RESUMEN
The authors report on a clinical case of 91-year-old female patient presented with a two-year history of an enlarging forehead lesion with exudation and bleeding, suspicious of squamous cell carcinoma. Histology ruled out the suspected diagnosis, however the microbiology culture and polymerase chain reaction assay identified non-toxic Corynebacterium diphtheriae. Therefore the diagnosis of localized cutaneous diphtheria was confirmed. The patient was treated with penicillin regimen V 3 x 1 mio IU/ day for 10 days in complex with topical povidone-iodine. The chosen treatment achieved complete healing of the ulcer and no relapse has been reported during the 9-month follow-up. Cutaneous non-healing chronic ulcers can be caused by diphtheroid corynebacteria. Immediate diagnosis is important to exclude toxic variants, which need patient isolation and treatment of persons in close contact.