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Chondroblastoma is a rare benign tumor of immature cartilage cells that generally occurs in an epiphyseal location of skeletally immature individuals. However, a few studies have reported cases in older patients. The purpose of this study was to evaluate the clinical, radiographic, and pathologic features of chondroblastoma in an adult population. The pathology archives of our institution were searched for cases of chondroblastoma diagnosed in patients ≥25 years of age. Of 14 patients identified, 8 were male and 6 were female with a median age of 34 years (range = 29-54 years). Most lesions occurred in short bones of hands and feet (N = 7, 50%), followed by the long tubular bones (N = 4, 28%). All demonstrated typical histologic features of chondroblastoma, but more extensive calcification, necrosis, and degenerative changes were also seen. At follow-up (median = 73.5 months), 2 patients (17%) had local recurrence. None had metastasis. In summary, chondroblastoma in adults tends to involve the short bones of the hands and feet and demonstrate histologic changes associated with long-standing growth of a benign tumor.

Chondromyxoid fibroma (CMF) is a relatively uncommon benign bone tumor of cartilaginous differentiation. The primary pitfall in the histopathologic diagnosis of CMF is confusion with a high-grade chondrosarcoma, owing to the atypical stellate and spindled cells set within a chondromyxoid background. CMF is particularly challenging to diagnose within the pelvis, where clinical suspicion for chondrosarcoma is high and benign lesions may grow to a large size to occupy the pelvic bones. In our practice, we noted this difficulty in several consecutive cases, especially when older patients presented with CMF within the pelvis. This prompted an institutional retrospective case review of all CMF within the pelvis. In 10 cases, we found overall that CMF of pelvis occurred in an older age range (mean age = 48.6 years), was larger in size (mean size = 6.0 cm), and showed a higher rate of soft tissue extension (50%) as compared with prior reports of nonpelvic CMF. Typical histologic features of CMF were seen in all cases; however, a high frequency of dystrophic calcification (50%) and necrosis (30%) was observed. Of interest, these aggregate demographic, radiologic, and histologic findings are all consistent with a benign neoplasm that has grown undetected within the pelvis over a long period of time. Recognition of these differences between pelvic CMF and tumors involving other sites will aid in avoiding misdiagnosis of this uncommon entity. [ABSTRACT FROM AUTHOR]

Abstract: Benign cartilage lesions can be divided into those that differentiate towards fetal type cartilage (chondroblastoma and chondromyxoid fibroma) and those that differentiate towards mature hyaline type cartilage (osteochondroma, chondroma). Nora lesion is a reactive periostitis that mimics osteochondroma and is discussed with this group of lesions. This article reviews their clinical, radiological and pathological features along with the main differential diagnoses. It also briefly reviews multiple osteochondromas, multiple enchondromas and Maffucci syndrome. [Copyright &y& Elsevier]