Expression of TWIST and SNAI1 nuclear transcription factors in pharyngeal squamous cell carcinoma. Positive (A) and negative (B) epithelial TWIST immunostaining in squamous epithelial cells (immunoscores 3/5 and 0/5, respectively). Positive stromal TWIST staining in stromal spindled cells (C; immunoscore 4/5). Positive SNAI1 immunostaining in the spindled stromal cells (D; immunoscore > 30 cells). Tumors A and D are moderately differentiated (grade 2/3) and tumours B and C poorly differentiated (grade 3/3). The stages are IV (A), II (B), IV (C) and IV (D). (Original magnifications of x100 in low power views and × 400 in the inserts).