Old but Gold: The Importance of Medical History in Diagnosing Neutrophilic Dermatoses Characterized by Pathergy. A Case of Pyoderma Gangrenosum

We describe the case of an 84-years old woman referred to our clinic without an established diagnosis in 2015 for the presence of multiple cervical ulcers since 2013, when she underwent vascular surgery of the carotid arteries. The ulcers had infiltrated and actively inflamed violaceous borders; they were itchy and showed signs of scratching. The patient had already been prescribed different antibiotic treatments, without any clinical improvement. Multiple biopsies had also been performed, but histology was not diagnostic, showing a non-specific dermal inflammatory infiltrate. Despite optimal wound care treatment, we observed a dramatic worsening of the skin lesions, spreading from the neck to the vertex, especially at sites of minor trauma (for example, starting from scratch lesions). The presence of pathergy, which consists in the occurrence of lesions at sites of trauma, suggested the diagnosis of pyoderma gangrenosum. Systemic glucocorticoid therapy was then prescribed, with quick improvement and nearly completes clinical remission. Our case confirms the importance of anamnesis and detailed collection of symptoms associated with the clinical manifestations in dermatological dermatoses such as pyoderma gangrenosum where imaging, histology and laboratory findings are often not very helpful for a correct diagnosis.