Intratumoral sympathetic nerves in human salivary ACC. (A) ACC (T) intratumoral innervation and normal salivary gland (N). Immunostaining of sympathetic (TH), parasympathetic (VIP) nerves, and NFH for all nerves. Scale bar: low power, 20 μm; and high power, 50 μm. (B) Different innervation patterns between salivary ACC and normal acini. ACC: Disorganized intratumoral TH⁺ nerves located between the cribriform areas. Normal acini: Small-caliber, dot-like TH⁺ and VIP⁺ nerves encircle normal salivary acini. Tubb3 is a pan-neuronal marker. Scale bar: 50 μm. (C) TH⁺ nerve sprouts innervate ACC. ACC: Small-caliber TH⁺ nerves (arrowheads) arise from adjacent large-caliber TH⁺ nerves (dashed circles). Normal: No sprouts arise from large-caliber nerves (dashed circles). Tubb3 is a pan-neuronal marker representing all nerves on adjacent sections. Scale bar: low power, 200 μm; and high power, 50 μm. (D and E) IF and H&E staining of intratumoral TH⁺ nerves (D) and quantification (E) in salivary ACC (n = 10), normal salivary acini and hilum (n = 9), polymorphous adenocarcinoma (n = 3), mucoepidermoid carcinoma (n = 5), myoepithelial carcinoma (n = 4), acinic cell carcinoma (n = 8), and pleomorphic adenoma (n = 5). (A–D) Representative images from digitized whole-slide scans of composite 20× stitched images. Scale bar: 100 μm. P values were determined by one-way ANOVA and Fisher’s least significant difference (LSD) test. **P < 0.01, ***P < 0.001, ****P < 0.0001, ns: not significant.