Real-time identification of life-threatening necrotizing soft-tissue infections using indocyanine green fluorescence imaging.

Significance: Necrotizing soft-tissue infections (NSTIs) are life-threatening infections with a cumulative case fatality rate of 21%. The initial presentation of an NSTI is non-specific, frequently leading to misdiagnosis and delays in care. No current strategies yield an accurate, real-time diagnosis of an NSTI. Aim: A first-in-kind, observational, clinical pilot study tested the hypothesis that measurable fluorescence signal voids occur in NSTI-affected tissues following intravenous administration and imaging of perfusion-based indocyanine green (ICG) fluorescence. This hypothesis is based on the established knowledge that NSTI is associated with local microvascular thrombosis. Approach: Adult patients presenting to the Emergency Department of a tertiary care medical center at high risk for NSTI were prospectively enrolled and imaged with a commercial fluorescence imager. Single-frame fluorescence snapshot and first-pass perfusion kinetic parameters-ingress slope (IS), time-to-peak (TTP) intensity, and maximum fluorescence intensity (IMAX)-were quantified using a dynamic contrast-enhanced fluorescence imaging technique. Clinical variables (comorbidities, blood laboratory values), fluorescence parameters, and fluorescence signal-to-background ratios (SBRs) were compared to final infection diagnosis. Results: Fourteen patients were enrolled and imaged (six NSTI, six cellulitis, one diabetes mellitus-associated gangrene, and one osteomyelitis). Clinical variables demonstrated no statistically significant differences between NSTI and non-NSTI patient groups (p-value≥0.22). All NSTI cases exhibited prominent fluorescence signal voids in affected tissues, including tissue features not visible to the naked eye. All cellulitis cases exhibited a hyperemic response with increased fluorescence and no distinct signal voids. Median lesion-to-background tissue SBRs based on snapshot, IS, TTP, and IMAX parameter maps ranged from 3.2 to 9.1, 2.2 to 33.8, 1.0 to 7.5, and 1.5 to 12.7, respectively, for the NSTI patient group. All fluorescence parameters except TTP demonstrated statistically significant differences between NSTI and cellulitis patient groups (p-value<0.05). Conclusions: Real-time, accurate discrimination of NSTIs compared with non-necrotizing infections may be possible with perfusion-based ICG fluorescence imaging.

No role for standard imaging workup of patients with clinically evident necrotizing soft tissue infections: a national retrospective multicenter cohort study.

PURPOSE: To assess the diagnostic contribution of different imaging studies to diagnose necrotizing soft tissue infections (NSTIs) and the time to surgery in relation to imaging with the hypothesis that imaging studies may lead to significant delays without being able to sufficiently dismiss or confirm the diagnosis since a NSTI is a surgical diagnosis. METHODS: A retrospective multicenter cohort study of all NSTI patients between 2010 and 2020 was conducted. The primary outcome was the number of cases in which imaging contributed to or led to change in treatment. The secondary outcomes were time to treatment determined by the time from presentation to surgery and patient outcomes (amputation, intensive care unit (ICU) admission, length of ICU stay, hospital stay, and mortality). RESULTS: A total of 181 eligible NSTI patients were included. The overall mortality was 21% (n = 38). Ninety-eight patients (53%) received imaging in the diagnostic workup. In patients with a clinical suspicion of a NSTI, 81% (n = 85) went directly to the operating room and 19% (n = 20) underwent imaging before surgery; imaging was contributing in only 15% (n = 3) by ruling out or determining underlying causes. In patients without a clinical suspicion of a NSTI, the diagnosis of NSTI was considered in 35% and only after imaging was obtained. CONCLUSION: In patients with clinically evident NSTIs, there is no role for standard imaging workup unless it is used to examine underlying diseases (e.g., diverticulitis, pancreatitis). In atypical presenting NSTIs, CT or MRI scans provided the most useful information. To prevent unnecessary imaging and radiation and not delay treatment, the decision to perform imaging studies in patients with a clinical suspicion of a NSTI must be made extremely careful.

Musculoskeletal infections through direct inoculation.

