摘要

Objectives: Paradoxical and iatrogenic dyschromias are both complications of long term use of skin lightening products. The clinical manifestations have not been meticulously defined and consensus on proper treatment has not yet been established. The objective of the presentation is to describe the clinical, histopathologic, and dermoscopy findings of exogenous ochronosis in 13 cases, and iatrogenic dyschromia in 8 cases. Treatment modalities and outcomes in all cases will also be shared. Introduction: Exogenous ochronosis is a paradoxical hyperpigmentation observed in patients who self-medicated with topical hydroquinone for the treatment of melasma. The condition is cosmetically disfiguring and treatment options are presently limited and unsuccessful. The term “iatrogenic dyschromia” has been used to describe the mottled pigmentation observed after long term and repeated exposure to pigment lasers. The clinical characteristics, dermoscopic findings and histopathology resemble the changes seen in poikiloderma of Civatte, however these characterics have not been thoroughly described. Materials / method: Case series of exogenous ochronosis (13 cases) and iatrogenic dyschromia (8 cases) seen at the Research Institute for Tropical Medicine and a private clinic from March 2007- .December 2022. Clinical manifestations, dermoscopy and histopathogical findings will be described. Different treatment modalities such as topical treatment, mesotherapy, lasers were applied on all patients. Results: For exogenous ochronosis, male to female ratio is 1:12. All 13 patients used over the counter hydroquinone 2% solutions without sun protection for a mean duration of 5.3 years. Clinically the patients presented with dark brown to black patches on the malar areas (100%). Eight patients presenting with with mottled pigmentation on the forehead, nose and cheeks resembled exogenous ochronosis clinically but histopathology was incompatible. These subset of patients were diagnosed with iatrogenic dyschromia and presents as mottled pigmentation on the face and responds poorly to melasma treatments. Conclusion: The patients were treated with the Q-switched Nd:YAG, 577 nm , and Er:YAG lasers with promising but variable results. Alternative hydroquinone and arbutin-free skin lightening agents and broad-spectrum sunscreens were prescribed for long-term use.