Chondromyxoid fibroma (CMF) is the least common benign cartilaginous tumor, comprising less than 0.5 to 1% of all skeletal neoplasms. This subject was a 16-year-old female with a three-year history of pain involving the distal femoral metaphysis. This case showed an unusual feature: it was intracortical in location. Radiologic differential diagnosis included metaphyseal fibrous defect, periosteal chondroma, simple or aneurysmal bone cyst, and cortical abscess. On operation, the lesion filled the intracortical defect with whitish myxoid soft tissue, bulging into the adjacent soft tissue. Microscopically, it showed typical features of chondromyxoid fibroma composed of mainly myxoid nodules and peripheral fibrous elements with focal chondroid differentiation.
Adolescent ; Case Report ; Chondroblastoma/pathology/*radiography ; Female ; Femoral Neoplasms ; Human

Chondroblastoma is a rare benign bone tumor. It commonly affects the epiphysis of long bones during the second and third decades of life. Chondroblastoma of the temporal bone is extremely rare. We reviewed five cases of chondroblastoma arising in the temporal bone. Four cases were female and one was male. The ages ranged from 41 to 60 years (mean, 53.6 years). All cases involved the temporal bone. Three involved the left side and two the right. Chief complaints were long-standing localized pain and hearing difficulty. A sharply demarcated lobulated mass was the main radiological finding. Microscopic findings were those of chondroblastoma of usual locations. Two cases showed aneurysmal bone cyst-like areas. Immunohistochemical studies for CD34, CD99, S-100 protein and cytokeratin were performed. Tumor cells were diffusely positive for S-100 protein in three cases and weakly positive for cytokeratin in one case. CD34 and CD99 were negative in all cases. In summary, chondroblastoma of the temporal bone is rare and occurs in older age group than reported cases of chondroblastoma of the usual location in the literature.
Adult ; Bone Neoplasms/therapy ; Bone Neoplasms/diagnosis* ; Case Report ; Chondroblastoma/therapy ; Chondroblastoma/diagnosis* ; Female ; Follow-Up Studies ; Human ; Male ; Middle Age ; Temporal Bone/radiography* ; Temporal Bone/pathology*

Chondroblastoma ; pathology ; Chondrosarcoma ; diagnostic imaging ; pathology ; Chondrosarcoma, Mesenchymal ; pathology ; Diagnosis, Differential ; Female ; Hamartoma ; pathology ; Humans ; Lung Neoplasms ; diagnostic imaging ; pathology ; Middle Aged ; Radiography

OBJECTIVETo study the clinical, pathologic and radiologic features of chondroblastoma occurring in sites other than epiphysis and apophysis of long bones, and to investigate possible reasons for misdiagnosis.

METHODSThe clinical, pathologic and radiologic data of 18 chondroblastoma cases occurring in atypical sites were collected from 5 major hospitals in Shanghai during the past 12 years. S-100 immunostaining was performed to confirm the cartilaginous differentiation of the tumor cells.

RESULTSChondroblastoma occurred in small bones of feet in 10 of the 18 cases (55.6%) studied, being commonest in the talus and calcaneus bones. Mean age of the patients was 27.8 years, with 55.6% over 25 years of age. Radiologic examination revealed expansive, multilocular and well-demarcated radiolucent lesions in most cases. There was local cortical destruction in 5 cases (28%) and soft tissue infiltration in 1 case. In 10 cases (55.6%), the tumor was associated with aneurismal bone cyst or simple bone cyst formation. None of the cases studied was accurately diagnosed clinically before the operation. In 2 cases, the pathology was also misdiagnosed, often being diagnosed as aneurismal bone cyst or giant cell tumor.

CONCLUSIONSChondroblastoma occurring in atypical sites are often associated with atypical age, radiologic features and pathologic findings at presentation. Thorough understanding of the potential pitfalls is essential in order to avoid misdiagnosis.

Adolescent ; Adult ; Bone Cysts, Aneurysmal ; diagnosis ; diagnostic imaging ; pathology ; Bone Diseases ; diagnosis ; diagnostic imaging ; pathology ; Bone Neoplasms ; diagnosis ; diagnostic imaging ; pathology ; Calcaneus ; Child ; Chondroblastoma ; diagnosis ; diagnostic imaging ; pathology ; Diagnostic Errors ; Female ; Giant Cell Tumor of Bone ; diagnostic imaging ; pathology ; Humans ; Male ; Radiography ; Talus