Unusual solid submucosal angioleiomyoma of the upper lip: A case report and review of the literature.

RATIONALE: Angioleiomyoma (ALM) is a rare benign tumor originating from smooth muscle tissue, and its occurrence in the oral cavity is extremely uncommon. Although a few cases involving the upper lip have been reported, most lesions are exophytic or superficially located. Here, we report an unusual solid, submucosal ALM in the upper lip, highlighting its distinctive clinical, imaging, and histopathological features. PATIENT CONCERNS: A 43-year-old male presented with a firm, painless swelling in the upper lip that had gradually enlarged over the past 8 months. The lesion measured 4.0 × 2.0 cm, was located in the submucosa, and exhibited no overlying mucosal changes, which made clinical detection challenging. DIAGNOSES, INTERVENTIONS, AND OUTCOMES: Contrast-enhanced computed tomography demonstrated a well-defined submucosal mass with multiple calcifications. Histopathology classified the tumor as the solid subtype of ALM, showing interlacing bundles of smooth muscle cells surrounding vascular channels, with smooth muscle actin and desmin positivity and S-100 negativity. Complete surgical excision was performed under general anesthesia. The postoperative course was uneventful, and no recurrence was observed during 6 months of follow-up. LESSONS: This case highlights the importance of including ALM in the differential diagnosis of deeply seated upper lip masses. Awareness of its clinical and histopathological characteristics can aid in early diagnosis and appropriate management.