Esophageal mixed or collision small cell-squamous cell carcinoma: Report of 6 cases and review of the literature.

BACKGROUND

Esophageal mixed neuroendocrine-nonneuroendocrine neoplasms (MiNENs) are now known as a neuroendocrine component mixed with a nonneuroendocrine component in a single neoplasm, one of which is in the form of mixed small cell-squamous cell carcinoma. Collision tumors have been excluded from the category of MiNENs, but difference between mixed and collision small cell-squamous cell carcinoma has never been reported.

METHODS

We collected six cases and reviewed 11 cases of mixed or collision small cell-squamous cell carcinoma (MCSSC); the data from 17 cases of MCSSC were analyzed to observe their clinicopathological features.

RESULTS

Most of the MCSSC patients were middle-aged and elderly, with more men than women, and most of the tumors occurred in the middle and lower esophagus. We found that in mixed cancers, the metastases were a mixture of squamous cell carcinoma and small cell carcinoma, whereas metastatic foci in collisional tumors showed simple cancer components; this phenomenon has never been reported before. Mixed cancers account for a higher proportion of small cell carcinomas, a higher pathological stage, and a worse prognosis than collisional cancers. PD-L1 (22C3) was negative in both squamous cell carcinoma and small cell carcinoma regions (<1%).

CONCLUSIONS

Mixed and collisional small cell-squamous cell carcinomas are essentially distinct tumors. In the clinical diagnostic of MCSSC, the tumor should be clearly identified as mixed or collisional carcinoma to guide the clinical treatment and prognosis more accurately.