A 14-Year-Old-Girl with Wrist Pain and Swelling

The biopsy contained predominantly fibrous tissue with admixed multinucleated osteoclast-like giant cells often centered on areas of stromal hemorrhage. Foci consistent with the cyst walls that line blood-filled cavities were also noted. A small amount of reactive woven bone was also present. These findings confirm the diagnosis of aneurysmal bone cyst (ABC). Following diagnosis, the patient underwent a second surgical procedure under regional anesthesia for definitive treatment with curettage, phenol adjuvant therapy, and distal radial autografting as well as allografting with demineralized bone matrix and cancellous chips (Fig. 7). The postoperative course required prolonged immobilization followed by ultrasound-mediated bone stimulation; however, 23 months following surgery, the left scaphoid demonstrated radiographic union and she had no pain and minimal limitation of range of motion clinically (Figs. 8 and 9).

Reference: Lebus GF, Cates JM, Lee DH. Aneurysmal bone cyst of the scaphoid: A case report. JBJS Case Connect. 2016 Jun 22;6(2):e49.

First described by Jaffe and Lichtenstein in 1942, ABCs are rare, benign skeletal tumors that affect patients early in life, usually in the first 2 decades. Although they may arise in any portion of the skeleton, the majority affect the femur, tibia, humerus, fibula, skull, and posterior elements of the spine. Most patients with ABC present with localized pain and soft-tissue swelling and occasionally a palpable, expansile mass. The classic appearance on radiographs is that of an expansile lesion with thinned cortices and often osseous septations. MRI reveals contrast-enhancing septa as well as fluid-fluid levels, which represent the layering of solid blood components within the cavity of the lesion. The pathophysiology of ABCs remains controversial. Some cases may represent a primary bone neoplasm, while others may be sequelae of traumatic injury; a vascular anomaly; or cystic degeneration of a precursor lesion, such as giant cell tumor of bone, osteoblastoma, osteosarcoma, chondroblastoma, nonossifying fibroma, or fibrous dysplasia, among other bone tumors. Although ABCs have a signature appearance radiographically and histologically, other lesions can have many of these characteristics as well. Fracture through a simple cyst, giant cell tumor, and telangiectatic osteosarcoma should remain in the differential diagnosis when assessing these lesions. In the case of our patient, the histopathologic diagnosis was made by virtue of the facts that the stroma is more fibrous in an aneurysmal bone cyst than in a giant cell tumor and that aneurysmal bone cysts lack the overt cytologic atypia and atypical mitotic activity seen in osteosarcoma.

The ideal treatment for aneurysmal bone cysts is also a matter of controversy because of a lack of prospective randomized controlled trials; however, the most common method consists of curettage with or without adjuvant therapy and bone-grafting. Excision has the lowest rate of recurrence but is often not practical given the anatomic location of the lesion. For lesions that are extensive and periarticular, resection and reconstruction or arthrodesis may be required. Treatment is not always straightforward, as the rate of local recurrence has been reported to be as high as 20% and malignant transformation, although rare, has been documented. Phenol adjuvant therapy, which was used in this case, has historically been believed to lead to decreased recurrence rates because of its necrotizing effect on residual tumor cells, although recent reports suggest that adequate intralesional curettage may be more predictive of decreased recurrence rates than use of any adjuvant therapy. Additionally, phenol and other adjuvant treatments may damage surrounding normal tissues and should be employed with discretion.

There are few reports documenting the existence of ABCs in the carpal bones, particularly the scaphoid. To our knowledge, there is only one prior study, in the French literature, of a similar occurrence in the scaphoid bone specifically. Platt and Klugman described a similar account of an ABC of the capitate in 1995 as well as documented a review of 32 previously reported cases of ABC of the hand. In that study, the majority (52%) of ABCs involved the metacarpals, followed by the phalanges (36%) and then the carpal bones (12%). Mankin et al. and Moussallem et al. documented 2 separate cases of ABC of the lunate. Whereas Mankin et al. performed an excision of the lunate and a scaphocapitate arthrodesis, Moussallem et al. treated their case by curettage and bone-grafting without excision or arthrodesis. Both methods achieved good clinical outcomes. Sakamoto et al. similarly successfully treated an ABC of the capitate without arthrodesis and obtained a good clinical outcome without recurrence.

In summary, this case report documents an uncommon but treatable cause of wrist pain in an otherwise healthy adolescent. Similar to other cases in the literature, our patient experienced resolution of the ABC of the scaphoid with curettage, phenol adjuvant therapy, and local autografting along with supplemental allograft. She did have a prolonged postoperative course in terms of osseous healing of the scaphoid, but nearly 2 years after treatment, she had no sign of recurrence and was clinically asymptomatic.

Reference: Lebus GF, Cates JM, Lee DH. Aneurysmal bone cyst of the scaphoid: A case report. JBJS Case Connect. 2016 Jun 22;6(2):e49.