Specific Characteristic of Hyperplastic Callus in a Larger Cohort of Osteogenesis Imperfecta Type V

Hyperplastic callus (HPC) is the most conspicuous features of osteogenesis imperfecta (OI) type V, of which accurate diagnosis and treatment are facing challenges. We investigate the clinical features, and impact factors of HPC in OI type V patients. In this retrospective single-center study, a total of 21 patients with type V OI confirmed by IFITM5 mutation were included. Radiological characteristics of bone were evaluated by X-rays, dual-energy X-ray absorptiometry, and computed tomography scan. Bone biopsy specimens were performed and stained by routine hematoxylin-eosin. The effects of bisphosphonates on HPC were investigated. Eleven patients (52.3%) had HPCs at 19 skeletal sites, 11 of which affected the femur. Three patients developed four (21.1%) HPCs after fractures, and 15 (78.9%) HPCs occurred in absence of bone fracture. The progress of HPCs was variable, of which most HPCs enlarged in the initial phase and remained stable, and only one HPC dwindled in size. One patient had a rapidly growing mass on the right humerus, and biopsy showed irregular trabeculae of woven bone and immature bone and cartilage in the loose and edematous collagenous network without signs of tumor. Bisphosphonates treatment had no significant effects on HPC of OI patients. HPC is the specific characteristic of OI type V patients, and its location, shape, size, and progression are variable, and the femur is the most frequently involved site. It is very important to make a diagnosis of HPC through detecting IFITM5 mutation and completing pathological diagnosis if necessary. The treatment of HPC is worth further exploration.

Late onset hyperplastic callus formation in osteogenesis imperfecta type V simulating osteosarcoma-A case report

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Hyperplastic callus formation is a very rare complication of osteogenesis imperfecta type V.

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The most important differential diagnosis is malignant osteosarcoma.

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A biopsy is the only way to distinguish between those two conditions.

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The underlying pathophysiology is still unknown and there is no causal therapy.

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A multidisciplinary approach in diagnosis and therapy is mandatory.

Introduction

We report a case of late onset hyperplastic callus formation (HPC) in the right femur in type V osteogenesis imperfecta (OI) mimicking the occurrence of a malignant osteosarcoma.

Presentation of case

A 27-year-old female patient consulted us due to swelling in her right femur over 2–3 months without trauma. X-rays looked like an osteosarcoma, blood tests showed increased bone metabolism. A CT scan, a MRI and biopsy were performed, showing late onset HPC due to osteogenesis imperfecta type V.

Discussion

OI shows a heterogeneous disease pattern due to a variety of clinical and radiographic findings. HPC is a rare complication of OI type V. Differential diagnosis range from cortical or periosteal osteosarcoma, periostitis, myositis ossificans, subperiosteal hematoma secondary to trauma or osteomyelitis.

Conclusion

Recognition of HPC as a form of this particular type of OI is important to avoid misdiagnosis like malignant transformation to osteosarcoma. A biopsy and advanced imaging modalities like CT, MRI and scintigraphy are recommended.

Expanding the phenotypic spectrum of osteogenesis imperfecta type V including heterotopic ossification of muscle origins and attachments

Background

Osteogenesis imperfecta (OI) is a clinical and genetic heterogeneous group of connective tissue disorders, characterized by bone fragility and a propensity to fracture.

Methods

In this report we describe the clinical phenotype of two patients, a 28‐year‐old woman and her mother (54 years old), both with a history of short stature and multiple fractures.

Results

Exome sequencing revealed the recurring IFITM5:c.‐14 C>T variant causing OI type V. Both patients had several fractures during childhood. CT‐scan and scintigraphy showed ossification of the origin and attachment of muscles and hypertrophic callus formation.

Conclusion

Ossification of the origin and attachment of muscles seems to be part of the phenotype in patients with OI type V.

IFITM5 mutations and osteogenesis imperfecta

Interferon-induced transmembrane protein 5 (IFITM5) is an osteoblast-specific membrane protein that has been shown to be a positive regulatory factor for mineralization in vitro. However, Ifitm5 knockout mice do not exhibit serious bone abnormalities, and thus the function of IFITM5 in vivo remains unclear. Recently, a single point mutation (c.-14C>T) in the 5' untranslated region of IFITM5 was identified in patients with osteogenesis imperfecta type V (OI-V). Furthermore, a single point mutation (c.119C>T) in the coding region of IFITM5 was identified in OI patients with more severe symptoms than patients with OI-V. Although IFITM5 is not directly involved in the formation of bone in vivo, the reason why IFITM5 mutations cause OI remains a major mystery. In this review, the current state of knowledge of OI pathological mechanisms due to IFITM5 mutations will be reviewed.