Pyoderma gangrenosum (PG) is a rare disease. She is often under diagnosed and a source of diagnostic wandering and inadequate care. Moreover, its association in more than one case out of two to a significant underlying pathology, such as inflammatory bowel disease, inflammatory rheumatism, or hematology, makes its diagnosis essential. Its pathophysiological mechanisms remain controversial and many other comorbidities have been reported in the literature, including endocrinological, cardiovascular and metabolic, neoplastic and autoimmune comorbidities.

The objective is to study the field, comorbidities and pathologies associated with PG on a series of patients diagnosed with PG, as well as to characterize the clinical and histological aspects of lesions.

A retrospective observational non-interventional multicenter study is proposed. 10 French centers. The recruitment will be done via the DIM using coding software: codes L984 , L982 and L97 according to 2 major criteria (typical clinical appearance with ulceration well limited and purulent or pustule hutches, exclusion of differential diagnoses) and at least 2 minor criteria (among compatible histological aspect, classically compatible associated pathologies, corticosensitivity of lesions, pathergie phenomenon, painful lesions).

Demographic data, clinical appearance of the lesions, cardiovascular and metabolic comorbidities, other associated pathologies, histological findings of the ulcer biopsy and biological results to describe the population and associated pathologies or comorbidities to PG

Pyoderma gangrenosum (PG) is a rare disease. She is often under diagnosed and a source of diagnostic wandering and inadequate care. Moreover, its association in more than one case out of two to a significant underlying pathology, such as inflammatory bowel disease, inflammatory rheumatism, or hematology, makes its diagnosis essential. Its pathophysiological mechanisms remain controversial and many other comorbidities have been reported in the literature, including endocrinological, cardiovascular and metabolic, neoplastic and autoimmune comorbidities.

The objective is to study the field, comorbidities and pathologies associated with PG on a series of patients diagnosed with PG, as well as to characterize the clinical and histological aspects of lesions.

A retrospective observational non-interventional multicenter study is proposed. 10 French centers. The recruitment will be done via the DIM using coding software: codes L984 (chronic skin ulceration), L982 (febrile neutrophilic dermatosis) and L97 (leg ulcer) according to 2 major criteria (typical clinical appearance with ulceration well limited and purulent or pustule hutches, exclusion of differential diagnoses) and at least 2 minor criteria (among compatible histological aspect, classically compatible associated pathologies, corticosensitivity of lesions, pathergie phenomenon, painful lesions).

Demographic data, clinical appearance of the lesions, cardiovascular and metabolic comorbidities, other associated pathologies, histological findings of the ulcer biopsy and biological results to describe the population and associated pathologies or comorbidities to PG

Inclusion Criteria:

• 2 major criteria (typical clinical appearance with well-defined ulceration and purulent or pustule hutches, exclusion of differential diagnoses)
• at least 2 minor criteria (among compatible histological aspect, classically compatible associated pathologies, corticosensitivity of the lesions, pathergie phenomenon, painful lesions).

Exclusion Criteria:

• patients with less than 2 major criteria
• patients with less than 2 minor criteria

All patients with pyoderma gangrenosum