PMC8607481_01
Radiological findings (a and b): X-rays showing sunburst focal perisostal
reaction. (c and d): MRI showing a cortico-medullary diaphyso-metaphysal
lesion (white star), with pericortical extension and soft tissue
invasion.
10.1177_2632010X211057555-fig1.jpg
PMC8607481_01_10.1177_2632010X211057555-fig1.jpg
fig1-2632010X211057555
Plain radiographs revealed a sunburst periosteal reaction (Figure 1). MRI was performed 2 weeks later, it demonstrated a locally advanced corticomedullary lesion in the distal femur with extension to soft tissue consistent with an osteosarcoma, which has rapidly increased in size (Figure 1).
Histological findings of the first biopsy: a lobular tumor, with peripheral
hypercellularity. Cells are mildly pleomorphic, spindled to stellate-shaped.
Nuclei are elongated, with diffuse chromatin, inconspicuous nucleoli, and
low mitotic activity. (a): HE x 40B: HE x 100, (b) HE x 400, and (c)
HE x 400.
10.1177_2632010X211057555-fig2.jpg
PMC8607481_01_10.1177_2632010X211057555-fig2.jpg
fig2-2632010X211057555
Nuclei were elongated, with diffuse chromatin, moderate hyperchromasia, inconspicuous nucleoli and low mitotic activity (1/10HPF (40x)) (Figure 2).
Histological findings of the second biopsy: a hypercellular lobular tumor
(a). Cells are mildly pleomorphic, spindled to stellate-shaped. Nuclei are
elongated, hyperchromatic, with diffuse chromatin (b), focal osteoid (c),
and mitotic figures (d). (a) HE x 40 Lobules show hypo and hypercellular
areas with peripheral condensation. (b) HE x 100 mildy pleomorphic cells
with nuclear atypia (white arrow). (c) HE x 400 focal osteoid (white arrow).
(d) HE x 400 mitotic figure (white arrow).
10.1177_2632010X211057555-fig3.jpg
PMC8607481_01_10.1177_2632010X211057555-fig3.jpg
fig3-2632010X211057555
Morphologically, the tumor showed similar features, but atypias were moderate to severe and mitotic count was estimated: 15 mitoses/10 HPF (Figure 3).