Differential diagnostic value of "blue reticulated chondroid-like material" in aneurysmal bone cysts: a classic histopathologic analysis of 215 cases.

OBJECTIVES: Our classic histopathologic study of aneurysmal bone cyst (ABC) revealed that "blue reticulated chondroid-like material" (BRC) is characteristic of ABC. METHODS: The light microscopic findings were retrospectively analyzed in 215 cases of ABC, including 101 primary and 114 secondary cases. In addition, 22 cases of telangiectatic osteosarcoma (TOS) were drawn from the same source and used as a control. RESULTS: We found the presence of typical BRC in 24 (23.8%) of 101 cases of primary ABC and in six (5.3%) of 114 cases of secondary ABC, with an overall incidence of 30 (14%). None of the cases of TOS showed BRC. BRC was significantly more common in primary ABC than in secondary ABC (P < .05) and in patients 19 years or younger than in those 20 years or older (P < .05). CONCLUSIONS: BRC appears to be a unique histopathologic feature of ABC, making it valuable to differentiate benign ABC from TOS. Simple H&E stain can be economically performed anywhere.

Difficulty distinguishing benign notochordal cell tumor from chordoma further suggests a link between them.

BACKGROUND: Much discussion about benign notochordal cell tissue in vertebrae has centered on the nature of its relationship, if any, to chordoma. Often referred to as benign notochordal cell tumors (BNCTs), these lesions have unique morphological features, however, differentiating between notochordal cells in discs, BNCT, and chordoma can be difficult. They are described as radiologically distinct from chordoma, with lysis, contrast enhancement, and a soft tissue mass indicating chordoma. METHODS: All chordomas diagnosed at our institution, the Istituto Ortopedico Rizzoli (Bologna, Italy), prior to 2008 were reviewed, yielding 174 cases. Five were limited to bone; one was a recurrent chordoma without original data available. The remaining four were re-evaluated in detail. RESULTS: There were three women and one man, aged 33-57 years (mean, 48 years). Two were BNCTs and two were mixed lesions containing BNCT and chordoma. On computed tomography, all were radiopaque with areas of lysis. One BNCT was heterogeneous on magnetic resonance imaging, enhancing after contrast. Microscopically, one BNCT had a well-defined cystic area with a sclerotic border. The other had a minute atypical area; it recurred as chordoma. The mixed lesions had areas of definitive BNCT, definitive chordoma, and atypical areas that did not meet the criteria for either. The atypical areas in all three cases 'blended' with areas of chordoma or BNCT. CONCLUSION: These cases illustrate the ongoing challenges in differentiating between BNCT and chordoma. All had unique imaging features; three had atypical microscopic areas blending with BNCT or chordoma, strengthening the argument for a relationship between the two entities and supporting the idea that some BNCTs may progress to chordoma. Our study dispels the notion that any single radiologic criterion used to distinguish between chordoma and BNCT is reliable, opening the discussion as to whether or how to monitor BNCTs.

Painful metal-on-metal total hip arthroplasty.

Two patients were evaluated for the possibility of hypersensitivity to a Metasul articulation (Centerpulse, Austin, Tex) coupled with total hip arthroplasty. Serum was tested with a lymphocyte proliferation assay, and the capsular tissues from the hip were examined for perivascular lymphocytes. The diagnosis of hypersensitivity to Metasul could not be confirmed in these patients, and ultimately, the painful hip arthroplasties were felt to be caused by a combination of musculoskeletal problems.

Pseudoanaplastic tumors of bone.

OBJECTIVE: To discuss the concept of pseudoanaplastic tumors of bone, which pathologically show hyperchromatism and marked pleomorphism with quite enlarged, pleomorphic nuclei, but with no to extremely rare, typical mitoses, and to propose guidelines for their diagnosis. DESIGN AND PATIENTS: From a database of 4,262 bone tumors covering from 1971 to 2001, 15 cases of pseudoanaplastic bone tumors (0.35% of total) were retrieved for clinical, radiographic and pathologic review. Postoperative follow-up after surgical treatment was at least 3 years and a maximum of 7 years. RESULTS: There were eight male and seven female patients. Their ages ranged from 10 to 64 years with average of 29.7 years. Pathologic diagnoses of pseudoanaplastic variants of benign bone tumors included: osteoblastoma (4 cases), giant cell tumor (4 cases), chondromyxoid fibroma (3 cases), fibrous dysplasia (2 cases), fibrous cortical defect (1 case) and aneurysmal bone cyst (1 case). Radiography of all cases showed features of a benign bone lesion. Six cases, one case each of osteoblastoma, fibrous dysplasia, aneurysmal bone cyst, chondromyxoid fibroma, giant cell tumor and osteoblastoma, were initially misdiagnosed as osteosarcoma. The remaining cases were referred for a second opinion to rule out sarcoma. CONCLUSIONS: Despite the presence of significant cytologic aberrations, none of our cases showed malignant behavior following simple curettage or removal of bony lesions. Our observation justifies the concept of pseudoanaplasia in some benign bone tumors as in benign soft tissue tumors, especially in their late evolutionary stage when bizarre cytologic alterations strongly mimic a sarcoma.

Pigmented villonodular synovitis of the foot and ankle.

BACKGROUND: Pigmented villonodular synovitis (PVNS) is a rare disease of uncertain etiology usually affecting the synovium of weightbearing joints. METHODS: We retrospectively evaluated 11 patients who were diagnosed and treated for PVNS of the ankle and foot over a 13-year period with a minimum of 2-year followup. Four patients with ankle joint PVNS and one patient with PVNS of the fifth metatarsophalangeal joint were seen initially at our institution and were treated with surgery alone. Six patients with ankle joint PVNS were referred to our institution for recurrent PVNS lesions; two of these patients were treated with excision alone, and the other four patients had surgical excision followed by radiation therapy with dosages ranging from 3600-4000 cGy. RESULTS: No recurrence was noted at a mean followup of 9 years for primary lesions and 3.5 years for recurrent lesions. CONCLUSION: Based on these results, surgical excision of primary lesions and excision with postoperative radiation for recurrent lesions are recommended.

Desmoid tumor of bone with enchondromatous nodules, mistaken for chondrosarcoma.

Desmoid tumor of bone, also termed desmoplastic fibroma or aggressive fibromatosis, is a rare, locally aggressive fibroblastic tumor. We present a 16-year-old male with a huge desmoid tumor involving the iliac wing. It was associated with enchondromatous nodules mimicking malignancy. The tumor in this patient was mistaken for chondrosarcoma and hemipelvectomy was performed. To our knowledge, such a case has not previously been documented fully in the English literature. The radiographic and pathologic findings and a possible mechanism of enchondromatous nodule formation in fibrous bone tumors are discussed.