Atypical case of ecthyma gangrenosum mimicking a breast cancer recurrence.

A 68-year-old woman with a history of breast cancer presented with skin lesions and sternal pain. Clinical examination revealed ulcerative lesions on mastectomy scar and CT scan showed contiguous sternal osteolysis. The main hypothesis was a breast cancer recurrence; however, cutaneous and bone biopsies did not reveal any cancer cells. Skin tissue culture detected Pseudomonas aeruginosa, suggesting ecthyma gangrenosum despite the absence of bacteraemia in our patient and despite her immunocompetence. Surgical treatment was performed, followed by a long course of antibiotherapy.