Solitary synovial osteochondroma.

Solitary synovial osteochondroma (SSO) is a rare variant of extraskeletal osteochondroma. The aim of this study was to review 5 cases of SSO, including clinical, radiographic, and histopathologic features. Five cases of SSO were retrieved from our files. Histopathologic and radiographic findings were reviewed, and a clinicopathologic correlation was performed. Patients' ages ranged from 33 to 63 years. Knee mass was the most common presentation. All cases were well circumscribed and had multiple cartilaginous lobules surrounded by fibroadipose tissue. Microscopically, lobulated adult-type hyaline cartilage with central calcification was noted. Cytologic atypia was present in one case, but malignant features were absent. Two cases were suggestive of chondrosarcoma on imaging studies. Patients underwent surgery, which was curative in cases for which follow-up was available. In conclusion, SSO is a rare lesion that may mimic low-grade chondrosarcoma at times. Correct recognition of SSO depends on radiographic and clinicopathologic analysis.

Anaplastic thyroid cancer evolved from papillary carcinoma: demonstration of anaplastic transformation by means of the inter-simple sequence repeat polymerase chain reaction.

BACKGROUND: In thyroid tumors, the coexistence of well- and poorly differentiated tumor types has led to the hypothesis that poorly differentiated thyroid tumors develop from well-differentiated thyroid tumors. By evaluating the genomic instability of histologically distinct but coexisting tumor foci, this study aimed to develop an improved understanding of thyroid tumorigenesis and tumor evolution. DESIGN: Laser capture microdissection (LCM) was carried out on archival formalin-fixed, paraffin-embedded sections from a tumor containing foci of classic papillary thyroid cancer and anaplastic thyroid cancer. DNA was extracted from each microdissected tumor focus. In addition, cryopreserved bulk normal and neoplastic thyroid tissue underwent DNA extraction. All DNA samples were subsequently evaluated for genomic instability by means of inter-simple sequence repeat polymerase chain reaction. RESULTS: The LCM DNA from each archival paraffin-embedded tumor focus demonstrated unique patterns of banding as compared with the cryopreserved tumor and normal tissue DNA. Thus, intratumoral variability in genomic instability was observed. Comparison of inter-simple sequence repeat polymerase chain reaction patterns of LCM DNA from adjacent foci of papillary and anaplastic tumors showed conserved genome alterations. CONCLUSIONS: At the genome level, thyroid tumors may be highly heterogeneous. The intratumoral histologic heterogeneity observed in thyroid neoplasms reflects genetically heterogeneous underlying tumor cell populations that are demonstrated by the observed differences in their rates and extents of genomic instability. The conserved genomic alterations in the microdissected papillary and anaplastic foci suggest intratumoral evolution, with transformation of a preexisting papillary tumor to anaplastic carcinoma.