Musculoskeletal infections consist of different clinical conditions that are commonly encountered in daily clinical settings. As clinical findings and even laboratory tests cannot always be specific, imaging plays a crucial role in the diagnosis and treatment of these cases. Musculoskeletal infections most commonly occur secondary to direct inoculation into the skin involuntarily affected by trauma, microorganism, foreign bodies, or in diabetic ulcers; direct infections can also occur from voluntary causes due to surgery, vaccinations, or other iatrogenic procedures. Hematogenous spread of infection from a remote focus can also be a cause for musculoskeletal infections. Risk factors for soft tissue and bone infections include immunosuppression, old age, corticosteroid use, systemic illnesses, malnutrition, obesity, and burns. Most literature discusses musculoskeletal infections according to the diagnostic tools or forms of infection seen in different soft tissue anatomical planes or bones. This review article aims to evaluate musculoskeletal infections that occur due to direct inoculation to the musculoskeletal tissues, by focusing on the traumatic mechanism with emphasis on the radiological findings.

Ultrasonography for Skin and Soft Tissue Infections, Noninfectious Cysts, Foreign Bodies, and Burns in the Critical Care Setting.

There are multiple opportunities for the use of ultrasonography in the diagnosis of skin and soft tissue differentials. Ultrasonography is inexpensive, easily reproducible, and able to provide real-time data in situations where condition changes and progression are common. Not only does bedside ultrasonography provide the clinician an in-depth look beyond epidermal structures into body cavities, it remains a safe, nonionizing radiating, effective, cost-efficient, reliable, and accessible tool for the emergency management of life- and limb-threatening integumentary infections. Unnecessary invasive procedures are minimized, providing improved patient outcomes. Integumentary abnormalities secondary to trauma, surgery, and hospitalization are common among critical care patients. This article provides a brief overview and evidence-based recommendations for the use of ultrasonography in the critical care setting for integumentary system conditions, including common skin and soft tissue differentials, foreign bodies, and burn depth assessment.

Anatomic and Treatment Descriptive Features of Foot Infections Presenting With Radiographic Soft Tissue Emphysema.

Foot infections associated with soft tissue emphysema, or the radiographic appearance of gas, are widely considered to necessitate urgent decompression with excisional debridement of the necrotic and infectious tissue burden. The objective of this investigation was to describe anatomic features and clinical outcomes associated with the presence of soft tissue emphysema in foot infections. A retrospective chart review was performed of 62 subjects meeting selection criteria. These were primarily male (74.2%), with a history of diabetes mellitus (85.5%), and without a history of previous lower extremity revascularization (98.4%). The primary radiographic location of the soft tissue emphysema was most frequently in the forefoot (61.3%), followed by the midfoot (21.0%), and rearfoot (16.1%). The soft tissue emphysema was most frequently observed primarily in the dorsal foot tissue (49.2%), followed by both dorsal and plantar foot tissue (27.4%), and the plantar foot tissue (24.2%). The soft tissue emphysema was confined to the primary anatomic location in 74.2% of subjects, while 25.8% of cases demonstrated extension into a more proximal anatomic area. Eighty-two percent of subjects underwent a bedside incision and drainage procedure on presentation in the emergency department, and 95.2% underwent a formal incision and drainage procedure in the operating room at 1.05 ± 0.79 (0-5) postadmission days. Twenty-seven percent of subjects had an unplanned 30-day readmission and 17.7% underwent an unplanned reoperation within 30 days following the index discharge. Fifty-two percent of subjects underwent a minor or major amputation during the index admission, while 33.9% eventually resulted in major limb amputation within 12 months. We hope that this investigation adds to the body of knowledge and provides expectations with respect to the evaluation and treatment of foot soft tissue infections complicated by the presence of radiographic soft tissue emphysema.

Soft tissue masses of the epitrochlear region.

The epitrochlear lymph nodes (ELN) are rarely examined clinically and are difficult to identify radiologically in healthy patients. They are, therefore, generally under appreciated as a source of significant pathology. Despite this, enlargement of an ELN is almost always secondary to a pathological process, the differential for which is relatively narrow. The following pictorial review illustrates the spectrum of infectious, inflammatory and malignant conditions affecting the ELN, some of which are quite specific to this location. We also emphasise the importance of distinguishing enlarged ELNs from benign and malignant non-nodal soft tissue masses, which can have very similar clinical presentation and imaging appearances.

Necrotising soft tissue infection in western Sydney: An 8-year experience.

