Here is a simple way to stain Macrophages:
I used it on bone samples.

Non-specific esterase (NSE) was determined by the azodye
coupling method.
The incubation medium consisted
of 5 mg of naphthol AS-MX acetate (Sigma) dissolved in
0.5 ml of dimethyl formamide and 40 mg of Fast Blue BB
salt (Sigma) in 25 ml of 0.1M sodium phosphate buffer (pH
7.1) containing 0.25 ml of propylene glycol. Sections were
incubated for 120 minutes at 25°C, rinsed in reaction
buffer, postfixed and mounted.

Image sections with regular light microscopy

Guy