XXXX of bone--a clinicopathologic study of 8 uncommon cases with immunohistochemical analysis and clinical outcomes.

@entity1 @entity2283 @entity5 @entity79 @entity1822 @entity690 @entity3
@entity1822 of bone is a rare and a diagnostically challenging @entity5 entity. Over a 7-year period, we identified 8 such cases that fulfilled the diagnostic criteria in 6 @entity1 and 2 @entity1 , 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 @entity690 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%), @entity2283 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 @entity3 , including 1 case with another, who died within 17 and 5 months. @entity79 is uncommon and diagnostically challenging. An index of suspicion is necessary for this diagnosis, especially in cases of lytic, destructive @entity79 , unassociated with matrix production, that show spindly sarcomatous cells on histopathology. Immunohistochemical analysis, including an optimum panel formed by smooth muscle actin (diffuse positivity), @entity2283 , and h-caldesmon, is necessary for substantiating this diagnosis. Surgery forms the treatment mainstay. The prognosis appears to be dismal.
