piriformis pyomyositis and subsequent pyogenic sacroiliitis should be added to the differential diagnosis of acute febrile buttock pain. In the case of NTS bacteremia, the entry site must be identified for source control. Additionally, the background of the host, especially in such an immunocompetent case, needs to be clarified; therefore, the patient should be closely examined.

Pelvic Pyomyositis in Childhood: Clinical and Radiological Findings in a Tertiary Pediatric Center

Pyomyositis (PM) is an infrequent but increasing bacterial infection of the skeletal muscle, with muscles of the pelvis and thigh frequently involved. The diagnosis is often challenging, especially when a deep muscle is affected. We present a single-center pediatric cohort affected by pelvic PM. A retrospective analysis was performed, including children admitted to Meyer Children’s Hospital between 2010 and 2020. Demographic, anamnestic, clinical, laboratory, radiological and management data were collected. Forty-seven patients (range 8 days–16.5 years, 66% males) were selected. Pain (64%), functional limitations (40%) and fever (38%) were the most common presenting symptoms; 11% developed sepsis. The median time to reach the diagnosis was 5 days (IQR 3–9). Staphylococcus aureus was the most common organism (30%), Methicillin-Resistant S aureus (MRSA) in 14%. PM was associated with osteomyelitis (17%), arthritis (19%) or both (45%). The infection was multifocal in 87% of children and determined abscesses in 44% (40% multiple). Pelvic MRI scan, including diffusion-weighted imaging (DWI), always showed abnormalities when performed. Clinical and laboratory findings in pelvic PM are unspecific, especially in infancy. Nevertheless, the infection may be severe, and the suspicion should be higher. MRI is the most useful radiological technique, and DWI sequence could reveal insidious infections.

Pseudomonas aeruginosa Pyomyositis in a Child With Acute Lymphoblastic Leukemia: A Case Report and Review of Literature

BACKGROUND

We report the case of an 11-year-old girl with a recent diagnosis of common B-cell acute lymphoblastic leukemia who presented with Pseudomonas aeruginosa pyomyositis of the left lower limb during severe neutropenia associated with the induction phase of chemotherapy.

OBSERVATIONS

Presenting signs included fever, leg pain, and refusal to walk. Popliteal knee ultrasonography was unremarkable, whereas magnetic resonance imaging showed 2 intramuscular fluid collections requiring surgically drainage.

CONCLUSION

A review of medical literature showed that pyomyositis is an infrequent complication in children with hematological malignancies, and most cases are due to Staphylococcus aureus, whereas Pseudomonas aeruginosa appears to be rarely involved.

Purulent infectious myositis (formerly tropical pyomyositis)

Purulent infectious myositis (PIM), formerly known as tropical pyomyositis, is a pyogenic infection of skeletal muscles. Staphylococcus aureus, a normal human skin inhabitant, is the main pathogen involved, but multiple other microorganisms have been implicated. Although usually a progressive febrile disease with pain in the affected muscle(s), severe, life-threatening forms have been described, especially in immunosuppressed patients and children. PIM may elude early diagnosis given the lack of overlying skin changes. Hence, high index of suspicion followed by imaging modalities (ultrasonography when superficial and computed tomography or magnetic resonance imaging with contrast when deep) help confirm the diagnosis. Treatment requires combination of percutaneous or open surgical drainage along with antimicrobial therapy guided by culture results. The rising incidence of cases due to methicillin-resistant Staphylococcus aureus (MRSA) strains, makes the inclusion of vancomycin be recommended. This paper reviews PIM highlighting its global distribution, causative agents, predisposing factors, management, and potential complications.

Quality Improvement of Magnetic Resonance Imaging for Musculoskeletal Infection in Children Results in Decreased Scan Duration and Decreased Contrast Use

BACKGROUND

Magnetic resonance imaging (MRI) is a heavily utilized resource to evaluate children suspected to have a musculoskeletal infection. Complex interdisciplinary workflows are involved with decision-making with regard to indications, anesthesia, contrast use, and procedural timing relative to the scan. This study assesses the impact of a quality improvement endeavor on MRI workflows at a tertiary pediatric medical center.

