Genetic instability in primary leiomyosarcoma of bone

Primary leiomyosarcoma of bone--a clinicopathologic study of 8 uncommon cases with immunohistochemical analysis and clinical outcomes

Primary leiomyosarcoma of bone is a rare and a diagnostically challenging tumor entity. Over a 7-year period, we identified 8 such cases that fulfilled the diagnostic criteria in 6 men and 2 women, with age ranging from 25 to 59 years (mean, 42.7 years). All cases were noted in the lower limbs, including femur and tibia as the commonly involved bones in 4 and 3 cases, respectively. On radiography, the most consistent feature was a solitary osteolytic lesion with cortical destruction, unassociated with matrix formation. On histopathology, all cases showed spindly sarcomatous cells, mostly arranged in fascicles and whorls. Of 8 cases, 6 (75%) were of high grade. Prominent vasculature was noted in 5 cases. Two cases displayed focal mineralization, including calcification and heterotropic woven bone formation in 1 case each, but lacked malignant osteoid or chondroid matrix. One case showed osteoclast-like giant cells. On immunohistochemistry, smooth muscle actin was diffusely positive in all cases (100%), desmin was positive in 6 (75%) of 8 cases, and h-caldesmon was positive in 5 (83.3%) of 6 cases. Five cases underwent surgery, including 3 amputations and 2 wide excisions. One case underwent chemotherapy. On follow-up, 5 cases developed metastasis, including 1 case with another, who died within 17 and 5 months. Leiomyosarcoma of bone is uncommon and diagnostically challenging. An index of suspicion is necessary for this diagnosis, especially in cases of lytic, destructive bone lesions, unassociated with matrix production, that show spindly sarcomatous cells on histopathology. Immunohistochemical analysis, including an optimum panel formed by smooth muscle actin (diffuse positivity), desmin, and h-caldesmon, is necessary for substantiating this diagnosis. Surgery forms the treatment mainstay. The prognosis appears to be dismal.

Chromosomal and genetic imbalances in synovial sarcoma detected by conventional and microarray comparative genomic hybridization

PURPOSE

To analyze the relationship between chromosomal instabilities and clinicopathological factors in synovial sarcoma (SS).

METHODS

Twenty-two fresh-frozen SS were analyzed by metaphase comparative genomic hybridization (CGH). Additional microarray CGH was performed in 13 cases.

RESULTS

Fourteen patients with SYT-SSX1 rearrangements and nine patients with biphasic tumor subtypes had better prognosis than the eight patients with SYT-SSX2 rearrangements and 13 patients with monophasic subtypes, respectively. Gains (average 3.0) were more frequent than losses (average 1.0). Frequent gains were identified on chromosomal regions 2, 6q, 7, 8q, 12, 17q, 18q, and 21q, whereas frequent losses were over-lapped on chromosomes 1p31-p35, 3p, 6q, 16, and 17p. High-level gains were observed on chromosomes 1q21-q31, 7, 8, 12, 17q, 18q, and 21q. Thirteen monophasic and nine biphasic tumors had an average of 5.1 and 2.8 aberrations, respectively. Patients with tumors harboring numerous aberrations (>or=3) had a worse clinical course. Microarray CGH more specifically detected genetic imbalances including gains in MDM2, MSH2, KCNK12, DCC, CDK2, ERBB3, SAS, and CDK4 and losses in HRAS, RASSF1, and CCND1. Gain of SAS was an important prognostic factor of SS.

CONCLUSION

We have identified several factors influencing the prognosis of SS patients by metaphase and microarray CGH.