Maculae ceruleae are caused by

Pediculosis Pubis (Pubic Lice) * Phthirus pubis, crab louse; wider shoer body than the body louse, resembling miniature crabs * Presents with itching of pubic area, may be erythema around hair follicles, excoriations, secondary bacterial infection, +- maculae caerulea: slate gray to blue macules. Ref:- Sima Jain; pg num:- 244