Muco-cutaneous pigmentation and photosensitization induced by minocycline hydrochloride

A new type of minocycline-induced cutaneous hyperpigmentation

Pigmentary disorders are recognized adverse effects of the semi-synthetic tetracycline derivative antibiotic, minocycline. Three distinct types of minocycline-induced cutaneous pigmentation have been described. Type I, blue-black pigmentation confined to sites of scarring or inflammation on the face; Type II, blue-grey circumscribed pigmentation of normal skin of the lower legs and forearms; and Type III, diffuse muddy brown pigmentation of normal skin accentuated in sun-exposed areas. We report two patients with acne vulgaris with a fourth type of minocycline-induced cutaneous pigmentation. They presented with circumscribed blue-grey pigmentation within acne scars confined to the back. Histology showed pigment within dendritic cells, and extracellularly throughout the dermis. Histochemistry identified a calcium containing melanin-like substance. Iron was absent. Immunohistochemistry confirmed some pigment-containing cells to be macrophages. Electron microscopy demonstrated electron-dense granules, free and membrane-bound, within macrophages and fibroblast-like cells. Energy-dispersive X-ray analysis confirmed the presence of calcium. Iron was absent. This fourth type of cutaneous minocycline hyperpigmentation may be a variant of Type I, but based on clinical, pathological and microanalytical differences, appears to be a new entity. The pigment may be a drug metabolite-protein complex chelated with calcium, or an insoluble minocycline-melanin complex. We propose a classification of cutaneous minocycline pigmentation based on clinico-pathological criteria.

[Cyclines and acne: pay attention to adverse drug reactions! A recent literature review]

PURPOSE

Cyclines are broad-spectrum antibiotics often used in acne. Side effects might occur precociously or more insidiously during long term treatment such in acne. The aim of this study is to review all adverse effects recently reported in this indication.

CURRENT KNOWLEDGE AND KEY POINTS

A literature review from 1997 to 2001 has been conducted. Seventy-six articles reporting 250 cases have been found. Data analysis indicated that minocycline is the most widely incriminated molecule. Seventy-two cases revealed autoimmune disorders : lupus like syndrome associated or not with autoimmune hepatitis, 5 cases developed vasculitis. These reactions occurred in long term treatment (several weeks to several months). Fifteen cases of hypersensitivity syndromes and 3 cases of serum sickness like illness have been reported. These reactions occurred within the first weeks of exposure. Twenty-four cases of pseudotumor cerebri and 123 cases of abnormal pigmentations (skin, nails, mouth, bones or organs) have also been found. Eight cases presented other diseases.

FUTURE PROSPECTS AND PROJECTS

Adverse effects of cyclines might be serious and sometimes unknown. Long term treatment by tetracyclines must be researched in patients presenting such symptoms. Moreover, several adverse drug reactions might be avoided by an optimal use of the drug (oesophageal ulcerations, photosensitivity) or by shorter periods of treatment (autoimmune disorders, pigmentations); only DRESS are drug adverse reactions unpredictable and sometimes severe.