BACKGROUND: This study aimed to assess the risk factors, management, imaging validity, Laboratory Risk Indicator for Necrotising infection (LRINEC) score and outcomes of necrotising soft tissue infection (NSTI) at a western Sydney tertiary hospital. METHODS: A retrospective study was conducted of all patients with NSTI from 2012 to 2019 at our institution. Patient characteristics, imaging, microbiology and site, LRINEC score, surgical management and outcomes/disposition were collected. RESULTS: Thirty-six patients met the inclusion criteria with mean age of 52 years and body mass index of 38.1; 55.6% were male, 48% of Polynesian descent and 55.6% were diabetic. The most frequent sites of NSTI were perineal (30.6%), lower limb (30.6%), perianal (19.3%) and trunk (11.1%). A total of 64% of patients underwent computed tomography radiological imaging with diagnostic accuracy of 50%. The mean LRINEC score was 7 (1-20). A total of 52.8% were transferred from another facility or non-surgical teams which delayed surgical review by 11.4 h (P < 0.03) and operating time by 12.4 h (P < 0.04) compared with direct emergency department referrals to the on-call surgical team. There was no statistical difference in outcomes in both groups. The overall average time to surgical debridement was 16.2 h (standard deviation 19.6, range 3.4-105.1). The mean hospital length of stay was 20.9 days; 44.4% of patients were transferred for rehabilitation or plastic reconstruction with a single mortality from multi-organ failure. CONCLUSION: The optimal management of NSTI requires a high index of suspicion and LRINEC score is a useful adjunct in aiding a clinician's decision. Early surgical debridement within 24 h of diagnosis and a multidisciplinary approach is associated with a lower mortality rate.

Iatrogenic subcutaneous emphysema in aesthetic breast augmentation Medicolegal aspects.

The aim of the present study was to investigate clinical results and medico-legal aspects related to the surgical procedure of mini breast augmentation. In the present case, a 28-year-old young woman with bilateral mammary hypoplasia underwent surgery, under local anesthesia, with the placement of 150 cc breast implants in the sub-glandular plane. We report a case of dramatic isolated subcutaneous emphysema without pneumothorax and pneumomediastinum to be related in terms of a causal link to the surgical procedure which the patient underwent. The plastic surgeon proceeded to replace a breast implant that presumably, represented the vehicle of transmission of the suspected pathogen responsible for the infection, to become a causal role for the infectious manifestation. This case report is an emblematic example of the need for a careful and correct surgical procedure, in order to avoid serious consequences as in the case in question, burdened by the occurrence of unsafe conditions for the patient. Compliance with the guidelines and the technical datasheet of breast implants is essential in order to avoid the concrete hypothesis of professional liability. KEY WORDS: Aesthetic breast augmentation, Breast implant, Iatrogenic subcutaneous emphysema.

An unexpected host in a soft-tissue lesion of thigh.

Rhinosporidiosis is an enigmatic entity and poses a major health problem in the developing countries of South-East Asia. A soft friable polypoid nasal mass is the most common presentation, while sparse literature is available on extranasal involvement. We describe the case of a 35-year-old female patient who presented with a slow-growing soft-tissue swelling with ulceration over the thigh. On clinical and radiological examination, a provisional diagnosis of soft-tissue neoplasm was made. After resection, histopathological sections showed a closely packed cyst with innumerable endospores. The present case report documents the rare occurrence of an incidentally detected cutaneous rhinosporidiosis causing diagnostic difficulty.

Sonographic assessment of musculoskeletal causes of calf pain and swelling.

Calf pain or swelling is a common presentation to the emergency department. The differential diagnoses are wide. Deep vein thrombosis (DVT) is often the first diagnosis to be excluded given its potentially fatal complications. Musculoskeletal causes of calf pain or swelling such as Baker's cyst, muscle or tendon tear, soft tissue infection, and inflammation are not uncommon and can often be confidently diagnosed with ultrasonography (US). Familiarity with these conditions and the sonographic findings would be useful in making timely and correct diagnosis.

Radiographic Soft Tissue Thickness Differentiating Pyogenic Flexor Tenosynovitis From Other Finger Infections.

