An extremely rare case of a glomus tumor in the popliteal fossa.

Glomus tumors are the benign perivascular tumors that typically present with hypersensitivity to cold, paroxysmal severe pain, and pinpoint tenderness. This tumor is usually subungual lesions and accounts for 1.6% of all soft-tissue tumors. However, extradigital glomus tumors are extremely rare and can be difficult to diagnose, as they typically have a diameter of less than about 1 cm. We report a glomus tumor in the popliteal fossa of a 17-year-old male patient who experienced severe posterior knee pain while playing sports. A physical examination did not reveal a mass, although a glomus tumor was identified in the popliteal fossa using magnetic resonance imaging. We successfully performed open excision to remove the tumor, and the patient achieved a restored postoperative gait and could perform sports activities with no pain. These tumors are extremely rare in the knee area, and typically have a diameter of less than about 1 cm, which can complicate their diagnosis and treatment, despite the presence of severe pain. Therefore, we recommend that clinicians be aware of extradigital glomus tumors, as careful imaging can facilitate an early diagnosis and treatment.