(6) Microscopically, it
is a highly cellular tumor composed of uniform round to
polygonal cells with well-defined cytoplasmic borders, round to ovoid
nuclei, predominantly growing in cellular sheets.
There are scattered
multinucleated osteoclastic giant cells arranged either singly or in
groups. Pericellular "chicken wire-like" calcifications are identified
pathognomonic of chondroblastoma.
"The 3 important
histopathological features of chondroblastoma are mononuclear cells (chondroblasts),
osteoclastic-like giant cells, and a chondromyxoid stroma surrounding
must be differentiated from other giant cell tumors. The osteoclastic-like
giant cells seen in chondroblastomas can have striking histological
similarities to giant cell reparative granulomas, aneurysmal bone
cysts, giant cell tumors, and chondromyxoid fibromas.
(8) Though normally
benign, histologically aggressive forms of the disease can also occur,
with associated high recurrence rates and occasional lung metastases.