Case Presentation: A 44-year-old male with a past medical history of sleep apnea on CPAP, alcohol abuse, tonsillectomy, and deviated nasal septum (DNS) repair presented with generalized weakness, body aches, and headache. He denied nausea, vomiting, diarrhea, dysuria, hematuria, chest pain, and shortness of breath. There was no history of neck stiffness or photophobia. On presentation, the patient was afebrile and hemodynamically stable. An EKG showed sinus rhythm, and a chest X-ray was unremarkable. A CT angiogram ruled out pulmonary embolism but revealed multiple pulmonary nodules, with the differential including inflammatory or neoplastic processes. A CT abdomen showed mild diffuse fatty liver infiltration and a 1.9 cm midline anterior abdominal wall paramedian hernia containing fat only.Lab Findings – Figure 1Empiric antibiotics, including Zosyn and vancomycin, were initiated in the emergency department, and IV Zosyn was continued. However, the patient developed a fever, and blood cultures were positive for methicillin-sensitive Staphylococcus aureus (MSSA). A 2D echocardiogram showed normal ejection fraction of 60%, and no vegetations were seen. A transesophageal echocardiogram also showed no evidence of abscess or vegetations.Upon further evaluation, the patient mentioned occasional discomfort in the lateral aspect of his right thigh, which he had not reported initially. Physical examination revealed no visible swelling, erythema, warmth, or significant tenderness, although there was questionable crepitus. A non-contrast CT of the femur showed edema in and around the quadriceps muscle group, particularly the vastus lateralis, with fluid in the subcutaneous tissue anterior to the knee, but no discrete drainable abscess or subcutaneous emphysema was noted. MRI with and without contrast revealed a multiloculated intramuscular abscess within the right quadriceps group, with the largest fluid collection measuring 6.3 x 2.6 x 2.2 cm. Infectious disease and orthopedic consultations were obtained, and the patient underwent incision and drainage of the right thigh abscess. Culture of the abscess confirmed MSSA, and antibiotic therapy was switched to cefazolin based on infectious disease recommendations. Follow-up blood cultures were negative, and the patient completed a four-week course of antibiotic therapy.
Discussion: Septic pulmonary nodules are commonly associated with risk factors such as congenital heart disease, intravenous drug use, the presence of central lines, or prosthetic valves. Pyomyositis, although rare, can be a source of septic emboli to the lungs. While septic pulmonary emboli from deep infections are more frequently reported in pediatric populations, they can occur in adults as well, as demonstrated in this case. Interestingly, the patient did not present with a history of immunocompromise, which is often seen in such infections. As in this case, Staphylococcus aureus is the most common pathogen responsible for pyomyositis. Clinicians should recognize pyomyositis as a potential cause of septic pulmonary nodules, particularly in patients without classic signs of infection.
Conclusions: Pyomyositis should be considered in patients with pulmonary nodules and bacteremia, especially in the absence of intravenous drug use and a clear source of infection.