METHODS

A registry of consecutively enrolled children for a multidisciplinary musculoskeletal infection program identified those evaluated with MRI from 2012 to 2018. Annual MRI process improvement feedback was provided to the key stakeholders. Demographic characteristics, laboratory parameters, MRI indications, anesthesia use, MRI findings, final diagnoses, scan duration, imaging protocol, surgical intervention following MRI, and length of stay were retrospectively compared between the 3 cohorts (initial, middle, and final) representing 2-year increments to assess the impact of the initiative.

RESULTS

There were 526 original MRI scans performed to evaluate 1,845 children with suspected musculoskeletal infection. Anesthesia was used in 401 children (76.2%). When comparing the initial, middle, and final study period cohorts, significant improvement was demonstrated for the number of sequences per scan (7.5 sequences for the initial cohort, 5.8 sequences for the middle cohort, and 4.6 sequences for the final cohort; p < 0.00001), scan duration (73.6 minutes for the initial cohort, 52.1 minutes for the middle cohort, and 34.9 minutes for the final cohort; p < 0.00001), anesthesia duration (94.1 minutes for the initial cohort, 68.9 minutes for the middle cohort, and 53.2 minutes for the final cohort; p < 0.00001), and the rate of contrast use (87.6% for the initial cohort, 67.7% for the middle cohort, and 26.3% for the final cohort; p < 0.00001). There was also a trend toward a higher rate of procedures under continued anesthesia immediately following the MRI (70.2% in the initial cohort, 77.8% in the middle cohort, and 84.6% in the final cohort). During the final 6-month period, the mean scan duration was 24.4 minutes, anesthesia duration was 40.9 minutes, and the rate of contrast administration was 8.5%.

CONCLUSIONS

Progressive quality improvement through collaborative interdisciplinary communication and workflow redesign led to improved utilization of MRI and minimized contrast use for suspected musculoskeletal infection. There was a high rate of procedural intervention under continued anesthesia for children with confirmed musculoskeletal infection.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tales from the Night:: Emergency MR Imaging in Pediatric Patients after Hours

Overnight in-house radiology has rapidly become an important part of contemporary practice models, and is increasingly the norm in pediatric radiology. MR imaging is an indispensable first-line and problem-solving tool in the pediatric population. This has led to increasingly complex MR imaging being performed "after hours" on pediatric patients. This article reviews the factors that have led to widespread overnight subspecialty radiology and the associated challenges for overnight radiologists, and provides an overview of up-to-date imaging techniques and imaging findings of the most common indications for emergent MR imaging in the pediatric population.

ACR Appropriateness Criteria® Acutely Limping Child Up To Age 5

Imaging plays in important role in the evaluation of the acutely limping child. The decision-making process about initial imaging must consider the level of suspicion for infection and whether symptoms can be localized. The appropriateness of specific imaging examinations in the acutely limping child to age 5 years is discussed with attention in each clinical scenario to the role of radiography, ultrasound, nuclear medicine, computed tomography, and magnetic resonance imaging. Common causes of limping such as toddler's fracture, septic arthritis, transient synovitis, and osteomyelitis are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Abdominal rectus muscle pyomyositis: Report of a case and review of the literature

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.

JOURNAL CLUB: Can Coronal STIR Be Used as Screening for Acute Nontraumatic Hip Pain in Children?

OBJECTIVE

The objective of this study is to evaluate whether coronal STIR MRI can be used as a screening test for nontraumatic acute hip pain in children.

MATERIALS AND METHODS

From 2008 to 2012, we identified all patients younger than 18 years at our tertiary care facility who underwent pelvic MRI including coronal STIR for the following indications: acute hip pain, limping, or refusal to bear weight. Patients with a history of trauma were excluded. Each MR image was independently reviewed by four radiologists who were blinded to the clinical outcome. After first reviewing the coronal STIR images only, they then reviewed the full MRI studies in a random order different from that used for review of the coronal STIR images. The sensitivity and specificity of STIR-only images in identifying the presence of abnormality and specific diagnoses were calculated, with the full MRI study considered as the reference standard. Kappa values were calculated for STIR-only and full MRI studies.

