Post-traumatic cystic bone lesions, also known as fracture cysts, are benign, transient post-fracture cysts, which are relatively uncommon and usually appear about one-to-two months after traumatic fracture.
They are rare but may be under recognised, as monitoring after fracture often is only clinically. They have most often been reported in children of growing age. The most common reported site is the distal radius 1-3.
Though mostly asymptomatic in nature, patients with these transient lesions can present with moderate soft swelling 1.
Characteristics of these lesions are:
- non-expansile cyst of <1 cm in diameter
- may be multiple
- close proximity to former fracture site
Typically encountered at about a month after initial fracture, they have been reported to occur as late as 18 months after the initial trauma 1.
There is ongoing debate whether these transient lesions represent intramedullary fat inclusions cysts (most accepted theory) or resorption cysts of excessive periosteal reaction caused by subperiosteal hematoma or intraosseous haemorrhage 1,3.
Typical appearances are that of a subcentimeter oval or round lucency without expansivity, peripheral condensation or periosteal reaction and close proximity to the site of former fracture.
Treatment and prognosis
As all hitherto reported lesions resolved spontaneously, no treatment is needed.
Encountering a cyst-like lesion close to a healing fracture (probably even greenstick fracture) can make the diagnosis straightforward. More challenging diagnostic scenarios, however, can comprise lack of former studies (or unawareness of their existence, unavailability at other institutions, etc), incomplete clinical information or a long period between initial fracture and lesion on actual imaging studies.
In those cases and in general differential diagnostic considerations may include:
- 1. Talawadekar GD, Muller M, Zahn H. Benign self-limiting cystic lesion after lower end radius fracture in a child. Indian J Orthop. 2009;43 (1): 99-101. doi:10.4103/0019-5413.45333 - Free text at pubmed - Pubmed citation
- 2. Dürr HR, Lienemann A, Stäbler A et-al. MRI of posttraumatic cyst-like lesions of bone after a greenstick fracture. Eur Radiol. 1997;7 (8): 1218-20. Pubmed citation
- 3. Asrian A, Shahabpour M, Tajdar F et-al. Posttraumatic cyst-like lesions of cortical bone in children. Acta Orthop Belg. 2010;76 (2): 264-8. Pubmed citation
- 4. Moore TE, King AR, Travis RC, Allen BC. Post-traumatic cysts and cyst-like lesions of bone. Skeletal radiology. 18 (2): 93-7. Pubmed
- 5. Lewandowski LR, Murphey MD, Potter BK. Posttraumatic cysts after pediatric fracture. Journal of pediatric orthopedics. 33 (3): 239-43. doi:10.1097/BPO.0b013e318280a63f - Pubmed
Related Radiopaedia articles
The differential diagnosis for bone tumours is dependent on the age of the patient, with a very different set of differentials for the paediatric patient.
- bone-forming tumours
- cartilage-forming tumours
- chondromyxoid fibroma
- juxtacortical chondroma
- fibrous bone lesions
- bone marrow tumours
- other bone tumours or tumour-like lesions
- aneurysmal bone cyst
- benign fibrous histiocytoma
- giant cell tumour of bone
- Gorham massive osteolysis
- haemophilic pseudotumour
- intradiploic epidermoid cyst
- intraosseous lipoma
- musculoskeletal angiosarcoma
- musculoskeletal haemangiopericytoma
- primary intraosseous haemangioma
- post-traumatic cystic bone lesion
- simple bone cyst
- impending fracture risk