女，42岁，右手第五掌骨紧贴骨膜见骨痂样组织，与周围软组织分界清，刮除后骨皮质光滑没有损伤。

内生软骨瘤。但最好看看X线片。

X线片已看过，位于骨旁，没有恶性肿瘤的特点。 

Microscopic
l 1.
The lesional tissue is composed of bone, cartilage, and fibrovascular connective tissue.
l 2.
The cartilage tends to be less well organized than is the case in osteochondromata.
l 3.
The endochondral ossification present in the lesional tissue tends to be less well organized than in osteochondromata.
l 4.
The spindle cell component of the lesion may show some mitotic activity, but no atypia is evident.
l 5.
A distinctive feature of BPOP is the presence of irregular calcified matrix, which stains blue (hematoxylin and eosin) and has been referred to as “blue bone.”
l 6.
The lesion is very well circumscribed at the periphery.

如果不在髓腔，诊断骨旁软骨瘤和楼上的“奇异性骨旁骨软骨瘤样增生”都可以。鉴别诊断主要靠X线，如钙化、边界与骨膜的关系等。

nora病