Woman with lower back pain and left thigh pain

A 42-year-old female caregiver presented with progressive lower back pain radiating to the left thigh over 3 months. She experienced difficulty extending her left leg due to nocturnal exacerbation of pain, affecting her sleep. Physical examination revealed an abdominal mass in the left lower quadrant with tenderness upon palpation. Vital signs were mostly normal, except for elevated blood pressure (159/108 mmHg). Neurological assessment demonstrated a negative straight leg raising test. Plain radiography and point-of-care ultrasound were conducted, as shown in Figures 1 and 2. The presence of the psoas line observed on abdominal radiographs is attributed to adipose tissue accumulation adjacent to the psoas muscle, thus serving as an indicator for potential retroperitoneal and paraspinal pathologies.1 In cases where retroperitoneal lesions are suspected, point-of-care ultrasound can aid emergency physicians in diagnosing tumors, hemorrhage, or abscess formation.2, 3 In this case, magnetic resonance imaging of the spine and computed tomography of the abdomen were conducted, as shown in Figures 3 and 4; thus, psoas muscle tumor was confirmed, and tumor biopsy and excision revealed a large abdominal tumor adherent to the left iliac vessels and left ureter during surgery (Figure 5). Despite a 5-day culture period, no growth was observed. Pathological analysis indicated a poorly differentiated carcinoma, potentially originating from the female genital organs or lung. Subsequently, the patient chose to undergo further treatment in her home country. This case underscores the importance of recognizing the bulging psoas line alongside symptoms such as lower abdominal/back tenderness and unilateral leg soreness and performing bedside ultrasound can aid in diagnosing a retroperitoneal lesion.