The patient went for gastroscopy and biopsy:

Microscopy: The specimen consists mainly of blood and fibrin, along with admixed fragments of the tumour. The tumour is composed of a haphazard arrangement of spindle cells that have fairly uniform elongated nuclei with blunt ends, and eosinophilic cytoplasm. The stroma shows myxoid alteration with focal hyalinosis. Immunoperoxidase stains have been performed and the spindle cell population shows strong positive staining for CD117 (cKit) and does not stain with desmin, SMA or S-100. Only a scant amount of tumour remains in the block. 

Although only a scant amount of the tumour is present, and this has a non-specific morphology, the immunoprofile (CD117+ / desmin-) favours a GIST.

Conclusion: Oesophageal lesion, biopsy: Spindle cell tumour, features favouring a gastrointestinal stromal tumour (GIST).