Osteoid osteoma and osteoblastoma with clonal chromosome changes

Development and translational imaging of a TP53 porcine tumorigenesis model

Cancer is the second deadliest disease in the United States, necessitating improvements in tumor diagnosis and treatment. Current model systems of cancer are informative, but translating promising imaging approaches and therapies to clinical practice has been challenging. In particular, the lack of a large-animal model that accurately mimics human cancer has been a major barrier to the development of effective diagnostic tools along with surgical and therapeutic interventions. Here, we developed a genetically modified porcine model of cancer in which animals express a mutation in TP53 (which encodes p53) that is orthologous to one commonly found in humans (R175H in people, R167H in pigs). TP53(R167H/R167H) mutant pigs primarily developed lymphomas and osteogenic tumors, recapitulating the tumor types observed in mice and humans expressing orthologous TP53 mutant alleles. CT and MRI imaging data effectively detected developing tumors, which were validated by histopathological evaluation after necropsy. Molecular genetic analyses confirmed that these animals expressed the R167H mutant p53, and evaluation of tumors revealed characteristic chromosomal instability. Together, these results demonstrated that TP53(R167H/R167H) pigs represent a large-animal tumor model that replicates the human condition. Our data further suggest that this model will be uniquely suited for developing clinically relevant, noninvasive imaging approaches to facilitate earlier detection, diagnosis, and treatment of human cancers.

Osteoblastoma of the sacrum: report of 18 cases and analysis of the literature

STUDY DESIGN

Retrospective case series.

OBJECTIVE

(1) To analyze clinical and radiographical characteristics, treatment, and outcome in patients with sacral osteoblastoma, (2) to evaluate progression-free survival and local recurrence rate, and (3) to identify prognostic factors.

SUMMARY OF BACKGROUND DATA

Osteoblastoma is a rare tumor that has been reported to affect the sacrum from 7% to 17%. Symptoms are various and the diagnosis is often delayed.

METHODS

From 1980 to 2010, 18 patients with sacral osteoblastoma (16 males and 2 females) were treated at Rizzoli Institute. Lesion involved S1 (2 cases), S1-S2 (3 cases), S2 (1 case), S2-S3 (1 case), S2-S4 (1 case), S3 (2 cases), S3-S4 (5 cases), S4 (1 case), and almost the entire sacrum in 2 cases. According to Enneking classification for benign bone tumors, 13 (72%) were diagnosed at stage 2 and 5 (28%) at stage 3. Mean tumor volume was 64 cm (range, 2-441 cm). Nine patients had preoperative magnetic resonance imaging. Five patients had a previous inadequate intralesional surgery elsewhere. Treatment consisted in intralesional surgery (16 cases), intralesional surgery and radiotherapy (1 case), and wide resection (1 case). Local adjuvants used were phenol (7 patients), cryocoagulation with "iceball" technique (1 case). Embolizations were performed in 7 patients.

RESULTS

At a mean of 8.4 years (range, 1-28 yr), 15 patients (83%) remained continuously disease free, whereas 3 patients had local recurrence (17%). Progression-free survival was 87% at 5 years and 74% at 10 years. No statistical difference was found between patients who received or not local adjuvants (P = 1.254), older or younger than 20 years (P = 0.970), at stage 2 or 3 (P = 0.826), evaluated preoperatively with or without magnetic resonance imaging (P = 0.160), primarily treated versus patients with previous intralesional surgery elsewhere (P = 0.131).

CONCLUSION

In our series, curettage was successful in most of the patients. Local adjuvants did not seem to reduce the risk of local recurrence when combined with intralesional surgery.

LEVEL OF EVIDENCE

4.

Benign Bone-Forming Tumors: Approach to Diagnosis and Current Understanding of Pathogenesis

The diagnosis of benign bone-forming tumors continues to be based on the traditional approach to bone tumor diagnosis using knowledge of the spectrum of histopathologic features seen in these tumors in combination with clinical and radiological correlation. This review emphasizes the pathologic features and the clinical and radiological features that the surgical pathologist must have a working understanding of to make an accurate diagnosis and avoid confusion with other lesions, particularly osteosarcoma. New and persistent challenges facing the practicing pathologist and our current understanding of the cytogenetic and molecular abnormalities involved in the pathogenesis of these tumors are discussed.

