A gastric dilatation

I'm carrying out a dilatation (20mm) of a distal gastric stricture. 
WHAT IS THE LIKELY AETIOLOGY OF THE STRICTURE?

■ Benign pyloric stricture

But the stricture is pre-pyloric!

■ Anastomotic stricture

Doesn't look like an anastomosis!

■ Radiotherapy stricture

But why giving radiotherapy to the stomach?

explanation

The mucosa in the 4 o'clock position looks pale and atrophic.  This is a 'scar' left after treatment of a gastric lymphoma.  Of course, the scar would look the same following Hp eradication of a MALT lymphoma.  However, this was after following chemoradiotherapy  (CRT)  for a 'Diffuse large B-cell lymphoma. Which is a far more nasty lymphoma and patients present with more advanced stage at diagnosis, and have a worse prognosis (about 75% of patients are alive at 5 yrs) than with a MALT lymphoma. 

This patient was treated with 6 cycles of R-CHOP chemotherapy and radiotherapy 30 Gy in 15 fractions.  The risk of stricturing after gastric CRT is around 5%.  My dilatations to 20mm didn't do much and the patient had to come back for a dilatation to 25mm before symptoms improved.