Localised malignant mesothelioma presenting as an esophageal mass: An unusual manifestation

Malignant mesothelioma is an aggressive neoplasm arising from mesothelial cells, typically presenting with pleural thickening, pleural effusions, or respiratory symptoms. Dysphagia as a presenting symptom is extremely uncommon, and esophageal involvement is rare. We report a 71-year-old male with an 18-month history of progressive dysphagia and significant weight loss. Initial gastroscopy was unremarkable, but repeat endoscopy revealed a smooth lower esophageal stricture. Contrast-enhanced CT demonstrated a well-circumscribed esophageal mass with minimal pleural thickening, and PET-CT confirmed high FDG uptake in the mass and subtle anterior and posterior mediastinal pleural foci. Endoscopic ultrasound-guided fine-needle aspiration of the esophageal lesion revealed epithelioid cells positive for mesothelial markers (CK5, D2-40, WT1, Calretinin, CK7) with loss of BAP1 and MTAP, consistent with epithelioid mesothelioma. The patient was commenced on immunotherapy but lost to follow-up. This case represents an unusual manifestation of localized malignant mesothelioma presenting primarily as an esophageal mass, with minimal pleural disease. The diagnosis was established via endoscopic ultrasound-guided fine-needle aspiration, highlighting the utility of minimally invasive techniques in atypical presentations. It underscores the importance of considering mesothelioma in the differential diagnosis of unexplained esophageal or mediastinal masses, even in the absence of classic pleural findings. Mesothelioma can rarely present with dominant esophageal involvement. Awareness of this atypical presentation facilitates timely diagnosis, appropriate management, and may prevent diagnostic delays in patients presenting with dysphagia.