Surface-based chondroblastoma of the tibia: a unique presentation

Periosteal chondroblastoma of the femoral neck: two cases and a review of the literature

Chondroblastoma is a rare benign cartilaginous tumor mostly confined to the epiphyses and apophyses. Cases outside the epiphyseal region are exceedingly rare. Extramedullary chondroblastomas are exceptional; to our knowledge, only two cases qualified as "periosteal chondroblastoma" have been described in the literature. We report two cases of metaphyseal periosteal chondroblastoma both located on the inferior surface of the femoral neck. Both cases were paucicellular with an unusual dense sclerotic reaction. The diagnosis of chondroblastoma was supported by the expression of histone 3.3, K36M mutant in tumor cells.

Distal Femoral Non-Epiphyseal Cortical Chondroblastoma Confirmed with H3F3B p. Lys36Met Mutation

Background: Chondroblastoma is a primary bone tumor typically arising from the intramedullary space of the epiphysis or epimetaphysis. A non-epiphyseal chondroblastoma is uncommon. Case report: An 11-year-old girl presented with an eccentric cortical osteolytic lesion in the distal femur metaphysis. The typical morphology, diffuse H3.3 K36M immunohistochemical expression and H3F3B point mutation (c. 110A > T) unequivocally supported the diagnosis of chondroblastoma. Discussion: We described a non-epiphyseal cortical-based chondroblastoma involving the distal femur harboring the typical H3F3B mutation. Non-epiphyseal chondroblastoma may harbor the H3F3B mutation.

Metaphyseal chondroblastoma in a pediatric patient

Chondroblastoma is a rare, benign neoplasm usually located in the epiphyses and apophyses of the long bones in the immature skeleton. Radiologically, these tumors have a classic appearance of a lytic lesion with chondroid matrix surrounded by a thin sclerotic rim. Here, we describe the case of a 5-year-old male who presented with a chondroblastoma unusually located exclusively in the metaphyseal region, which led to an elusive diagnosis. The presence of tumors outlying the traditional location or epidemiological spectrum, along with the potential for histopathological misdiagnosis, can pose a diagnostic and therapeutic challenge for the treating team.

A report of an intracortical chondroblastoma of the diaphysis in a skeletally mature patient

Chondroblastomas characteristically occur in skeletally immature patients, and arise within the medullary canal of the epiphysis. We report a rare case of an intracortical chondroblastoma arising in the diaphysis, and occurring in an adult in his 3^rd decade of life. Immunohistochemistry results were critical to confirmation of this rare diagnosis, with immunohistochemistry showing S100, DOG1, and H3K36me3 positivity in the neoplastic cells.

Imaging of Pediatric Bone Tumors and Tumor-like Lesions

Bone lesions are commonly seen when reporting pediatric skeletal imaging. Distinguishing aggressive from nonaggressive lesions is essential in making the diagnosis. Not all aggressive lesions are neoplastic; indeed, osteomyelitis frequently presents with aggressive appearances and is far more commonly seen in the pediatric population than neoplastic lesions. In this article, we discuss an approach for the diagnosis of pediatric bone tumors and tumor-like conditions. The most common pediatric benign and malignant bone tumors are discussed in more detail.