Primary Aneurysmal Bone Cyst of the Phalanx

An aneurysmal bone cyst (ABC) is a benign tumor of bone that constitutes less than 2% of all bone tumors. Among these, less than 5% of ABCs occur in hand.[1] ABC occurs in the first two decades of life, the second decade being the most common. Most studies find the incidence equal in both sexes; however, some studies found a slight female preponderance.

We report a 5-year-old girl who came with a swelling in the left ring finger for 3 months. The swelling gradually increased in size for 3 months. The child did not have any pain in the region of the swelling. There was no history of trauma. On examination, we found a nontender diffuse, oval swelling of approximate size 6 4 cm involving the proximal phalanx of the ring finger. The range of movement in the ring finger was normal. Radiographs ([Fig. 1]) showed a solitary, fusiform, and osteolytic lesion involving the diaphysis, metaphysis, and distal epiphysis. We also noted cortical thinning, trabeculations in the lesion matrix, and a narrow zone of transition. Additionally, we found focal cortical destruction with no periosteal new bone formation.

Fig. 1 (A, B) Radiographs showing solitary fusiform, osteolytic lesion in the proximal phalanx. Cortical thinning, trabeculations in matrix, and narrow zone of transition are seen.

Intraoperatively, we found a honeycomb-like mass with blood-filled cavities and a thin, fragile cortex involving the middle and distal third of the proximal phalanx. We did not find any soft tissue infiltration. We curetted the mass entirely and stabilized the proximal phalanx with two Kirschner wires for stability. The histopathological examination revealed multiple cavernous areas lined with fibrous tissue and filled with blood, confirming an ABC. Soon after the surgery, we started the child with a partial range of movements and removed the Kirschner wire at 6 weeks. The child regained full range of movements, and we followed her with regular interval radiographs looking for recurrence of lesions. At the 2-year follow-up, the radiographs ([Fig. 2]) showed intact cortices of the proximal phalanx, with bone filling up most of the cavity created by the curettage. The child had a full range of movements with no foreshortening of the digit compared with the contralateral side.

Fig. 2 (A, B) Radiograph at 2 years postoperative follow-up showing all cortices of proximal phalanx to be intact, with bone growth partially filling the void.

Treatment of ABC focuses on local tumor control. Currently, surgical intervention is the standard of care over other modalities such as intralesional sclerotherapy and radiation therapy. Intralesional curettage and bone grafting are the most commonly done procedure; however, it is associated with a higher chance of recurrence.[2] The use of adjuvants like a high-speed burr, liquid nitrogen, phenol, or polymethyl methacrylate has decreased recurrence rates.[2] However, using a high-speed burr accurately is technically challenging in the small bones of the hand, where insufficient bone stock is left after curettage and poses a greater risk to soft tissue damage and joint penetration. The use of liquid nitrogen increases the risk of infection, fracture, and joint collapse. The use of cryosurgery in hand causes premature physeal closure due to thermal injury. Some authors recommend more radical treatment, including en bloc resection[3] and strut bone grafting.[4] [5] These are associated with lesser rates of recurrence; however, they are associated with higher morbidity.

Published results of the treatment of ABC in hand exclusively are scarce. Considering the technical difficulties of dealing with small bones of the hand in a child and the desire to preserve the growth plate, we decided to curette the entire lesion. Bone grafting was not done to avoid donor site morbidity. We believe the use of Kirschner wires instead of conventional postoperative immobilization in a cast/slab is superior. It allows for the mobilization of adjacent joints, thereby preventing joint stiffness.

An ABC occurring in the bones of the hand is a rare entity and involves the metacarpals or proximal phalanges. We found curettage and Kirschner wires stabilization without additional bone grafting to be a viable option in treating ABC of the phalanx in a child.

Consent

Informed consent of the parents of the child was obtained for the case report to be published.

Publication History

Article published online:
24 September 2021

• References

• 1 Athanasian EA. Aneurysmal bone cyst and giant cell tumor of bone of the hand and distal radius. Hand Clin 2004; 20 (03) 269-281 , vi
• 2 Başarir K, Pişkin A, Güçlü B, Yildiz Y, Sağlik Y. Aneurysmal bone cyst recurrence in children: a review of 56 patients. J Pediatr Orthop 2007; 27 (08) 938-943
• 3 Song KS, Lee SW, Bae KC, Sohn III ES. Aneurysmal bone cyst involving the metacarpal bone in a child. Am J Orthop 2015; 44 (03) E68-E70
• 4 Pallapati SC, Thomas BP, Anderson GA. En bloc excision and matched metatarsal transfer for expansive benign osteolytic lesions of the metacarpal. J Hand Surg Am 2016; 41 (11) e417-e423
• 5 Zaidenberg EE, Farias Cisneros E, Miller R, Zaidenberg CR. Metacarpal aneurysmal bone cyst en bloc resection reconstructed with osteoarticular allograft. J Hand Surg Am 2019; 44 (05) 425.e1-425.e5