Transformation of Benign Giant Cell Tumor of Bone Into Epithelioid Angiosarcoma
In this article, we report a case of transformation of a benign giant cell tumor (GCT) of the calcaneus into an epithelioid angiosarcoma. The patient presented to our service in 2003 and was followed until 2014. Transformation occurred 11 years after curettage, cryotherapy, cementation, and a well-documented disease-free interval. Longitudinal radiographs, magnetic resonance imaging, and histopathology were evaluated by the same medical team.
There are only a few case reports and case series of malignancy associated with GCT of bone. To our knowledge, this case report is the first to describe an assessment of the transformation of a benign GCT of bone into an epithelioid angiosarcoma. Orthopedic surgeons, radiologists, oncologists, and pathologists should be aware of the potential for transformation of benign GCTs to high-grade sarcomas after a long disease-free interval.
Take-Home Points
- Malignant transformation of a benign GCT is extremely rare.
- It is difficult to distinguish between an early malignant transformation and an overlooked malignancy.
- The most common clinical presentation of transformation of GCT into malignancy is pain, often with swelling.
- Interval monitoring of GCTs may be necessary in patients with symptoms concerning for malignant transformation.
- Clinicians should maintain a high clinical suspicion for malignant transformation or late recurrence of GCT in a patient with new pain at the wound site.
Giant cell tumors (GCTs) of bone account for about 5% of all primary bone tumors in adults, with a predominance in the third decade in life.1 Clinically, GCT of bone often presents with pain, pathologic fracture, and/or soft- tissue expansion in the epiphysis of long bones. However, GCT of bone also has been reported in non-long bones, such as the talus and the calcaneus.2,3 Histologically, GCT of bone consists of neoplastic stromal cells, mononuclear histiocytic cells, and multinucleated giant cells that resemble osteoclasts.4 The radiologic appearance of GCT is often described as a lytic, eccentrically located bony lesion that extends near the articular surface in patients with closed physes. Many GCTs have aggressive radiologic features with possible extensive bony destruction and soft-tissue extension.
Although categorized as a benign lesion, GCT can be locally aggressive, with a variable local recurrence rate of 0% to 65%, depending on treatment modality and skeletal location. Given the aggressiveness of GCT of bone, recommendations for operative intervention include intralesional curettage with adjuvant therapy (eg, cryotherapy, phenol, argon beam, electrocautery) and placement of bone void fillers (eg, bone graft polymethylmethacrylate). Wide resection is recommended when the articular surface is no longer viable for reconstruction secondary to extensive destruction. Some authors have reported that surgical margin is the only risk factor in local recurrence,5,6 and thus complete resection may be needed for tumor eradication. In addition, about 3% of GCTs demonstrate benign pulmonary implants, which have been cited as cause of death in 16% to 25% of reported cases of pulmonary spread.7,8
The literature includes few reports of primary or secondary malignant transformation of GCT. Hutter and colleagues9 defined primary malignant GCT as GCT with sarcomatous tissue juxtaposed with zones of typical benign GCT cells. Secondary malignant GCT is a sarcomatous lesion at the site of a previously documented benign GCT. Secondary malignant GCT of bone histologically has been classified as a fibrosarcoma, malignant fibrous histiocytoma, or osteosarcoma transformation.10
Most malignant transformations of GCT of bone have been attributed to previous irradiation of the lesion.11,12 However, there are some case reports of benign bone GCT malignant transformation in situ without any other medical intervention. It was reported that non-radiation-induced secondary transformations occur relatively early after GCT treatment.13 During the early stages of tumor recurrence, however, it is difficult to distinguish between malignant transformation and primary disease overlooked as a result of sampling error.
We report a case of secondary malignant transformation of GCT of bone 11 years after surgical curettage, cryotherapy, and cementation without adjuvant radiation therapy. To our knowledge, this case report is the first to describe transformation of a nonirradiated benign GCT into an aggressive, high-grade epithelioid angiosarcoma, a very rare vascular bone tumor. The patient provided written informed consent for print and electronic publication of this case report.
Case Report
In July 2003, a 46-year-old woman presented with left heel pain of several months’ duration. Plain radiographs showed a nonaggressive-appearing lytic lesion of the superior aspect of the posterior calcaneal tuberosity with a small cortical incongruity along the superior margin of the lesion (Figures 1A-1D).
