Association of Propionibacterium acnes with the efficacy of minocycline therapy for cutaneous sarcoidosis.

Background: Although tetracycline has been used to treat cutaneous sarcoidosis, the mechanism of action for this treatment remains unclear. This study evaluated the efficacy of minocycline treatment on cutaneous sarcoidosis and the relationship between its efficacy and the presence of Propionibacterium acnes in skin sarcoid lesions.
Methods: We retrospectively reviewed results in 13 patients with cutaneous sarcoidosis treated with minocycline at Saitama Medical Center between 2010 and 2017. To demonstrate the presence of P. acnes in the skin lesions, skin biopsy specimens from 11 of the 13 patients were evaluated with immunohistochemistry using a specific monoclonal antibody against P. acnes (PAB antibody).
Results: Of the 13 patients treated with minocycline, six patients (46%) achieved a complete response (CR) and seven (54%) had a partial response (PR). The skin lesions regressed in 1.5-5 months (average, 3.2 months) after treatment with minocycline. No relapse had occurred during the minocycline therapy. Elevated serum angiotensin-converting enzyme levels were observed in five of the patients, and the levels reduced after treatment with minocycline. P. acnes, identified as round bodies that reacted with PAB antibody, were observed in the skin sarcoid granulomas in all patients tested. The number of PAB-positive round bodies was significantly higher in the skin lesions of patients who had CR than in those who had PR.
Conclusions: These results suggest the effectiveness of minocycline for the treatment of cutaneous sarcoidosis and an association of P. acnes with the efficacy of minocycline therapy for cutaneous sarcoidosis.
(© 2020 the International Society of Dermatology.)