55 year old woman with a left posterior thigh mass. Histology shows a pleomorphic spindle cell tumor with numerous atypical mitotic figures (6/hpf) highlighted by phospho-histone-H3 (as illustrated here).
Phospho-histone-H3 (or PHH3) is a phosphorylated histone protein associated with mitoses. The unphosphorylated form is seen with apoptosis. Ref.
