A glomangioma is a rare benign neoplasm, one of the morphological forms of a glomus tumor, originating from neuromyoarterial glomus bodies, which are very similar in function to smooth muscle cells1-4. The organization of glomus bodies as arteriovenous anastomoses around a central Sucquet-Hoyer canal allows them to act as a contractile neuromyoarterial receptor to control blood pressure and temperature by regulating peripheral blood flow, and to also control skin circulation2,5-7. Glomus bodies can be found throughout the human body but are most concentrated in the digits, palms, and soles of the feet, which is the reason that the most common and classic presentation of a glomus tumor is in the hand, especially in a distal phalanx1,2,4-6.
Patients with glomus tumors often present clinically with a triad of classic symptoms: (1) hypersensitivity to cold, (2) sudden attacks of severe pain, and (3) pinpoint tenderness to blunt palpation1-5. Although these symptoms are quite characteristic, many patients with glomus tumors do not present with this classic triad. In studies of many patients with glomus tumors, 63% to 100% presented with this triad of symptoms, the reported percentage depending on the center at which they were treated1,2,4,5,7.
Glomus tumors are benign but are notable due to their rarity and the common delay between presentation and diagnosis as well as the pain and associated decreased quality of life experienced by the patients3-5,8,9.
The following are descriptions of two patients who presented with glomus tumors that were atypically located in the knee region. For both of these patients, the diagnosis was complicated by the presence of other disorders in the area of the knee and by a lack of the classic triad of symptoms seen with glomus tumors. The patients were informed that data concerning the case would be submitted for publication, and they consented.
Case 1. A sixty-nine-year-old man was hospitalized in 1999 for severe discomfort in the right knee joint. Approximately eight years prior to hospitalization, the patient sustained an injury to the right knee, including trauma to the patella, which was treated with application of a cast. Three years after the injury, the patient experienced pain in the right knee. This pain was originally attributed to the injured patella.
During the physical examination, the right patella was painless, had normal mobility, and was not ballotable. The patient walked freely and without limping. Above the edge of the proximal medial quadrant of the patella, a soft mass that appeared bluish was visible. The mass was exquisitely tender to palpation.
At surgery, the mass was removed easily. It was bluish and measured 1 × 1 cm in size, with visible capillaries passing through it in a stellate arrangement (Fig. 1). The mass was found to be a glomangioma. The pain in the right knee resolved, and the patient has continued to be without symptoms for eight years.
Case 2. A forty-eight-year-old woman was hospitalized twice (five months apart) for severe pain and limited range of motion in the right knee. Three years earlier, she had twisted the knee and had been treated nonoperatively, after which she had had no relief of symptoms and required crutches to walk.
Physical examination revealed that the patient was obese (a body mass index of 35.2) and had limited range of motion of the right knee joint (from 20° to 80°). The skin over the painful area appeared normal. The patient limped on the right side with attempts at weight-bearing.
Radiographs of the right knee joint showed mild osteoarthritic changes (Ahlbäck score of I)10,11. During arthroscopy of the right knee, a diagnosis was made of degenerative damage to the posterior horn of the medial meniscus, International Cartilage Repair Society grade-II or III cartilage changes12 in the bearing surface of the medial condyle of the femur, and a degenerative tear of the anterior cruciate ligament at its femoral insertion. Shaving and microfractures of the damaged surface of the medial condyle of the femur were performed, and the damaged portion of the medial meniscus was removed. Postoperatively, the patient did not experience an appreciable change in symptoms.
The patient was evaluated again as a result of continued pain five months later. Palpation of the area of the tuberosity of the right tibia was difficult due to severe hyperesthesia.
An ultrasound examination of the right knee showed a slightly increased volume of joint fluid. A region with dimensions of 23 × 10 × 20 mm was observed medial to the tibial tuberosity (Fig. 2), and the ultrasound scan demonstrated multiple blood vessels in the surrounding area.
An excisional biopsy was performed, which revealed a highly vascular 1.5 × 2-cm mass on the medial side of the tibial tuberosity. The mass was bluish in color, had the consistency of jelly, and had visible blood vessels traversing it.
Histopathologic examination of the mass revealed it to be a glomangioma (Fig. 3). Immunohistochemical staining was performed with use of monoclonal antibodies to desmin and smooth muscle actin, and the results showed positivity for smooth muscle actin and desmin and negativity for chromogranin. All of these findings were consistent with a glomus tumor or glomangioma13.
Immediately after the operation, the pain disappeared, and a few days later the patient was walking freely without crutches. At the time of the last follow-up visit, six months postoperatively, the patient reported continued relief of pain.