RESULTS

A total of 127 patients (67 female patients and 60 male patients; median age, 9 years; range, 5 months to 17 years) were identified. The most common abnormalities (calculated as the mean of frequency values noted by four readers) were hip effusion (52%; range, 46-58%), osteomyelitis (42%; range, 29-48%), and myositis (32%; range, 20-40%). For the detection of any abnormality, STIR-only images had a mean sensitivity of 95% and a mean specificity of 67%. For approximately one-third of STIR-only studies with true-positive results, additional abnormalities were found on full MRI studies.

CONCLUSION

Coronal STIR imaging of the pelvis has high sensitivity (95%) in the detection of abnormalities associated with acute nontraumatic hip pain in children, but it often misses additional abnormalities.

Pediatric pelvic pyomyositis: initial MRI can be misleading

Pelvic pyomyositis is an infection of the skeletal muscles around the hip joint. Fever, hip pain, limp, and leukocytosis are common; however, the clinical picture is often vague. MRI is the current gold-standard imaging for pyomyositis. No studies in the current literature have reported an unremarkable initial MRI in a patient with symptomatic pyomyositis. An adolescent female presented with symptomatic pelvic pyomyositis, but admission MRI was normal. A follow-up MRI indicated development of pelvic pyomyositis. The patient was successfully managed nonoperatively. The initial MRI in pyomyositis can be misleading. Patients should be admitted and MRI should be repeated, as indicated clinically.

Key role of magnetic resonance imaging in the diagnosis of infections around the hip and pelvic girdle mimicking septic arthritis of the hip in children

Infections around the hip and the pelvic girdle mimicking septic hip arthritis are rare conditions in the pediatric population requiring urgent treatment. They are not readily diagnosed because of rarity, resemblance to septic hip, and unclear pathophysiology, which often results in misdiagnosis, delayed diagnosis, and delayed treatment. The aim of this study was to prove the key role of magnetic resonance imaging (MRI) as the first-line modality in making a early definite diagnosis of an uncommon perihip infection in children. We retrospectively reviewed 20 children with a provisional diagnosis of unilateral septic hip who were confirmed finally to have perihip infections and combined with concomitant osteomyeltis using MRI. All patients were treated with intravenous antibiotics with or without abscess aspiration until normalization of clinical symptoms and laboratory tests including serum C-reactive protein and erythrocyte sedimentation rate. All infections healed successfully and the final C-reactive protein was recovered to a mean of 0.37 mg/dl (range 0.01-0.78 mg/dl) without recurrence or complication. Although the MRI is costly and limited in practical application, it was found to be effective as a primary diagnostic tool for an early, accurate diagnosis of infections around the hip and the pelvic girdle in children to correctly guide the decision and the approach for treatment.

Improved Magnetic Resonance Imaging Utilization for Children with Musculoskeletal Infection

BACKGROUND

Magnetic resonance imaging (MRI) with sedation is an important resource used to evaluate children with musculoskeletal infection. This study assesses the impact of multidisciplinary guidelines and continuous process improvement on MRI utilization at a tertiary pediatric medical center.

METHODS

A multidisciplinary team developed a guideline for MRI with sedation, and it was implemented at our institution. Scan duration, anatomic regions imaged, sequences performed, timing of surgical intervention, length of hospital stay, and readmissions for these children were compared with these measures among a cohort of similar children who had been treated prior to guideline implementation. Comparative data were gathered for the subsequent cohort to determine any impact of the continued process improvement program on MRI utilization. Statistical comparison was performed to determine significant differences between groups.

RESULTS

Children evaluated prior to the guideline implementation had 9.0 MRI sequences per scan, an MRI scan duration of 111.6 minutes, and a hospital stay of 7.5 days. In comparison, children in the initial MRI guideline cohort had 7.5 sequences per scan, a scan duration of 76.1 minutes, and a hospital stay of 5.4 days. Children in the subsequent guideline cohort had 6.5 sequences per scan, a scan duration of 56.3 minutes, and a hospital stay of 5.0 days. The rate of immediate surgical procedure under continued anesthesia was 16.7% prior to the guideline, 50.5% among children in the initial guideline cohort, and 64% among children in the subsequent guideline cohort. Differences between cohorts were significant (p < 0.0001). In aggregate, 264 hours of MRI scan time and 809 hospital bed-days were conserved for more than thirty months.

