We present a case of a 14-year-old girl with gastric large cell lympho
ma. The girl's lymphoma was characterized by the presence of mucosa-as
sociated lymphoid tissue. Infection with Helicobacter pylori (HP) was
ascertained at the time of diagnosis. The girl was successfully treate
d by a combination of chemotherapy (MACOP-B) and anti-HP drugs (omepra
zole plus amoxicillin). Thrombus of the inferior vena cava, a rare com
plication, evolved during treatment.