Faculty Bibliography

Benign extraosseous cartilage tumours of the hand and wrist comprise soft tissue chondromas, synovial chondromatosis and tenosynovial chrondromatosis. These tumours can significantly affect patients as they are often painful, functionally limiting and cosmetically displeasing. Although each tumour is generally considered to be a distinct entity, they share radiological and histopathological similarities. Occasionally, all three tumours may be seen in the same patient. This is an important consideration because of the risk of recurrence that may not necessarily occur at the same anatomical site but instead extend to different sites, such as a tendon sheath and/or joint

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is an unusual surface-based lesion of bone found most commonly in the hands and feet. In the original description of the lesion and in all publications that followed, one of the key imaging characteristics used to define this entity was the lack of cortico-medullary continuity with the underlying bone. The authors present 4 unique cases of pathologically proven BPOP in which cortico-medullary continuity with the underlying bone was demonstrated on imaging. It is believed that florid reactive periostitis, BPOP and turret osteochondroma may reflect points along the same continuum with trauma the likely inciting event. The authors suggest that, given this continuum, it may be possible to have BPOP lesions demonstrating overlapping imaging features with osteochondroma. If this is the case, strict adherence to the standard imaging criterion of lack of continuity between the lesion and the underlying bone may lead to misdiagnosis of these unusual cases of BPOP as osteochondromas

Extraskeletal osteosarcoma (ESOS) is a rare soft tissue sarcoma, typically characterized by high-grade histological features and a grave prognosis. However, 4 cases of well-differentiated ESOS with a better prognosis have been documented in the literature within the last 40 years. We report 2 additional cases, 1 with multicentric presentation and dedifferentiation, and we emphasize the histological features that are useful in distinguishing this lesion from other soft tissue tumors. Well-differentiated ESOS seems to represent a rare but distinct low-grade variant of ESOS. The limited published experience suggests that although the biologic behavior of this tumor is better than that of classical ESOS, there are cases with progression to a higher grade, leading eventually to final demise

PURPOSE: The purpose of this study was to review our experience with a benign surface bone lesion referred to as bizarre parosteal osteochondromatous proliferation (BPOP) or Nora's lesion, named for the pathologist who described it in 1983. The lesion may be confused with a variety of tumors, particularly solitary osteochondromas, which are rare. METHODS: The files in the Department of Pathology at the Hospital for Joint Diseases were reviewed over a 21-year period for all surface bone lesions involving the tubular bones in the hand. There were a total of 10 cases of BPOP compared with only a single case of an osteochondroma. RESULTS: Radiographs generally showed a well-marginated uniformly dense mass arising from the surface of the affected bone without any disruption in its bony architecture. Surgical excision is the definitive treatment and included the fibrous pseudocapsule over the lesion, any periosteal tissue beneath the lesion, and any area of the cortex of the host bone that appeared abnormal. Although in the medical literature the recurrence rate for BPOP is high, we had only one recurrence in our series. CONCLUSIONS: BPOP is a benign surface bone lesion that may be confused with benign and malignant tumors. Although there is a cleavage plane between the lesion and host bone, we recommend excising the pseudocapsule over the lesion, any periosteal tissue beneath the lesion, and decorticating any abnormal-appearing areas in the underlying host bone. This may explain the low recurrence rate in our series

Twelve cases of bizarre parosteal osteochondromatous proliferation (BPOP), also known as Nora's lesion, are reported. Ten lesions were located in the small bones of the hands, and 2 were located in long bones (femur and proximal tibia). Patient age ranged from 12 to 63 years (average, 30.3 years). Radiography of the lesions in the hand bones showed calcific masses attached to the underlying cortex, without interruption of the latter. The long bone lesions revealed unusual findings. In the femur, BPOP presented with extensive cortical destruction and was suggestive of a malignant lesion. This presentation has not been described to date. In the tibia, the lesion was located in the soft tissue without cortical attachment. This type of BPOP probably represents an immature lesion that over time will mature to solid cortical attachment. On histologic examination, all lesions demonstrated 3 distinct components with variable degrees of representation: (1) hypercellular cartilage with calcification and ossification, with the calcified cartilage having a characteristic basophilic tinctorial quality; (2) cancellous bone undergoing maturation; and (3) spindle cell stroma without cytologic atypia. In 1 case with a long-standing history, the cartilaginous component was minimal. BPOP, together with florid reactive periostitis and turret exostosis, may represent different stages in the development of a posttraumatic proliferative process. BPOP apparently arises from the periosteal tissues through a process of cartilaginous metaplasia

We report a case of a 14-year-old boy with an intracompartmental lytic lesion with poorly defined margins in the right distal tibia that was originally treated with curettage and bone grafting. Histologic examination showed an osteoblastic tumor with unusual features, which was found on consultation to be an osteoblastoma-like osteosarcoma, a rare, low-grade variant of osteosarcoma. Subsequently, the patient underwent en bloc resection of the distal tibia, which was replaced with vascularized bone graft and followed by chemotherapy. Two years later, he is alive with lung metastases

Multifocal osteosarcoma is uncommon. Long-term survival of an incompletely treated case is exceptional. We report an unusual case of bifocal sclerosing osteosarcoma in a 38-year-old women that involved the left ilium and right proximal femur. The femoral lesion was resected. The tumor in the left ilium was not treated. She did not receive chemotherapy and has been free of metastases for 7 years. Recently, growth of the pelvic osteosarcoma has resulted in vascular compression and edema of the lower extremity. The patient's alkaline phosphatase has been elevated throughout. The tumor was HMB-45 positive, which has not been previously reported in osteosarcoma. The pathogenesis of multifocal osteosarcoma is discussed

This article describes 11 cases of myxoid chondrosarcoma (MCS), with 10 arising in soft tissues and one developing in bone. Most of the tumors (six) were located in the lower extremities. Two lesions developed in the fingers, a previously unreported location for MCS. Four cases showed secondary bone destruction, which is a rare feature of this tumor. S100 protein was expressed by tumor cells in all the specimens. Four out of eight tumors studied by electron microscopy contained intracisternal microtubular structures. Two tumors showed areas of spindle cell proliferation that merged with the areas of typical myxoid pattern. The cells in these areas had fibroblastic/myofibroblastic features by electron microscopy and were found to express cytokeratin by immunohistochemistry. The concomitant expression of cytokeratin and S100 protein in the spindle cells suggests that they represent a less differentiated cartilaginous component with unusual features. The clinical significance of the presence of such spindle cell areas presently remains unknown. Although myxoid chondrosarcoma is a slow-growing tumor, it has a high potential for metastases. Four of 11 patients in this series developed metastases.