PURPOSE: Characteristic swelling has been described as a differentiating sign of pyogenic flexor tenosynovitis (PFT) but has not been validated. We conducted a retrospective study of adults with finger infections to compare radiographic parameters of soft tissue dimensions. Our hypothesis was that in patients with digit infections, radiographic soft tissue thickness measurement would differ between PFT and non-PFT infected digits. METHODS: Patients with a finger infection and radiographic evaluation were identified retrospectively at a large academic medical center and divided into 2 groups: PFT (n = 31) and non-PFT infections (n = 31). We defined PFT as purulence in the tendon sheath or positive culture growth from the sheath at surgery. Non-PFT infections included all other finger infections such as abscesses and cellulitis. A total of 15 radiographic measurements were made on all included digits. Ratios and differences were calculated to characterize the pattern of swelling for each infected finger. Bivariate analysis was performed to identify potential predictor variables between the PFT and non-PFT groups. Logistic regression was performed to reduce confounding and model potential relationships. RESULTS: Neither presence of diffuse swelling nor the shape of finger swelling distinguished PFT from non-PFT infections. All finger infections resulted in diffuse swelling. Pyogenic flexor tenosynovitis was distinguished by differential volar soft tissue thickness minus dorsal soft tissue thickness on radiographs at the proximal phalanx level (9 ± 1 mm for PFT vs 5 ± 1 mm for non-PFT). This was an independent predictor of PFT. The area under the receiver operating curve was 0.83 (95% confidence interval, 0.73-0.94). A difference between volar and dorsal soft tissue swelling of 7 mm or greater had a positive predictive value of 82% with a sensitivity of 84% and specificity of 74%. A difference of 10 mm predicted PFT infection with 76% probability (95% confidence interval, 73% to 99%). CONCLUSIONS: Pyogenic flexor tenosynovitis may result in uniform finger swelling, but this does not appear to distinguish PFT from other finger infections. Acute PFT swelling is distinguished by differential volar versus dorsal radiographic soft tissue thickness at the level of the proximal phalanx. The term "fusiform swelling" is a misnomer for the appearance of acute PFT because the finger is not spindle-shaped. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic IV.

Necrotizing Myositis: A Rare Necrotizing Soft Tissue Infection Involving Muscle.

INTRODUCTION: Necrotizing myositis (NM) is an extremely rare necrotizing soft tissue infection involving muscle. Unlike similar infections (eg, necrotizing fasciitis, clostridial myonecrosis) that can be more readily diagnosed, NM can have a benign presentation then rapidly progress into a life-threatening condition with a mortality rate of 100% without surgical intervention. CASE REPORT: A 74-year-old man with a history of prostate cancer with radiation therapy, seed implants, and 2 transurethral resection procedures presented to the emergency department after a fall. He was initially diagnosed and treated for urosepsis. Sixteen hours after presentation, he complained of pain and swelling of his right groin. Computed tomography of the abdomen and pelvis showed gas findings suspicious for necrotizing infection of the bilateral thighs. Surgical exploration revealed NM. Separate cultures from the left thigh and bladder grew Streptococcus intermedius, Clostridium clostridioforme, and Peptostreptococcus, suggesting a possible common source of infection from the prostate gland or the osteomyelitic pubic symphysis, which subsequently spread to the bilateral thighs. CONCLUSIONS: To the best of the authors' knowledge, this is the first reported case of S intermedius and C clostridioforme causing NM. A high index of suspicion is required for extremely rare conditions like NM, because early diagnosis and surgical intervention significantly reduce mortality.

High diagnostic accuracy of white blood cell scintigraphy for fracture related infections: Results of a large retrospective single-center study.

INTRODUCTION: White blood cell (WBC) scintigraphy for diagnosing fracture-related infections (FRIs) has only been investigated in small patient series. Aims of this study were (1) to establish the accuracy of WBC scintigraphy for diagnosing FRIs, and (2) to investigate whether the duration of the time interval between surgery and WBC scintigraphy influences its accuracy. PATIENTS AND METHODS: 192 consecutive WBC scintigraphies with 99mTc-HMPAO-labelled autologous leucocytes performed for suspected peripheral FRI were included. The golden standard was based on the outcome of microbiological investigation in case of surgery, or - when these were not available - on clinical follow-up of at least six months. The discriminative ability of the imaging modalities was quantified by several measures of diagnostic accuracy. A multivariable logistic regression analysis was performed to identify predictive variables of a false-positive or false-negative WBC scintigraphy test result. RESULTS: WBC scintigraphy had a sensitivity of 0.79, a specificity of 0.97, a positive predicting value of 0.91, a negative predicting value of 0.93 and a diagnostic accuracy of 0.92 for detecting an FRI in the peripheral skeleton. The duration of the interval between surgery and the WBC scintigraphy did not influence its diagnostic accuracy; neither did concomitant use of antibiotics or NSAIDs. There were 11 patients with a false-negative (FN) WBC scintigraphy, the majority of these patients (n = 9, 82%) suffered from an infected nonunion. Four patients had a false-positive (FP) WBC scintigraphy. CONCLUSIONS: WBC scintigraphy showed a high diagnostic accuracy (0.92) for detecting FRIs in the peripheral skeleton. Duration of the time interval between surgery for the initial injury and the WBC did not influence the results which indicate that WBC scintigraphy is accurate shortly after surgery.

