Abstract | November 6, 2020
Subscapular abscess extending to supraclavicular region: Surgical treatment and negative pressure wound therapy
Learning Objectives
- Identify and diagnose patients with subscapular abscesses
- Treat subscapular abscesses decrease morbidity and mortality
Introduction: Patients presenting with non-localizing symptoms of infection around the shoulder, back and chest may present as a diagnostic challenge particularly if these patients are immunosuppressed, malnourished or have a history of intravenous (IV) drug use. A subscapular abscess is part of the differential diagnosis of infection of the upper torso. MRI and CT Scans play a major role in the diagnosis of a subscapular abscess as it can be difficult to discern on physical exam alone due to the location. There are only 8 cases in literature describing subscapular abscess, therefore diagnostic and treatment plans are less well defined1. We describe a case of a diabetic patient with IV drug use history who presented with a supraclavicular abscess communicating with a larger subscapular component that grew Methicillin Resistant Staphylococcus aureus (MRSA). These abscesses underwent successful surgical treatment and the patient recovered without any residual deficits.
Case Presentation: GG is a 41 year old male with a past medical history of uncontrolled diabetes and IV drug use, who presented as a transfer from an outlying facility for shoulder pain. He complained of left shoulder and back pain that started three weeks prior to presentation followed by hallucinations requiring hospital admission. He reported IV drug injection into the forearms, but denied injection in the shoulder, neck or back. He denied any trauma or insect bites to this area. On physical exam, the patient had significant erythema of the left shoulder. No induration was noted. White blood cell count was 15,000. ESR 34 and CRP 13.60. Initial CT scan of the neck showed asymmetric subcutaneous and deep soft tissue edema in the supraclavicular region and left upper chest wall muscles with possible joint effusion. Aspiration of the left shoulder joint by orthopedic surgery team was negative on gram stain. A repeat CT Scan on Image A showed a remarkable asymmetry within the left shoulder musculature and subscapularis muscle with multiple loculated abscesses. An MRI was obtained showing a peripheral enhancing fluid collection in the left subscapularis and supraspinatus muscle measuring 6.8 cm x 2.8 cm as seen in Image B. A drain was placed into the subscapular abscess by interventional radiology (IR) team which grew MRSA. Shortly thereafter, the patient developed supraclavicular edema and erythema. Image C is a soft tissue ultrasound showing a 6.2 cm x 6 cm x 2.1 cm supraclavicular subcutaneous abscess that was incised and drained at bedside. Abscess culture once again grew MRSA. Blood cultures were negative. Pathological analysis showed acutely inflamed, partially necrotic skeletal muscle and fibroconnective tissue with no evidence of malignancy. The patient was started on intravenous Vancomycin. Follow up CT of the neck and chest showed persistent supraclavicular abscess that extended to the subscapularis abscess containing the IR drain. The patient then developed fevers with diaphoresis concerning for sepsis secondary to inadequate source control. Patient noted to have surrounding erythema tracking towards the IR drain posteriorly at the medial border of the left scapula. It was decided that the patient needed formal drainage of the subscapular and supraclavicular abscesses. He was taken to the operating room for drainage. After induction of anesthesia with a single lumen endotracheal tube, the patient was placed in the right lateral decubitus position. The left arm, shoulder, left upper back were prepped and draped in sterile fashion. An incision was made incorporating the IR drain site extending along the medial border of the left scapula.
Blunt dissection was performed in an anterior and superior direction in the subscapular space. Attention was then turned to the left supraclavicular area. This wound was explored deeply, avoiding injury to the great vessels and brachial plexus. Communication to the subscapular area was confirmed with blunt dissection. Nine liters of normal saline were used to irrigate the abscess cavities. Rongeurs were used to debride necrotic tissue from the surrounding bone. Betadine soaked kerlix was used to pack the subscapular and supraclavicular areas. After 48 hours, patient was taken back to the operating room for further irrigation and debridement. The wound bed was clean and appeared to have healthy tissue, so it was decided to place a negative pressure wound therapy device. The patient was transitioned from IV Vancomycin to oral Doxycycline based on sensitivities, and discharged home with home health. Long term follow up showed well healed wounds, with full range of motion of his left shoulder.
Discussion: Subscapular abscess is an uncommon condition making the diagnosis challenging not only because it is rare but also due to its deep location in the musculature of the back. It is associated with a higher mortality rate when diagnosis and treatment are delayed2. The few reports of subscapular abscess highlight blunt trauma and spontaneous occurrence as the primary causes1,2,3,4,5,6,7. Children and young adults are the principally affected populations, and MRI or CT scans are the mainstay of diagnostic imaging1. To date, literature describing this condition reveals deceptively non-specific signs and symptoms that often result in delay of diagnosis and treatment, which may result in fatality. Surgical drainage is the primary treatment, resulting in largely successful outcomes without chronic sequela. In this case, the patient spontaneously developed the supraclavicular and subscapular abscesses. Whether the drug use was a contributing factor or not, the patient denied injecting into his shoulder or neck. Symptoms were nonspecific and imaging showed presence of the abscesses that grew MRSA. The patients described in current literature show Staphylococcal infection as a major causative organism, though MRSA was less commonly seen than Methicillin-susceptible Staphylococcus aureus (MSSA). The feature that sets this case apart from those in current literature is the extension of the abscess from the subscapular region to the supraclavicular region. Additionally, an IR drain had been placed into the subscapular space and the supraclavicular abscess was drained at bedside. The combination of these procedures were unsuccessful in providing treatment for this problem, and ultimately required surgery.
This is confirmed in the previous cases where surgical drainage has been the mainstay of therapy. One case report describes incising the plane between the teres major and latissimus muscles with medial counter incisions to gain access to the subscapular space4. The present case makes use of incising the left trapezius and rhomboid muscles medially and connecting the subscapular space to the supraclavicular area. The most successful treatment for any abscess is surgical incision and drainage. Irrigation with copious amounts of fluid is required. It is safe to perform a second look and if the wound is healthy, negative pressure therapy is an excellent option for wound closure when compared to other closure techniques, including primary closure or healing by secondary intention with daily dressing changes. Negative pressure wound therapy is an excellent way to achieve wound closure via secondary intention. It only requires 2-3 dressing changes every week and decreases the length of time to heal. Most importantly, patients are more compliant with wound care as they are more independent and mobile with less dressing leakage than a traditional daily wet to damp dressing changes. A study by Yang C., et al regarding negative pressure wound therapy amongst the pediatric population with soft tissue abscesses requiring surgical incision and drainage shows that those treated with wound vac therapy had shorter length of stay, lower pain scores during dressing changes and had zero recurrence compared to those treated with open daily packing changes8. Whenever possible, culture specific antibiotics should be administered.
Conclusion: A high index of suspicion, accurate diagnosis and aggressive surgical therapy are required to prevent sepsis and the high mortality in patients with subscapular abscess. Negative pressure therapy could aid in expeditious wound healing.