We report the unusual case of a 29-year-old female who developed black
discoloration of breast milk 3 weeks after commencing oral minocyclin
e therapy for acne vulgaris, Histochemical analysis of the breast milk
revealed the presence of pigment particles within macrophages with ir
on staining characteristics. We propose that the pigment may represent
an iron chelate of minocycline or one of its derivatives.