Literature review and a case report of spontaneous subscapular abscess in a child.

Subscapular space is an uncommon site for abscess formation. There are only seven reports of subscapular abscesses in the literature. Only three of these cases are reported in children. We recently treated a child with subscapular abscess. We performed the literature search using a combination of the keywords: subscapular, scapular, abscess and infection. One case was diagnosed on post-mortem autopsy, and only three of these cases are reported in children. The organism was Staphylococcus aureus in five cases (two were methicillin-resistant S. aureus), Haemophilus influenzae in one case, and no organism was grown in the last case. (Patient received a course of empirical antibiotics and samples did not grow any organism.) We describe a case of spontaneous subscapular abscess in a 7-year-old boy. The abscess was visualised on magnetic resonance imaging (MRI), and the organism was identified as S. aureus bacteria. The abscess was treated surgically with debridement and antibiotics, and the patient had full recovery with no subsequent effects. Subscapular abscess needs high index of suspicion and early imaging investigation. MRI is the modality of choice for accurate diagnosis. Early intervention leads to favourable outcome, while delays in diagnosis can be fatal.

Isolated subcutaneous nontuberculous mycobacterial infection: a rare case initially mischaracterized as a soft tissue malignancy.

The occurrence of nontuberculous mycobacterial (NTM) infection is rare, and the involvement of the musculoskeletal system is even less common. However, the incidence of soft tissue and skin NTM infection is increasing, particularly in patients who undergo injections and minor surgical procedures. Given the non-specific clinical manifestations of NTM infection, the lack of knowledge among physicians regarding this rare infection could lead to inaccurate and delayed diagnosis. Herein, we present a case of an isolated subcutaneous NTM infection caused by Mycobacterium abscessus in the upper back of an immunocompetent 68-year-old woman. The clinical presentation, magnetic resonance imaging findings (including diffusion-weighted imaging), and pathologic findings of subcutaneous NTM infection are described and compared with those of tuberculosis and tumor presentations to provide a more accurate clinical picture for a differential diagnosis.

Molecular imaging in musculoskeletal infections with 99mTc-UBI 29-41 SPECT/CT.

OBJECTIVE: To determine the added value of CT over planar and SPECT-only imaging in the diagnosis of musculoskeletal infection using 99mTc-UBI 29-4. MATERIALS AND METHODS: 184 patients with suspected musculoskeletal infection who underwent planar and SPECT/CT imaging with 99mTc-UBI 29-41 were included. Planar, SPECT-only and SPECT/CT images were reviewed by two independent analysts for presence of bone or soft tissue infection. Final diagnosis was confirmed with tissue cultures, surgery/histology or clinical follow-up. RESULTS: 99mTc-UBI 29-41 was true positive in 105/184 patients and true negative in 65/184 patients. When differentiating between soft tissue and bone infection, planar + SPECT-only imaging had a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 95.0, 74.3, 84.8, 91.3 and 86.9%, respectively, versus 99.0, 94.5, 92.5, 98.5 and 94.5% for SPECT/CT. SPECT/CT resulted in a change in reviewers' confidence in the final diagnosis in 91/184 patients. Inter-observer agreement was better with SPECT/CT compared with planar + SPECT imaging (kappa 0.87, 95% CI 0.71-0.85 versus kappa 0.81, 95% CI 0.58-0.75). CONCLUSION: Addition of CT to planar and SPECT-only imaging led to an increase in diagnostic performance and an improvement in reviewers' confidence and inter-observer agreement in differentiating bone from soft tissue infection.