Sooty molds are saprophytic fungi living on plants and feeding on honeydew secreted by some parasitic insects. We present a case of a 41-year-old male laborer who developed hypo- and hyperpigmented areas on his hands, without signs of inflammation or allergic reaction, together with several episodes of bronchial asthma, after occupational handling of sooty mold-covered citrus fruit. While positive prick tests to Alternaria (+++) and Cladosporium (+++) demonstrated the allergic nature of the patient’s asthma, the pathogenic mechanism of skin dyspigmentation in such cases remains unknown. Hyperpigmentation could be due to intracutaneous penetration of a melanoid fungal pigment through repeated occupational microtraumatic events, while hypopigmentation could be caused by fungal products that are toxic/apoptosis-inducing for melanocytes and/or that interfere with melanogenesis (as observed for other fungi, such as Malassezia). This case suggests that further research is warranted in the probably underestimated field of sooty mold-related human diseases, and underlines the importance of education, use of protection devices, and prevention of sooty mold infestation in individuals exposed to these fungi.
