Cellular cast containing macrophages. (hpf, unstained)

The yellow coloration is due to bilirubine. These casts are frequent in this condition.

Cellular cast containing macrophages. (hpf, Naphtyl chloro acetate esterase)

This Naphtyl chloro acetate esterase stain is relatively specific for granulocytes. Stain is also positive with some macrophages (due to the phagocytaded leucocytes )

Crystal needles are from the staining products.