Using Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration for the Diagnosis and Treatment of a Mediastinal Mass With Eccentric Calcifications: A Case Report

Abstract

Mediastinal masses present a diagnostic challenge due to their similar imaging characteristics, making distinguishing between noninfectious and infectious processes or malignancies difficult. A mediastinal abscess can result in severe life-threatening infections if left untreated. Traditional treatment approaches involve surgical debridement and drainage; however, emerging endobronchial techniques, such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), offer a less-invasive means of diagnosing and managing abscesses. Herein, we describe a case of a young male patient who exhibited nonspecific symptoms, including pleuritic chest pain, shortness of breath, and fever. Imaging revealed a mediastinal mass with granuloma formation. EBUS-TBNA successfully drained the abscess, and microbiology analysis confirmed the growth of Streptococcus intermedius. Subsequently, his symptoms resolved, and follow-up imaging demonstrated the resolution of the mass and associated calcifications. Further research is warranted to assess the role of EBUS-TBNA in benign mediastinal masses with granuloma formation.

Introduction

A granulomatous mediastinal mass is associated with infections (e.g., fungus and tuberculosis) or noninfectious causes such as sarcoidosis, occasionally mimicking malignancy.^1,2 A mediastinal abscess can lead to serious infections with high mortality if left untreated. ³ Antibiotic therapy alone is often insufficient due to poor circulation, which hinders drug delivery. ⁴ Debridement and drainage via surgical intervention have traditionally been the main methods of treating such infections.^5,6 Nevertheless, evolving endoscopic techniques, such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), are being used, which provides a less-invasive modality and an option for nonsurgical candidates.^5,6 This approach is now the standard of care in sampling lymph nodes if malignancy or sarcoidosis is suspected. However, its role in diagnosing and treating bacterial abscesses in a granulomatous mediastinal mass is less evaluated. ⁶

Case Report

A 28-year-old male patient with no significant medical history was referred to the pulmonology clinic due to a mediastinal mass seen on chest imaging.

One week prior, the patient presented to our hospital’s emergency department complaining of pleuritic chest pain, cough, low-grade fever, and shortness of breath for the past week, with flu-like symptoms that improved after taking cough medicine. He denied hemoptysis or weight loss but reported difficulty swallowing solid food. On physical examination, his vitals were stable, blood pressure was 111/80, heart rate was 105, and sat 96% on room air with normal respiratory rate. Physical examination was unremarkable, with good air entry heard bilaterally on lung auscultation. An electrocardiogram showed sinus tachycardia. Laboratory results were significant for white blood cell (WBC) count of 15.6, neutrophils of 78.8%, lymphocytes of 10%, potassium 3.4 mmol/L, and D-Dimer 470 ng/mL.

A computerized tomography angiogram (CTA) of the chest was done due to elevated D-dimer. It ruled out pulmonary embolism but showed a 7 × 4.5 × 3.5 cm subcarinal mass or lymphadenopathy with small punctate calcification, resulting in a mild mass effect on the adjacent right main pulmonary artery (Figure 1). The mass had a mean Hounsfield unit scale of 40, while the calcifications had a scale of 140 HU. Multiple mediastinal and right hilar calcified lymph nodes were also seen, with a splenic calcified granuloma. The patient is a nonsmoker and has never traveled outside the United States; he has lived in Illinois most of his life. He takes no medications, works as an Amazon delivery driver, and has no pets.

Figure 1.

Mediastinal mass (7.4 cm) with eccentric calcifications resulting in a mass effect on the right pulmonary artery.

Soon after the clinic visit, he underwent bronchoscopy with EBUS-TBNA; the procedure demonstrated copious purulence with erosion of the subcarinal mass (Station 7 lymph node) through the right and left sides of the main carina (Figure 2), which was all drained and aspirated several times using a dedicated 21-gauge FNA needle, around 10 mL of pink purulent fluid was aspirated. Samples were sent for cytopathology and microbiology. Tissue was sent to rule out malignancy. The patient was empirically prescribed amoxicillin/clavulanic acid (Amox-Clav) to continue medical treatment of the abscess. Bronchoalveolar lavage acid-fast bacilli, fungal studies, and respiratory panel were negative. Cultures from the left mainstem bronchus and lymph node aspiration were positive for Streptococcus intermedius and light growth of methicillin-susceptible Staphylococcus aureus. Lymph node aspirate cytology showed marked acute inflammation with focal necrosis. No granulomas or malignant cells were identified. Left mainstem bronchus tissue also ruled out malignancy. The patient was referred to the infectious disease clinic and was prescribed Amox-Clav and Linazolid, which, upon susceptibility results, was changed to Amox-Clav only to complete for 4 weeks.

Figure 2.

Subcarinal lymphadenopathy with purulence as seen on bronchoscopy.

An echocardiogram ruled out S intermedius endocarditis. A positron emission tomography (PET)-CT scan showed localized fluorodeoxyglucose (FDG) avid uptake in the subcarinal lymph node, indicating an infection (Figure 3). Upon 1-month follow-up, the patient reported that his symptoms resolved. A 3-month follow-up CT chest showed complete resolution of subcarinal adenopathy and calcifications but persistent calcified lymph nodes in the right hilum (Figure 4).

Figure 3.

Avid FDG uptake in subcarinal lymph node indicating infection.

Figure 4.

Almost complete resolution of the mediastinal mass and associated calcifications.

Discussion

Mediastinal abscesses are rare and difficult to diagnose due to various underlying causes and overlapping clinical and radiological presentations with other mediastinal masses. ⁷ In this case, the patient presented with nonspecific symptoms that were less suspicious of a mediastinal abscess, but imaging showed a sizeable subcarinal mass with partial calcifications, which was thought to be a granulomatous disease, possibly old histoplasmosis, given additional calcified hilum and granuloma within the spleen, with a superimposed secondary infection. Endobronchial ultrasound-guided transbronchial needle aspiration aided in diagnosing the mediastinal abscess and identifying the causative organism, in addition to successfully draining the abscess with almost complete resolution, as seen on follow-up imaging.

While there is not a defined threshold for abscess size or extent of mediastinal involvement guiding the choice between EBUS-TBNA and surgical intervention, our decision in this young patient favored attempting aspiration over immediate surgery. Opting for surgery at this stage seemed more invasive and carried an elevated risk of perforation and mediastinitis.

It is important to consider mediastinal abscesses in the differential diagnosis of enlarged mediastinal lymphadenopathy with granuloma formation. EBUS-TBNA can be used as a less-invasive modality than video-assisted thoracoscopy surgery for safe therapeutic and diagnostic drainage with fewer surgical complications. ⁸ However, in some cases, repetitive drainage may be needed.^7,8

Conclusion

This case highlights the challenges in diagnosing mediastinal masses with calcifications and recognizing and treating mediastinal abscesses. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) emerges as a safe and less-invasive approach for diagnosing such masses, while it also allows for successful drainage and identification of the responsible organism causing abscesses. In some cases, recurrent drainage may be required. Complications like mediastinitis are very rare but can happen.

EBUS-TBNA may be considered when a mediastinal abscess is accessible through bronchoscopy, and the procedure is deemed safe and feasible by the treating physician. We underscore the emerging role of EBUS-TBNA as a therapeutic option not only for sampling lymph nodes for malignancy staging but also for diagnosing and treating mediastinal infections. EBUS-TBNA is superior to blind transbronchial needle aspiration and is the recommended approach for this indication.

Prior Presentation of Abstract Statement: No previous presentation of Abstract.