INTRODUCTION
Exogenous ochronosis (EO) is a common skin condition that presents as asymptomatic hyperpigmentation after using products containing hydroquinone. Other causative agents include resorcinol, phenol, mercury, picric acid, and antimalarials such as quinine. Hydroquinone in concentrations above 4% and treatment courses as short as 3 months may be associated with EO.1 We present the case of a patient with a classic history of hydroquinone use with contradicting biopsy findings.
CASE REPORT
A 79-year-old Black woman presented with a 10-year history of blue-black macules and patches on the face. She had no notable medical history. Cutaneous examination revealed multiple blue-black macules and patches distributed symmetrically over the periorbital, malar, and forehead regions (Figure 1). The lesions
A shave biopsy was performed and showed sparse superficial perivascular dermatitis with numerous melanophages, consistent with a diagnosis of lichen planus pigmentosus (LPP), confounding the final diagnosis. While the histopathologic findings did not show classic EO signs, the clinical diagnosis favors EO since the patient was using hydroquinone prior to
were arranged in a reticular, lace-like pattern. No other sites were involved, and systemic examination was normal.
Further history revealed the patient had been using topical skin-lightening creams for years prior to the onset of her skin findings (Figure 2). The skin lightening cream contained hydroquinone, which is often associated with exogenous ochronosis (EO). Discontinuing the skin-lightening creams halted the progression of the patient's skin lesions, supporting a diagnosis of EO.
A shave biopsy was performed and showed sparse superficial perivascular dermatitis with numerous melanophages, consistent with a diagnosis of lichen planus pigmentosus (LPP), confounding the final diagnosis. While the histopathologic findings did not show classic EO signs, the clinical diagnosis favors EO since the patient was using hydroquinone prior to
