Imaging Features of Soft-Tissue Infections and Other Complications in Drug Users After Direct Subcutaneous Injection (“Skin Popping”)

Ultrasound and CT findings of subcutaneous metastases in trunk and pelvis: a comprehensive analysis

OBJECTIVE

This study aimed to describe the ultrasound, CT findings, and clinical manifestations of pathologically confirmed metastases involving the subcutaneous fat layer of the trunk and pelvis.

MATERIALS AND METHODS

We included 30 patients with subcutaneous metastases in the trunk and pelvis, verified by ultrasound-guided biopsy. We comprehensively reviewed ultrasound findings of all 30 patients and contrast-enhanced CT findings of 25 patients obtained before biopsy. Medical records were reviewed, including primary malignancy type, presence of coexisting distant metastasis, and detection method leading to biopsy referral.

RESULTS

Most subcutaneous metastases were heterogeneously hypoechoic (86.7%) with well-defined margins (80.0%), lobulated (46.7%) or round-to-oval (40.0%) shape, and vascularity (96.7%). Metastases frequently exhibited no contact (53.3%) or focal contact with deep peripheral fascia, resulting in acute contact angle formation (30.0%). Common CT manifestations included central low attenuation with peripheral rim-like enhancement (60.0%) or well-circumscribed lesion with heterogeneous enhancement (32.0%). Lung cancer (46.7%) was the prevalent primary malignancy. CT was the predominant detection method (56.7%). Coexisting subcutaneous metastases were present in 50.0% of cases, and distant metastases (less subcutaneous metastases) were observed in 90.0% of patients.

CONCLUSION

This study describes typical imaging findings of subcutaneous metastases involving the trunk and pelvis. CT may play a crucial role in their early detection, and our results may assist radiologists in their diagnosis.

Abdominal Imaging Manifestations of Recreational Drug Use

Recreational drug use is a burgeoning health issue worldwide, with a variety of presenting symptoms and complications. These complications can be secondary to the toxic effects of the drug itself, drug impurities, and nonsterile injection. The abdominal radiologist is likely to encounter patients who use drugs recreationally and may be responsible for recognizing and reporting these acute conditions, which in some cases can be life threatening. Because these patients often present with an altered mental state and may deny or withhold information on drug use, the underlying cause may be difficult to determine. The most commonly used drugs worldwide include cocaine, cannabinoids, opioids, and amphetamines and their derivatives. Complications of use of these drugs that can be seen at abdominopelvic CT can involve multiple organ systems, including the soft tissue and gastrointestinal, genitourinary, vascular, and musculoskeletal systems. A diverse range of abdominal complications associated with these drugs can be seen at imaging, including disseminated infections, gastrointestinal ischemia, and visceral infarction. Radiologists should be familiar with the imaging findings of these complications to accurately diagnose these entities and help guide workup and patient treatment. ^©RSNA, 2020.

Radiographic Musculoskeletal Findings Indicating Opioid Misuse: An Overview for Orthopedic Surgeons

BACKGROUND

Given the high prevalence of musculoskeletal conditions in the USA, it is important for orthopedic surgeons to promptly identify patients who may be at risk for opioid misuse.

QUESTIONS/PURPOSES

The aim of this literature review was to elucidate various musculoskeletal pathologies and complications, as seen on imaging, that may indicate opioid misuse or opioid use disorder.

METHODS

A literature search was conducted using the PubMed, Scopus, and Cochrane Library databases for articles related to imaging findings associated with chronic opioid use or misuse in orthopedic patients. Two independent reviewers conducted the search utilizing pertinent Boolean operations.

RESULTS

We reviewed 36 full-text articles and categorized the radiographic evidence of opioid misuse as follows: soft-tissue radiologic findings, cellulitis, necrotizing fasciitis, abscess formation, retained needles, discitis, myopathy and rhabdomyolysis, osteomyelitis, septic arthritis, and septic thrombophlebitis.

CONCLUSION

Knowledge of the radiologic findings of opioid misuse will assist orthopedic surgeons in making timely diagnoses that may alter therapeutic regimens for their patients.

Nosocomial rapidly growing mycobacterial infections following laparoscopic surgery: CT imaging findings

OBJECTIVE

To identify the distribution and frequency of computed tomography (CT) findings in patients with nosocomial rapidly growing mycobacterial (RGM) infection after laparoscopic surgery.

METHOD

A descriptive retrospective study in patients with RGM infection after laparoscopic surgery who underwent CT imaging prior to initiation of therapy. The images were analyzed by two radiologists in consensus, who evaluated the skin/subcutaneous tissues, the abdominal wall, and intraperitoneal region separately. The patterns of involvement were tabulated as: densification, collections, nodules (≥1.0 cm), small nodules (<1.0 cm), pseudocavitated nodules, and small pseudocavitated nodules.

RESULTS

Twenty-six patients met the established criteria. The subcutaneous findings were: densification (88.5%), small nodules (61.5%), small pseudocavitated nodules (23.1 %), nodules (38.5%), pseudocavitated nodules (15.4%), and collections (26.9%). The findings in the abdominal wall were: densification (61.5%), pseudocavitated nodules (3.8%), and collections (15.4%). The intraperitoneal findings were: densification (46.1%), small nodules (42.3%), nodules (15.4%), and collections (11.5%).

