Low power: Pap Stain
Predominantly cohesive clusters in hypercellular smear; scattered single cells in the background. Cohesion prominent around vessels.
High power: Pap Stain
Cohesive clusters with monomorphic, histiocytoid spindle cells
Multinucleated giant cells adherent to the periphery of mononucleated cell clusters.
High power: DQ stain
Cohesive clusters of mononucleated cells with foamy cytoplasm .
High power: Pap stain
Lack of nuclear pleomorphism, rare nuclei with grooves and nuclear pseudoinclusions .
Cell block: H&E stain
Cohesive sheet of mononucleated spindle cells with scattered, numerous and evenly spaced giant cells .
Cell block: CD68 stain
Immunoreactivity of both mononucleated and multinucleated cells, consistent with their putative histiocytic/monocytic lineage.
Cell block: p63 stain
Immunoreactivity of mononucleated cells, nuclear pattern.
Cell block: MITF stain
Immunoreactivity of both multinucleated cells and mononucleated cells.
Features
• High cellularity
• Predominantly cohesive fragments
• Cell clustering around vessels
• Dual cell population
• Mononucleated, histiocytoid, spindle cells
• Foamy cytoplasm
• Multinucleated giant cells attached to mononuclear cell cluster
• Ovoid nuclei; same nuclei in mononucleated and multinucleated cells
• Lack of significant pleomorphism
• Lack of nucleoli
• Rare nuclear grooves and pseudo-inclusions
• Absent to very rare mitoses
• Absent to very rare apoptosis
• Absent to very rare necrosis
• Absent to very rare hemosiderin laden macrophages (as opposed to Giant cell tumor of tendon)
Gupta K et al. Diagn Cytopathol. 2004 Jan;30(1):14-8.