Thymic cysts are rare lesions of the anterior mediastinum or neck. Mediastinal thymic cysts account for about 1% of all mediastinal masses. The majority of thymic cysts are asymptomatic and they tend to occur in the older age group. Diagnosis is difficult before surgery and these cysts are usually detected incidentally on chest X-ray film or computed tomography scans.
48-year-old, HIV negative male, retired United States Postal Service worker, with past medical history of hypertension and dyslipidemia, that presented to ER complaining of progressive weakness, dry cough, and 3 days worsening right upper quadrant abdominal pain with right shoulder discomfort. The patient denied fever, chills, diaphoresis, shortness of breath, weight loss and hemoptysis. He also denied travel outside of Louisiana over the last 10 yrs or having pets. He has a past surgical history of right eye extraction after an accident and a right lower extremity fracture with open reduction with fixation 15 years ago. Admitted tobacco use of 1 pack per day for the last 25 yrs. He denied alcohol or illicit drug use. Vitals and physical examination were unremarkable except for right prosthetic eye and right lower extremity scar. Chest imaging disclosed a large mediastinal mass(measuring 17.3 x 11.4 cm by CT). Bronchoscopy was performed with the findings of right main stem bronchus with extrinsic compression, right middle lobe bronchus total occlusion, and right lower lobe extrinsic compression with no endobronchial lesions. Transbronchial needle aspiration at the level of the right middle lobe resulted in clear amber fluid. The patient developed hydropneumothorax that resolved with needle aspiration (WBC’s: 4,400, Seg: 48%, Lymph: 28%, Mono: 14%, RBC’s: 30,000, Protein: 6.3 mg/dL, Glucose: 86 mg/dL, LDH: 385 mg/dL, Amylase: 39 mg/dL), negative for malignant cells. The patient was referred to the thoracic surgery service. A large mass with pathologic diagnosis of benign, multiloculated thymic cyst was successfully removed without complications.
Rosai reported 18 cases that were asymptomatic and discovered incidentally. Overall, cysts of the mediastinum are uncommon, representing 12 to 30% of all mediastinal masses. Takeda reported their experience of 105 patients with cysts of the mediastinum (50 male and 55 female patients), 10 pediatric patients (< 15 years old) and 95 adult patients. Adults had a higher prevalence (14.1% vs 7.7%, p < 0.05) and there were 30 thymic cysts, 40% of which were symptomatic. The belief that all mediastinal cysts in adults should be treated surgically requires reconsideration and has been debated recently. Malignancy does not seem to be an issue. Modern imaging is highly accurate in delineating simple cysts. Resection is not without hazard. For classic simple cysts, follow-up may be appropriate. Nonetheless, any mediastinal cyst that is not classically “simple” or is one that is clearly causing symptoms warrants intervention. In many cases, percutaneous aspiration or mediastinoscopy may obviate the need for thoracotomy or VATS.
Multiloculated thymic cysts are very rare occurrences and surgical resection is the indicated management for symptomatic cases.
J.A. Urdaneta-Jaimes, None.