CONCLUSIONS

This initiative promoted improvement in diagnostic efficiency, therapeutic consistency, and patient safety for children with musculoskeletal infection.

CLINICAL RELEVANCE

The findings of this study illustrate the beneficial impact of interdisciplinary coordination of care on clinical outcomes for children with musculoskeletal infection. Tangible improvements occurred for both length of stay and resource utilization.

Pyomyositis Causing Temporary Quadriparesis During Induction Therapy for Acute Lymphoblastic Leukemia: Case Report and Review of the Literature

Pyomyositis (PM) is a purulent infection of skeletal muscle. It is often associated with immunosuppression in temperate climates. Herein, we report a case of PM causing temporary quadriparesis in a 14-year-old girl undergoing induction therapy for acute lymphoblastic leukemia and we review the reported pediatric cases associated with induction therapy for hematologic malignancies. Early symptoms of PM can be mistaken for the side effects of chemotherapeutic agents. Greater awareness of the clinical picture of PM will aid in early diagnosis and treatment. With appropriate medical therapy and timely abscess drainage, morbidity and mortality is greatly reduced.

Lower extremities and iliopsoas pyomyositis with concurrent septic arthritis and spinal epidural abscess in a diabetic patient

Pyomyositis is a rarely encountered infection among diabetics, which usually affects lower extremities. Herein, we present a case of lower extremities and iliopsoas pyomyositis with concurrent septic arthritis and spinal epidural abscess in a patient with poorly controlled diabetes mellitus.

Primary pyomyositis of the pelvis in children: a retrospective review of 8 cases

Primary pyomyositis of the pelvic musculature is a condition rarely seen in temperate climates, although its frequency has been increasing in the United States. The condition should be considered in the initial differential diagnosis of an adolescent presenting with fever, difficulty ambulating, and hip pain. This is a retrospective review of 8 cases of primary pelvic pyomyositis in patients aged 18 years or younger who were treated at the Children's Medical Center in Augusta, Georgia. The site of infection was the obturator internus in the majority of the cases (5). The site was the gluteus, iliopsoas, and iliacus in 1 case each. Four patients who were diagnosed early responded to intravenous antibiotics with no need for further intervention. Two patients required incision and drainage of an abscess combined with antibiotics. Two patients had prolonged hospital courses requiring intensive unit care and mechanical ventilation. Blood cultures were positive in 87.5% of patients, and all patients presented with elevated acute phase reactants. One of the most difficult diagnostic aspects of presentation is an inconclusive symptom profile. It is noteworthy that patients with pelvic pyomyositis may present with limited range of motion in a specific plane (the motion placing the infected muscle on stretch) vs global limited range of motion of the joint as is commonly seen in septic arthritis. Early diagnosis is essential to prevent systemic illness and complications associated with this condition. Magnetic resonance imaging with gadolinium is helpful to diagnose and guide treatment.

The conservative management of primary pyomyositis abscess in children: case series and review of the literature

Pyomyositis is a primary pyogenic infection in skeletal muscle, often progressing to abscess formation. It is rare in temperate climates and generally deep-seated within the pelvis with nonspecific clinical features, making diagnosis difficult. Magnetic resonance imaging (MRI) is highly sensitive for muscle inflammation and fluid collection, and with its increasing availability is now the investigation of choice. Treatment of pyomyositis abscess has traditionally been with incision and drainage or guided aspiration followed by a prolonged course of antibiotics, although there are sporadic reports of cases treated successfully with antibiotics alone. Our aim was to describe our own experience with the treatment of pyomyositis abscess in children. From our 20-year database of over 16,000 paediatric orthopaedic admissions, we identified only three cases with MRI-confirmed pyomyositis abscess. These were all in boys (aged 2-12 years) and affected the gluteal, piriformis and adductor muscles. Despite the organisms not being identified, each patient was treated successfully with a short (4-7 days) course of intravenous antibiotics followed by 2-6 weeks of oral therapy. There were no recurrences or complications and all made a full recovery. In conclusion, we propose that uncomplicated pyomyositis abscess in children may usually be managed conservatively without the need for open or percutaneous drainage.

