Neonatal osteofibrous dysplasia: Synchronous tibial and fibular involvement is common

Osteofibrous dysplasia is a rare non-malignant fibro-osseous bone tumour, first described and characterised under this name by Campanacci (1976). It is most commonly encountered in the tibia of children and young adults, but less frequently seen in the neonate with only few prior reports in the literature. We report a case of neonatal congenital osteofibrous dysplasia, presenting with unilateral limb deformity at birth. Radiographs demonstrated well-defined mixed lytic-sclerotic lesions, in a previously unreported distribution in this age-group, confined to the distal metadiaphysis of the affected tibia and fibula. Open surgery was performed for deformity correction, with tissue biopsy confirming the radiographically-suspected diagnosis. We present the up-to-date clinical, radiological, and pathological findings in this case of a rare pathology with some novel features, within this age group, in disease distribution and consequent radiographic appearances. OFD should be considered in the differential of similar congenital deforming bone lesions of the lower limb. We also review the small number of previously published cases of congenital OFD in the neonate, noting in particular that the frequency of ipsilateral fibular involvement appears to be higher than that observed in older patients.

Increased uptake of 68Ga-DOTA-FAPI-04 in bones and joints: metastases and beyond

Purpose: To describe the uptake of 68Gallium-labelled fibroblast activation protein inhibitor (68Ga-FAPI) in bones and joints for better understanding of the role of 68Ga-FAPI PET in benign and malignant bone lesions and joint diseases. Methods: All 129 68Ga-FAPI PET/MR or PET/CT scans from June 1, 2020 to February 20, 2021 performed at our PET centre were retrospectively reviewed. Foci of elevated 68Ga-FAPI uptake in bones and joints were identified. All lesions were divided into malignant and benign disease. Benign lesions included osteofibrous dysplasia, periodontitis, degenerative bone diseases, arthritis, and other inflammatory or trauma-related abnormalities. The number, locations and SUVmax of all lesions were recorded and analysed. Results: Elevated uptake of 68Ga-FAPI in/around bones and joints were found in 82 cases (63.57%). A total of 295 lesions were identified, including 94 (31.9%) malignant lesions (all were metastases) and 201 (68.1%) benign lesions. The benign lesions consisted of 13 osteofibrous dysplasia, 48 degenerative bone disease, 33 periodontitis, 56 arthritis, and 51 other inflammatory or trauma-related abnormalities. Spine, shoulder joint, alveolar ridge, and pelvis were the most commonly involved locations. Bone metastases were mainly distributed in the spine, pelvis and ribs. Among benign diseases, periodontitis and arthritis are site-specific. The mean SUVmax of bone metastases was significantly higher than that of benign diseases (7.14 ± 4.33 vs. 3.57 ± 1.60, p < 0.0001), but overlap existed. The differences in SUVmax among subgroups of benign diseases were statistically significant (p < 0.0001), with much higher uptake in periodontitis (4.45 ± 1.17). Conclusion: 68Ga-FAPI accumulated in both bone metastases and some benign diseases of bones and joints. Although the uptake of 68Ga-FAPI was often higher in bone metastases, this finding cannot be used to distinguish between benign and malignant lesions.

Osteosarcoma arising in a case of osteofibrous dysplasia of tibia with classic adamantinoma: A case report and literature review

A five-year-old boy presented with left tibial swelling; there was a typical radiological feature of osteofibrous dysplasia. He was observed until the age of 14 years; there was development of aggressive radiological features. Biopsy revealed chondroblastic osteosarcoma. It was excised and the histology revealed chondroblastic osteosarcoma. A small lesion distal to the main tumour revealed adamantinoma within a background of feature of osteofibrous dysplasia. Proximally, feature of osteofibrous dysplasia was identified focally. The finding of adamantinoma over the distal part of the lesion supports that feature of osteofibrous dysplasia may be a precursor of adamantinoma. They may be a spectrum of diseases with multistep neoplastic transformation. The osteosarcoma may be a result of de-differentiation from adamantinoma. This case is remarkable as the patient was only 14 years old and the tumour showed typical features of osteosarcoma, with feature of osteofibrous dysplasia and adamantinoma found in the same specimen. Feature of osteofibrous dysplasia may be a precursor of adamantinoma, and adamantinoma may dedifferentiate into osteosarcoma.