[1] Karolinska Hosp, Dept Otorhinolaryngol Head & Neck Surg, S-17176 Stockholm, Sweden
[2] Karolinska Inst, Dept Oral Pathol, Stockholm, Sweden
[3] Karolinska Hosp, Dept Tumour Pathol, S-10401 Stockholm, Sweden
[4] Danderyd Hosp, Dept Tumour Pathol, Stockholm, Sweden