[Histonet] Artifact question

[path lab]

Hello fellow Histonetters,

I have posted the images referenced in this question as 'artifact image1',
'artifact image2', 'artifact image3', and 'artifact image4' to histonet.org.

This is believed to be an artifact resembling very early deposition of
mineral. The change is unusual for mineral deposits in its location and that
it appears to affect nuclei before cytoplasm. Early basophilia of
subepicardial individual cardiac myocytes is also seen (not shown). Note
that the von Kossa staining is more widespread than the H&E lesion would
appear to be. Does everyone agree that it is an artifact and does anyone
know how it happens?

Thanks in advance for your replies.