Sialolithiasis is the most common glandular alteration, characterized by the deposition of a calcified tissue, sialolith, in the glandular structures. We report the case of a 65-year-old male patient who was diagnosed 1 month ago with high-grade villous tubular adenoma in the sigmoid colon and noticed a swelling in the buccal floor region. Clinically, there was an increase in volume in the left submandibular region, fixed, hardened, with a smooth surface, and painful on palpation. On intraoral examination, a nodular lesion was observed on the left oral floor, normochromic, firm, with a smooth surface. The clinical hypotheses were sialolith, metastasis, and salivary gland neoplasia. The tomographic sections showed the presence of a sialolith occupying the entire length of the duct, measuring approximately 4.8 × 1.3 cm. Excisional biopsy was performed and histopathologic analysis revealed a mineralized fragment compatible with a sialolith. The case has been under follow-up for 5 months without recurrence. Sialolithiasis is the most common glandular alteration, characterized by the deposition of a calcified tissue, sialolith, in the glandular structures. We report the case of a 65-year-old male patient who was diagnosed 1 month ago with high-grade villous tubular adenoma in the sigmoid colon and noticed a swelling in the buccal floor region. Clinically, there was an increase in volume in the left submandibular region, fixed, hardened, with a smooth surface, and painful on palpation. On intraoral examination, a nodular lesion was observed on the left oral floor, normochromic, firm, with a smooth surface. The clinical hypotheses were sialolith, metastasis, and salivary gland neoplasia. The tomographic sections showed the presence of a sialolith occupying the entire length of the duct, measuring approximately 4.8 × 1.3 cm. Excisional biopsy was performed and histopathologic analysis revealed a mineralized fragment compatible with a sialolith. The case has been under follow-up for 5 months without recurrence.