Imaging on pelvic pyomyositis in children related to pathogenesis

PURPOSE

Pelvic pyomyositis in children is a rare infectious condition, although it is increasingly reported in temperate climates. Often considered a primary disease, new diagnostic methods are able to identify additional foci of infection. The purpose of this study is to review our patients and to analyze the imaging studies to determine its pathogenesis.

METHODS

A retrospective study of the clinical charts and imaging records of 11 patients was made, noting the number and location of muscles involved, as well as bone and joint involvement.

RESULTS

Besides the classical form of pelvic pyomyositis, i.e., iliopsoas pyomyositis, other muscular groups were frequently affected, often with multiple involvement. Bone involvement is also frequent. Magnetic resonance imaging (MRI) gives the most useful information.

CONCLUSION

MRI is the diagnostic procedure of choice for diagnosing pelvic pyomyositis in children. It may also have an elucidating role in the debated pathogenesis of this condition. In most of the cases, pelvic pyomyositis in children could be secondary.

Magnetic resonance imaging findings in hematogenous osteomyelitis of the hip in adults

Hematogenous hip infections are rare in adults and the extent of infection into the bone or adjacent soft tissues may be underestimated, leading to inadequate surgical débridement. Using MRI, we sought to determine the extent of bone involvement and the presence of adjacent soft tissue abscesses in adults with hip osteomyelitis. We reviewed the records and MRIs in 11 adult patients (12 hips) with hematogenous osteomyelitis of the femoral head in 12 hips. Ten of 11 patients had one or more comorbidities. All patients underwent surgical débridement and received antibiotic therapy for 6 weeks. MRI revealed osteomyelitis distal to the femoral head in seven of 12 hips with extension into the medullary canal in three of these seven. Femoral head erosions were present in 10 hips, acetabulum osteomyelitis in 11, and acetabular erosions in six hips. Infection extended into adjacent soft tissues in eight of 12 hips. MRI demonstrated that the infection may extend distal to the femoral head or into the adjacent soft tissues. MRI may be useful for preoperative planning so that all regions affected by the infection can be treated.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Tropical primary pyomyositis in children of the UK: an emerging medical challenge

Pyomyositis is a commonly encountered condition in the tropics. It was not described in the UK until 1998. The reason for the increasing incidence is not understood. We sought to identify the experience gained of this condition within a UK paediatric tertiary referral unit. Retrospective review of cases of pyomyositis from our institution since 1998 was undertaken to identify demographics, presentation, diagnosis and management. Thirteen cases were identified. The obturator internus was most commonly affected (62%). Staphylococcus aureus was cultured in nine cases (69%). One diagnostic retroperitoneal exploration was performed and all cases were identified by computed tomography or magnetic resonance imaging. To our knowledge, this is the first UK series of pyomyositis, reflecting its increasing Western incidence. Early diagnosis and treatment with antibiotics is all that is needed in the majority of cases. A greater awareness of this emerging condition is necessary to prevent misdiagnosis and unnecessary surgical intervention by all surgeons.

Staphylococcus aureus: a community pathogen

Staphylococcus aureus is a common human pathogen. S aureus infections most commonly clinically manifest as skin infections. There has been much interest in S aureus infections in the community over the past decade because of the rise of community-associated methicillin-resistant S aureus (CA-MRSA) infections, which have emerged globally over a relatively short period of time. In contrast to health care-associated methicillin resistant S aureus (HA-MRSA), circulating strains of CA-MRSA have characteristic pathogenesis, strain characteristics, epidemiology, and clinical manifestations that are distinct from HA-MRSA. In fact, CA-MRSA probably behaves more like community-associated methicillin-sensitive S aureus (MSSA). This article reviews current knowledge of the epidemiology and clinical manifestations of community-associated S aureus and CA-MRSA infections.

