Locally advanced thymic carcinoma with direct pericardial extension and atrial clot diagnosed with endoscopic ultrasound: A case report

A 31-years-old white male presented with progressive right-sided chest pain and hemoptysis for 2 weeks. Physical exam revealed reduced breath sounds in the right lower lobe. Computed tomography (CT) scan of the chest demonstrated a 5.8 3 4.9 3 4.5 cm bulky right subcarinal paraesophageal posterior mediastinal mass engulfing the bronchus intermedius and extending through the pulmonary vein into the body of the left atrium. Positron emission tomography scan demonstrated intense fluorodeoxyglucose activity in the mass suggesting malignancy. Abdominal and pelvic CT showed no metastasis or lymph nodes. A CT-guided biopsy was suggestive of basaloid lung carcinoma though thymic carcinoma could not be ruled out. EUS revealed a 4.0 3 4.8 cm mass abutting the left atrium along with a 1.8 3 2.5 cm intra-atrial thrombus (Fig. 1). A subcarinal lymph node measuring 3.0 3 1.8 cm was also seen. EUS-FNA cytology of the subcarinal lymph node revealed lymphocytes and CAM5.2, CD5-positive neoplastic cells. The patient underwent induction chemotherapy followed by right thoracotomy with resection of paraesophageal mass, complete thoracic lymphadenectomy, right lower lobectomy, and partial left atriaectomy with subsequent reconstruction of left atrium with myocardial patch. Biopsy from resected tissue showed a lobulated epithelial tumor involving the lung and myocardium (Figs. 2a and b). Most of the tumor exhibited a basaloid histology with foci and small nests of keratinization reminiscent of Hassal’s corpuscles and had lymphocytic infiltration. Immunoperoxidase stains were positive for cytokeratin (Fig. 2c) and p63 but negative for CD5, CD57, CD117, CD20, CD45, TTF-1, CAE, CEA, S-100, chromogranin, NSE, and CAM5.2. Pathologic examination was consistent with thymic carcinoma. He subsequently underwent concurrent chemoradiotherapy though chemotherapy had to be discontinued halfway through the treatment course due to increased toxicity. He had complete relief of symptoms and was leading an active life at the time of last follow-up 2 years after treatment. Follow-up CT scans were negative for metastatic disease.