Rationale: Retroperitoneal colonic perforation is a rare cause of retroperitoneal abscess. It presents, more frequently in frail elderly patients, with heterogeneous signs and symptoms which hamper the clinical diagnosis. Subcutaneous emphysema with pneumomediastinum and iliopsoas muscle abscess are unusual signs. Colonic retroperitoneal perforation may be consequent to diverticulitis or locally advanced colon cancer. Due to the anatomy of the retroperitoneal space and different physiopathology, diverticular perforation may present with air and pus collection; on the other hand perforated colon cancer may cause groin mass and psoas abscess. We reported 2 cases of colonic retroperitoneal perforation from diverticulitis and locally advanced colon cancer, respectively. Aim of this report is to improve differential diagnosis based on clinical signs. Patients’ concerns: A 71-year-old man presented with pain in his left side, fatigue, fever, nausea, massive subcutaneous emphysema of the neck, and Blumberg sign in the left iliac fossa. A 67-year-old man presented with abdominal pain, sub-occlusion, left groin mass, left groin, and lower limb pain during walking, negative Blumberg sign. Diagnosis: In the first patient the computerized tomography revealed pneumoperitoneum, gas in the mesosigma, pneumomediastinum, wall thickening of the descending colon, and retroperitoneal collection from diverticular perforation. In the second patient abdominal CT scan found thickening of the sigmoid colon adherent to the iliopsoas and fluid collection. Interventions: In the first patient, a left hemicolectomy extending to the transverse colon, followed by a toilette and debridement of the retroperitoneum were performed. In the second patient, tumor of descending colon perforated in the retroperitoneum with iliopsoas abscess was treated with left hemicolectomy and a drainage of the abscess. Outcomes: The first patient underwent right colectomy with ileostomy in the 7^th postoperative day for large bowel necrosis. He died of sepsis 2 days after. The second patient had regular postoperative and he is still alive. Lessons: The spread of retroperitoneal abscess in complicated colonic diverticulitis is different from that in advanced colonic cancer. The former can present with a subcutaneous emphysema, the latter with a groin mass. Hence a thorough clinical examination and radiological studies are needed to diagnose these conditions.

Introduction: In recent years, there has been an increase in the non-medical use of psychoactive prescription drugs including pregabalin (PGB). Studies have shown that multiple drug users and patients in methadone treatment programs administered PGB at high dosages in order to achieve euphoria, reduce withdrawal symptoms, or potentiate the effects of methadone. For these reasons, accurate toxicological monitoring is required for these high-risk individuals. Materials and Methods: The present study investigated whether PGB could be detected in the hair samples of 250 patients with a history of opiate dependency, and under toxicological surveillance assess their compliance with methadone maintenance therapy. Results: Opiates were found in 54/250 of all hair samples, while cannabis was present in 74/250 patients, cocaine was detected in 21/250 patients, and benzodiazepines without prescription were identified in 49/250 patients. As expected, methadone was present in all 250 patients (100%). PGB without prescription was found in the hair samples of 35/250 patients (14%). Of these, 91.43% were male, 48.57% were <30 y old, and 45.71% were between ages 30 and 50 y. There were no apparent associations among PGB use, daily methadone dosage, and duration of methadone maintenance therapy. Psychiatric comorbidities were present in 25.71% of the patients abusing PGB. Anxiety (55.56%) and depression (33.33%) were the most prevalent psychiatric disorders. Discussion: Most of the patients taking PGB (57.14%) used other drugs (especially opiates) concurrently. The utility of hair analysis is explained by easy and rapid sample collection and the ability of the hair to reflect long-term drug use and incorporate drug metabolites. The findings of this study suggested that PGB has significant potential for abuse by high-risk populations such as opioid users and patients with dual diagnosis. These risks are particularly high in cases of poly-drug use and drug intake that are not in compliance with prescription guidelines.