Tricky case from Portugal: 53-y-o Danish male. Subcutaneous nodule on arm.
Asymptomatic. Rapid growth within a few months.
Immunohistochemistry: S100++, NKI/C3 very weakly expressed. All other markers
negative: HMB35, PGM3 [CD68], MelanA, AE1/3 (pan-cytokeratin), SMA [1A4], EMA.
Differential diagnosis: Parachordoma of the skin (likely? but not certain
because of cytokeratin negativity). Could this be a peculiar variant of Melanoma
??
Other suggestions?
Thanks for your kind help.
