Table 1.
Differential diagnosis of juvenile pleomorphic adenoma of the cheek
| Tumor | Salient histological features |
| Carcinoma ex pleomorphic adenoma | |
| Adenoid cystic carcinoma | - Cribriform and pseudoglandular patterns of basaloid cells with hyalinized stroma - Frequent perineural invasion - Minimal nuclear pleomorphism - No squamous differentiation - No high grade dysplasia or squamous carcinoma in situ, no extensive necrosis |
| Polymorphous low grade adenocarcinoma | - Uniform plump columnar cells with bland nuclei arranged in variable growth patterns (tubular, cribriform, papillary, solid, fascicular, microcystic, single file, pseudoadenoid cystic, strand-like, mixed) - Perineural invasion common around small nerves - Infiltrative borders |
| Basal cell adenoma | - Elongated and branching canaliculi separated by hyaline stroma |
| Acinic cell carcinoma | - Variable cell types (serous, clear, vacuolated, intercalated duct cells) arranged in solid, microcystic, papillary cystic and follicular patterns - few mitotic figures |
| Clear cell carcinoma-hyalinizing type | -Trabeculae, cords, islands or nests of monomorphic clear cells surrounded by hyalinized bands with foci of myxohyaline stroma |
| Cystadenocarcinoma | - Invasive, cystic growth pattern, 75% had - Conspicuous papillary component - Composed of small cuboidal cells, large cuboidal cells, tall columnar cells or mixture - Cystic spaces with hemorrhage and granulation tissue are frequent |
| Intraductal carcinoma | - intraductal neoplasm with micropapillary, cribriform, solid, comedo or clinging patterns, with preservation of myoepithelial cells surrounding intraductal tumor |
| Mucoepidermoid carcinoma | - Cords, sheets, clusters of mucous, squamous, intermediate and clear cells; low to high grade |
| Epithelial myoepithelial carcinoma | - Both epithelial and myoepithelial components seen - Most tumor cells have myoepithelial features with clear cytoplasm or naked nuclei - Focally, there are ducts or tubules with an outer rim of myoepithelial cells and inner, dark ductal cells with scant eosinophilic cytoplasm and round, bland nuclei |