Chondromyxoid fibroma

Lobulated; spindle-stellate cells with zonation (peripherally increased cellularity)

Eosinophilic cytoplasm with long tapering processes

Ovoid nuclei with open chromatin, inconspicuous nucleoli, and mild atypia; inconspicuous mitotic activity 

Abundant pale basophilic chondromyxoid matrix with occasional ossification and osteoclast-type giant cells

Lobulated; spindle-stellate cells with zonation (peripherally increased cellularity)

Eosinophilic cytoplasm with long tapering processes

Hyperchromatic ovoid nuclei with occasional binucleation and mild atypia; inconspicuous mitotic activity 

Abundant pale basophilic chondromyxoid matrix 

Spindle-stellate cells with zonation (peripherally increased cellularity)

Eosinophilic cytoplasm with long tapering processes

Hyperchromatic ovoid nuclei with occasional binucleation and mild atypia; inconspicuous mitotic activity 

Abundant pale basophilic chondromyxoid matrix

IHC: smooth muscle actin, SATB2

Spindle-stellate cells with haphazard distribution 

Eosinophilic cytoplasm with long tapering processes

Hyperchromatic ovoid nuclei with occasional binucleation and mild atypia; inconspicuous mitotic activity 

Abundant pale basophilic chondromyxoid matrix; rare osteoclast-type giant cells; delicate thin-walled vasculature

IHC: smooth muscle actin

Lobulated; spindle-stellate cells with patternless distribution

Pale and eosinophilic cytoplasm with delicate tapering processes

Monomorphic ovoid nuclei with occasional binucleation; inconspicuous mitotic activity 

Abundant chondroid-myxoid stroma, along with scattered osteoclast-like multinucleate giant cells