OBJECTIVETo establish the rabbit VX2 tumor as a model for pyriform sinus carcinoma and to observe its biological features.

METHODSVX2 tumor was implanted into the pyriform sinus of 15 rabbits by direct laryngoscope. Fifteen rabbits were randomized into 3 groups (average of 5 rabbits per group). Observation of the tumor growth and evaluation of the histopathological characterization were taken on one group each at the of time 14, 21 and 28 days after transplantation respectively.

RESULTSTumors were found grown in the pyriform sinus of all 15 rabbits with a success implantation rate of 100%. Dysphagia, body weight loss, rhinorrhea and short of breath appeared in the rabbits 28 days after transplantation. The metastasis rates of deep cervical were 100% in all three groups. The metastasis rates of submandibular lymph nodes were 3/5, 4/5 and 5/5 in 14-day, 21-day and 28-day group respectively. The metastasis rates of paratracheal lymph nodes were 0, 4/5 and 5/5 in 14-day, 21-day and 28-day group respectively. There were opposite side lymph node metastasis of deep cervical, submandibular and paratracheal in 4, 3 and 5 rabbits on 14, 21 and 28 days after transplantation respectively. The median diameter for deep cervical, submandibular and paratracheal neck lymph nodes were 1.50, 0.60 and 0.0 cm in 14 days; 1.60, 0.80 and 0.50 cm in 21 days; 1.80, 0.8 and 0.65 cm in 28 days (P > 0.05).

CONCLUSIONSThe animal model for pyriform sinus carcinoma is established successfully. The metastasis of deep cervical lymph node could be induced from day 14 after VX2 transplantation.