Case Report: Submandibular plunging ranula secondary to sublingual gland venous vascular malformation

Venous vascular malformation of the sublingual gland is rare, and secondary submandibular plunging ranula has not been previously documented. Here we report a case of a 32-year-old man presenting with a painless, progressively enlarging mass in the right submandibular region for one month. No abnormalities were found in the oral floor. Preoperative ultrasonography and magnetic resonance imaging revealed a well-circumscribed oval mass measuring approximately 40 mm × 30 mm in the submandibular region, with a tortuous vascular isthmus (“tail sign”) extending from the posterosuperior aspect of the mass toward the sublingual space. The lesions demonstrated low signal on T1-weighted imaging and high signal on T2-weighted imaging. Contrast-enhanced T1 imaging highlighted the sublingual gland, the tortuous vascular isthmus, and the wall of the submandibular mass. Intraoperatively, the cyst, the sublingual gland, and the isthmus connecting them, were completely excised. The contents of the cyst were viscous, egg-white–like fluid. Hematoxylin-eosin staining revealed malformation-like proliferation of thin-walled vessels accompanied by hemorrhage or congestion within the sublingual gland and the outer layer of the cyst wall. Immunohistochemistry showed positive expression of CD31 and CD34 and negative expression of D2-40 in both the sublingual gland and the outer layer of the cyst wall, supporting a blood vascular (non-lymphatic) endothelial phenotype; VEGF expression was also observed. Clinicopathological diagnosis was a case of venous vascular malformation with plunging ranula of the sublingual gland. The patient recovered uneventfully without complications, and no recurrence was observed during 54 months follow-up. We hypothesize that the venous vascular malformation contributed to ranula formation, although temporal causality cannot be established from a single case.