Two years ago, the Dermatology Department of Wuhan First Hospital began receiving multiple patients with erythematous rashes resembling pityriasis versicolor. These patients presented with rashes in areas such as the axilla, waist, and buttocks, initially appearing as erythematous patches followed by desquamation. After partial healing, the rashes recurred. Upon medical examination, they were diagnosed with “granular parakeratosis.”
A team of experts conducted various examinations on the initial seven patients, and through detailed medical history inquiries, they discovered that all diagnosed patients had been in contact with disinfectant products containing benzalkonium chloride before the onset of the disease.
In April of last year, the expert team published a paper titled “Clinical Characteristics Analysis of 7 Cases of Granular Parakeratosis Induced by Benzalkonium Chloride Exposure” in the Chinese Journal of Dermatology. This achievement was recently awarded the hospital’s Excellent Medical Achievement Award.
Since 2022, the Dermatology Department of Wuhan First Hospital has continuously treated numerous patients with primary symptoms resembling pityriasis versicolor, with durations ranging from one month to one year. The main affected areas include the axilla, scapular region, waist, buttocks, groin, and around the breasts in females. The primary rash presentation involves erythematous patches followed by desquamation, with recurrent erythema and desquamation after partial healing. Some patients have been hospitalized repeatedly in multiple hospitals.
The director of the dermatology department, Chen Liuqing, and several experts formed a team to conduct skin tissue biopsies, PAS staining, and direct immunofluorescence examinations on the initial seven patients.
Literature search revealed several foreign papers linking the disease to contact with clothing disinfectants containing benzalkonium chloride. After thorough medical history inquiries, the expert team found that all diagnosed patients had been in contact with disinfectant products containing benzalkonium chloride before the onset of the disease. Subsequently, the experts advised patients to discontinue using disinfectants, avoid contact with disinfected clothing, and stop using all topical medications except moisturizers. After 4 to 6 weeks, the rashes of the patients subsided, and there were no recurrences during follow-up.
In April 2023, the expert team published “Clinical Characteristics Analysis of 7 Cases of Granular Parakeratosis Induced by Benzalkonium Chloride Exposure” in the Chinese Journal of Dermatology and released a popular science article titled “The Secret Behind Disinfectants – Starting from 7 Cases of Recurrent Erythematous Rashes Resembling Pityriasis Versicolor” on online platforms.
Chen Liuqing stated that when doctors encounter erythematous rashes and wrinkled leaf-like scales occurring in intertriginous areas clinically, they should consider the possibility of this skin disease. By further inquiring about the medical history to determine exposure to benzalkonium chloride, a correct diagnosis can be made. Rashes appear approximately 3-4 weeks after exposure to benzalkonium chloride, and they subside after 4 weeks of discontinuation, closely resembling the 28-day epidermal turnover cycle.
In the past year, the Dermatology Department of Wuhan First Hospital diagnosed nearly 50 cases of granular parakeratosis.
However, Chen Liuqing also pointed out that patients with granular parakeratosis induced by benzalkonium chloride accounted for only a small fraction of users of such disinfectants. Even within the same family, with members using the same washing machine for clothes, only one member showed symptoms, suggesting genetic susceptibility to such diseases.
Therefore, the appearance of a few cases of granular parakeratosis should not negate the value of benzalkonium chloride as a disinfectant. Benzalkonium chloride is widely used in skin disinfectants and detergents. In recent years, the frequency of disinfectant use by the public has increased significantly, possibly contributing to the higher incidence of granular parakeratosis.