Pyomyositis of the iliacus muscle complicated with septic sacroiliitis

We report a rare case of pyomyositis of the iliacus muscle in a 29-year-old woman. After 2 weeks of adequate treatment, secondary septic sacroiliitis occurred, a complication that had not been described previously. Pyomyositis of the iliacus muscle must be considered in the differential diagnosis of acute pain in the hip region.

Benign acute childhood myositis: an unusual cause of calf pain

We present a 17-year-old boy with benign acute childhood myositis (BACM) who presented with acute onset of right calf pain, swelling, and difficulty walking. The MR findings are reviewed. MR may be useful in diagnosing BACM and in differentiating it from other causes of myositis.

MRI for Detection of Abscess in Acute Osteomyelitis of the Pelvis in Children

OBJECTIVE

We analyzed our experience with MRI of pelvic acute hematogenous osteomyelitis (AHO) to address the following questions: What does MRI reveal about bone involvement? How often are fluid collections indicative of abscess shown? Are clinical parameters predictive of the cases in which MRI would be more beneficial?

MATERIALS AND METHODS

We retrospectively reviewed the imaging studies and medical records from the past 5 years of 38 children ranging in age from 25 to 211 months who were diagnosed with pelvic osteomyelitis using MRI. Statistical analysis of demographic and clinical variables was compared between patients with an abscess (n = 21) and those without (n = 17) who were identified on MRI.

RESULTS

Osteomyelitis involved metaphyseal equivalent sites in every case (n = 38), with single bone involvement in 24 (63%) and contiguous bone involvement in the remaining 14 (37%). Fluid collections indicative of an abscess were seen in 21 cases (55%), and abscess drainage was performed in 10 (26%). Univariate analysis of demographic and clinical variables between patients with and without an abscess indicated no significant differences for any variable except erythrocyte sedimentation rate (ESR) (74 +/- 19 vs 56 +/- 24 mm/h; p< 0.05, Student's t test).

CONCLUSION

Childhood pelvic AHO is relatively uncommon and produces variable signs and symptoms that are often attributed to another process. The results of our study show the ability of MRI to provide additional information that affected patient management in cases of pelvic abscess. We therefore advocate the use of MRI as the imaging technique of choice for any child suspected of having pelvic AHO.

Pyomyositis associated with hematological malignancy: case report and review of the literature

Pyomyositis occurs most commonly in patients with various immunosuppressive diseases. However, the association of pyomyositis with an underlying hematological malignancy has not been reviewed. We present herein a relevant case and also review the available literature regarding the association of non-tropical pyomyositis and hematological malignancies. The case patient, a 46-year old female, had non-tropical pyomyositis of the iliopsoas and obturator muscles due to Staphylococcus aureus and underlying Hodgkin's disease. Forty-four patients with pyomyositis and an associated hematological malignant disease have been reported in the literature. The most common types of hematological oncology diseases found were acute lymphocytic leukemia (present in 11/44 patients (25%)) and multiple myeloma (7/44 patients (15.9%)). Staphylococcus aureus was the most common cause of pyomyositis (26 out of 44 patients (59.1%)). The muscles of the thigh were most commonly affected (18/44 patients (40.9%)). Medical therapy with antibiotics and surgical drainage were employed in 25/44 (56.8%) of the patients. Thirty out of 44 (68.2%) of the patients had a successful outcome. Death occurred in 5/44 (11.4%) patients. In cases of pyomyositis, the physician should consider an underlying hematological malignancy.

Internal obturator muscle abscess caused by Klebsiella pneumoniae

Obturator internus muscle abscess is an infrequent form of pyomyositis. To date, this disease has been described almost exclusively in children and young adults, and in most cases the causative agents are Gram-positive bacteria. We present the first report of obturator internus muscle abscess caused by a highly antibiotic resistant Klebsiella pneumoniae, in an elderly diabetic patient. Once considered very rare, Gram-negative pyomyositis is increasingly reported, and is an important concern in diabetic patients. Since pyomyositis can easily be missed if not considered, physicians should become familiar with this condition, and consider it in the differential diagnosis of septic diabetic patients.