Aggressive Osteoblastoma: A Case Report Involving a Unique Chromosomal Aberration

Osteoblastomas are rare bone-producing neoplasms that generally occur in the young and can be misdiagnosed as an osteosarcoma if correlation with clinical history, radiology, and histology is not carefully considered or if the several variants of osteoblastoma are not recognized. These variants lie on a morphologic spectrum between conventional osteoblastoma and osteosarcoma. Aggressive osteoblastoma is one such subtype. As the name implies, the histologic features of aggressive osteoblastoma may appear malignant, and its biologic behavior may separate it from conventional osteoblastoma. We report a case of aggressive osteoblastoma occurring in the femoral diaphysis of a 12-year-old girl; this osetoblastoma was dyssynchronous from the radiologic appearance and a diagnostic challenge. Cytogenetic evaluation of the neoplasm revealed a pseudodiploid clone with a balanced translocation involving chromosomes 4, 7, and 14. Using the premise that cytogenetics might be useful as a diagnostic tool for a more specific classification, we reviewed the literature in order to compare our findings with known chromosomal aberrations.

Histological study of osteoid osteoma's blood supply

The osteoid osteoma is a painful lesion with a special predilection for the femur and tibia of young patients. Although the lesion has been described as richly innervated, its vascular supply has not been critically appraised to date in the pathology literature. To this end, we have undertaken a morphological study of 16 archival cases of osteoid osteoma, focusing primarily on the patterns of vascularization, utilizing traditional histological and immunohistochemical approaches. The study demonstrated that a prominent arterial and arteriolar blood supply was a constant finding within the various zones of soft tissues, skeletal muscle, and bone surrounding the nidus. It also showed that the caliber of the vessels underwent gradual attenuation throughout their centripetal course toward the nidus, where the vessels lost their muscularis as they merged into the capillary network of the nidus. Immunostaining with antibodies to neurofilament and S100 proteins revealed a pattern of innervation that was overall less exuberant than that described in some reports and that was virtually absent from the nidus. Taken together with data reported in the radiological literature, our findings lead us to wonder whether the osteoid osteoma may represent a response to the local stimulation of bony tissue by a primarily aberrant vasculature, a hypothesis that warrants further elucidation using state-of-the-art imaging approaches.

Familial occurrence of osteoid osteoma

Familial occurrence of osteoid osteoma is an exceedingly rare event. This paper describes the second report of this event, where two siblings presented with this lesion in the same location, the proximal left femur. They both presented at 6 years of age, but 3 years apart.

Osteoid osteomas with chromosome alterations involving 22q

Cytogenetic analysis was performed in two osteoid osteomas. In both, the modal chromosome number was 46. One of the cases presented a del(22)(q13.1) as the sole clonal chromosome alteration. The other had clonal monosomies of chromosomes 3, 6, 9, 17, 19, and 21, as well as a +del(22)(q13.1) was detected as a non-clonal chromosome alteration. There is only one osteoid osteoma reported so far showing clonal karyotypic alterations. The cytogenetic behavior of osteoid osteomas described here was different from that of the osteoid osteoma of the literature. Numerical alterations of chromosomes 3, 6, 9, 17, 19, 21 and 22 have been described in several neoplasias including bone tumors. The breakpoint of chromosome 22 involves a region where important genes for the regulation of the cell cycle have been mapped.

Large cell, epithelioid, telangiectatic osteoblastoma: a unique pseudosarcomatous variant of osteoblastoma

A previously undescribed large-cell, epithelioid, and aneurysmal variant of osteoblastoma with minimal osteoid-production--simulating telangiectatic osteosarcoma, epithelioid angiosarcoma, and metastatic carcinoma is reported. The tumor occurred in the mandible of a 14-year-old girl. The light microscopic, immunohistochemical, ultrastructural, cell proliferation, and DNA-ploidy studies, as well as the 7-year disease-free follow-up period all indicate a benign osteoblastic tumor. Cytogenetically, the tumor had a pseudodiploid karyotype, distinguished by a complex t(1;5;17;22) and a terminal 1q deletion. Recognition of this unique, pseudomalignant variant of osteoblastoma is important to avoid an erroneous diagnosis of malignancy.