Fig 1a: Dorsomedial view of the mass at first clinical
inspection. Fig 1b: Dorsopalmar radiograph of the third metacarpal bone.
There is excessive bone production with trabeculae and bone lysis
centered on the proximomedial aspect of the left third metacarpal bone.
Fig 1c: Dorsomedial - palmarolateral oblique radiograph showing
periostal reaction at the diaphyseal aspect of the second and third
metacarpal bone. Centrally there is a radiolucent zone (lysis) at the
palmaromedial edge of the third metacarpal bone and at the dorsal edge
of the second metacarpal bone.
Fig 2: Histological slides with hematoxylin (A) and eosin
(B) staining of the mass. Multiple partially mineralized bone trabeculae
(black arrow) are present. In between the trabeculae, there is a dense
proliferation of fibroblasts forming bundles and vortices. The
fibroblasts have an oval nucleus with fine-grained chromatin and an
indistinctly delineated, fibrous eosinophilic cytoplasm. Occasionally,
there are osteoclasts (asterisk) and some large dilated veins.
Morphologically the mass is diagnosed as a peripheral fibroblastic
osteosarcoma .