A Collision Tumor of the Esophagus: Mixed Squamous Cell Carcinoma and Neuroendocrine Carcinoma.

Collision tumors are extremely rare, and currently, no therapeutic protocols are established. A 64-year-old man presented to his physician with complaints of right chest and abdominal pain. The contrast-enhanced CT scan showed a mass measuring 3.6 cm around the gastric fundus. Esophagogastroduodenoscopy was performed and a semicircular longitudinal ulcerative mass was found at the distal esophagus. A mass measuring about 4 cm with central ulceration was noted at the cardia. The esophageal biopsy revealed positivity for a component of neuroendocrine carcinoma adjacent to a squamous cell carcinoma. PET-CT revealed a mass in the esophagus and cardia and several tumors in the whole liver, pancreas, and bone. The patient was finally diagnosed with a collision tumor of the esophagus with multiple metastases. In conclusion, patients with collision tumors must undergo active multidisciplinary management that will include pathologists and oncologists, who will decide on proper treatment strategies.