CONCLUSION

Subcutaneous CT findings in descending order of frequency were: densification, small nodules, nodules, small pseudocavitated nodules, pseudocavitated nodules, and collections. The musculo-fascial plane CT findings were: densification, collections, and pseudocavitated nodules. The intraperitoneal CT findings were: densification, small nodules, nodules, and collections.

KEY POINTS

• Rapidly growing mycobacterial infection may occur following laparoscopy. • Post-laparoscopy mycobacterial infection CT findings are densification, collection, and nodules. • Rapidly growing mycobacterial infection following laparoscopy may involve the peritoneal cavity. • Post-laparoscopy rapidly growing mycobacterial intraperitoneal infection is not associated with ascites or lymphadenopathy.

View from the front lines: an emergency medicine perspective on clostridial infections in injection drug users

Injection drug use (IDU), specifically non-intravenous "skin-popping" of heroin, seems to provide optimal conditions for Clostridial infection and toxin production. IDU is therefore a major risk factor for wound botulism and Clostridial necrotizing soft tissue infections (NSTI) and continues to be linked to cases of tetanus. Case clusters of all 3 diseases have occurred among IDUs in Western U.S. and Europe. Medical personnel who care for the IDU population must be thoroughly familiar with the clinical presentation and management of these diseases. Wound botulism presents with bulbar symptoms and signs that are easily overlooked; rapid acquisition and administration of antitoxin can prevent neuromuscular respiratory failure. In addition to Clostridium perfringens, IDU-related NSTIs can be caused by Clostridium sordellii and Clostridium novyi, which may share a distinct clinical presentation. Early definitive NSTI management, which decreases mortality, requires a low index of suspicion on the part of emergency physicians and low threshold for surgical exploration and debridement on the part of the surgeon. Tetanus should be preventable in the IDU population through careful attention to vaccination status.

Demographic description of the presentation and treatment of lower extremity skin and soft tissue infections secondary to skin popping in intravenous drug abusers

Skin popping refers to the act of subcutaneous injection of intravenous drugs, a practice that often results in the development of cellulitis and the formation of soft tissue abscesses. Although the foot and ankle represent common injection sites, few data have described the presentation and natural history of this pathologic entity. The objective of the present study was to retrospectively assess the descriptive demographic data of a patient cohort admitted for lower extremity skin and soft tissue infection caused by intravenous drug abuse. Fifty skin popping lesions in 49 patients were identified during a 733-day data collection period (August 1, 2010 to August 31, 2012) that had been treated by the in-patient podiatric surgical service for lower extremity infection caused by intravenous drug abuse at an urban, level-one trauma center. With respect to patient race, our hospital has a typical in-patient census of 55% black patients and 25% white patients. The present patient cohort consisted of 12% black patients and 65% white patients. The mean length of stay was 5.71 ± 3.56 days, and 42 patients (85.71%) underwent some form of surgical debridement, with 31 (63.27%) having undergone a formal procedure in the operating room. Six patients (12.24%) left the hospital against medical advice or refused intervention at some definitive point of care, and 36 (73.47%) did not return for scheduled outpatient follow-up visits. Three cases (6%) resulted in minor amputation. The microbiologic culture data and common antibiotic prescriptions used in the diagnosis and treatment, respectively, of these patients have been summarized. We hope these original descriptive data can be used by other physicians treating patients at similar urban practices to improve the care of these sometimes difficult-to-treat patients and better serve this population as a whole.

Sensitivity of Computed Tomography in Detection of Perirectal Abscess

Most patients with anorectal abscess are diagnosed clinically based on pain, erythema, warmth, and fluctuance. Some patients, however, present with subtle or atypical signs. CT is easily accessible and is commonly used for diagnosis and delineation of anorectal abscess. The purpose of this study is to determine the sensitivity of CT scan in detecting perirectal abscesses and to see if immune status impacts the accuracy of CT. A retrospective study was conducted to identify patients from 2000 to 2009 with International Classification of Diseases, 9th Revision code 566 (anal or rectal abscess). Patients included had a CT scan less than 48 hours before drainage. Patients with CT-positive abscess were compared with patients with CT-negative abscess. Patients were categorized as either immunocompetent or immunosuppressed based on documentation of diabetes mellitus, cancer, human immunodeficiency virus, or end-stage renal disease. One hundred thirteen patients were included in this study. Seventy-four (65.5%) were male and the average age was 47 years. Eighty-seven of 113 (77%) patients were positive on CT for anorectal abscess. Sixty of 113 (53%) patients included in this study were immunocompromised. CT missed 26 of 113 (23%) patients with confirmed perirectal abscess. Eighteen (69%) of these patients were immunocompromised compared with CT-positive patients (42 [48%], P = 0.05). The overall sensitivity of CT in identifying abscess was 77 per cent. CT lacks sensitivity in detecting perirectal abscess, particularly in the immunocompromised patient.