Two Roads to Diagnose Primary Esophageal Adenoid Cystic Carcinoma in the Mediastinum

During early embryonic development, the respiratory diverticulum originates from the primitive foregut where branching occurs, forming the trachea anteriorly and the esophagus posteriorly. As such, malignant processes occurring within the esophagus or trachea may have important diagnostic and clinical implications for one another. We report a rare esophageal malignant neoplasm located in the posterior mediastinum presenting with airway obstruction most likely related to the anatomic origin of these structures. Adenoid cystic carcinoma (ACC) is a malignant epithelial tumor that usually originates in the salivary glands of the head and neck.^, Primary esophageal ACC (EACC) is extremely rare, accounting for <0.1% of primary tumors in the esophagus.^, EACC usually has submucosal involvement on presentation; thus, it is believed to originate from the submucosal esophageal glands. Approximately 60 cases have been reported in the literature. The most common clinical presentation includes progressive dysphagia and food regurgitation. Initial diagnostic modalities for EACC include gastrointestinal endoscopic ultrasound fine-needle aspiration (EUS-FNA), but low diagnostic yields have been reported in the literature. Moreover, many cases of EACC are diagnosed after surgical resection. Herein, we present a case of EACC diagnosed through endobronchial ultrasound-guided fine-needle aspiration (EBUS-FNA).

An 81-year-old man with a 17-pack-year smoking history presented with a 6-month history of nonproductive cough and progressive dyspnea. In addition, he had chronic, mild, nonprogressive dysphagia. Pulmonary function tests revealed a severe obstructive ventilatory impairment. Chest computed tomography showed a 2.7 × 2.1-cm lesion in the subcarinal compartment of the mediastinum (Figure 1). In view of his predominant respiratory symptoms and the lesion’s proximity to the airway, bronchoscopy was performed, which showed a left main obstruction due to apparent external mass effect with left lung collapse in all its segments (Figure 2A ). Endobronchial ultrasound showed a lesion with mixed echogenicity (Figure 2B). EBUS-FNA revealed aggregates of atypical epithelial cells arranged in a tubular and cribriform pattern, microcystic spaces (Figure 3A ), and globules of extracellular matrix surrounded by basaloid cells (Figure 3B). The immunostaining had strong positivity for CK7 (Figure 3C) in the ductal component and P63 in the myoepithelial component (Figure 3D); nonetheless, it was positive for CD117 (c-kit), S100, and smooth muscle actin, consistent with ACC. Subsequent upper endoscopy with EUS-FNA showed a 2.8 × 2.7-cm hypoechoic lesion in the posterior mediastinum arising from the submucosal layer of the esophageal wall (Figures 2C, 2D). Therefore, it confirmed the esophageal origin of the ACC. No lymphadenopathy or metastasis was evidenced by bronchoscopic ultrasound, endoscopic ultrasound, or fusion positron emission tomography. The patient preferred nonsurgical management and thus is undergoing radiotherapy.