Skin pigmentation secondary to minocycline therapy
J. D. McGrae Jr and A. S. Zelickson
Localized brown to blue-black discoloration of the skin occurred in three
patients receiving long-term minocycline hydrochloride therapy. Abundant
perivascular pigmented material was present at all levels of the dermis
below the upper papillary portion. Histochemical studies demonstrated
reactivity with the Prussian blue stain and the Fontana-Masson silver
technique. The granules were brightly refractile by dark-field
illumination. Ultrastructurally, there were membrane-bound dense
intracellular inclusions differing from melanin and iron but identical to
those known to occur in the thyroid glands of minocycline-primed laboratory
animals. The abnormal pigment most likely represents a metabolic derivative
of minocycline.
