Alireza Ghanadan - Department of pathology, Razi hospital and Cancer institute of Imam Khomeini hospital complex, Tehran university of medical sciences, Tehran, Iran
Amir Hooshang Ehsani - Department of dermatology, Razi hospital, Tehran university of medical sciences, Tehran, Iran
Sahar Dadkhah - Department of dermatology, Shohada Tajrish hospital, Tehran university of medical sciences, Tehran, Iran.
Somayeh Khezri - Department of dermatology, Razi hospital ,Tehran university of medical sciences, Tehran, Iran.

Introduction: Neutrophilic dermatosis (ND) is a heterogeneous group of diseases with various etiologies and clinical presentations. Different skin lesions like papule, vesiculopustule, plaques and nodule may be seen in patients, but all NDs share the common feature of neutrophil predominance in skin. Histological examination of patients with suspected ND is a key step for proper diagnosis.Methods: The aim of this article was to investigate histopathological aspects of the different NDs. We obtained our data from medical records of patients of Razi dermatology hospital, from 2012 to 2014. 38 biopsy records coded under the term of any ND, including SS, PG, skin lesions of Behcet s disease, neutrophilic drug eruption, amicrobial pustulosis of the folds, pustular vasculitis of the hands and undetermined ND were recruited in our study. The specimens were evaluated regarding inflammatory reaction pattern, epidermal/adnexal changes and dermal changes.Results: Most common ND in our study was pyoderma gangrenosum (42.1%) followed by Sweet syndrome (21.1%). Most common pattern of inflammatory reaction was superficial perivascular and interstitial dermal inflammation in 44.7% of the patients. Exocytosis of neutrophils into epidermis, hair follicle and eccrine gland was seen in 71%, 18.5% and 28.9% of specimens. Ulceration was only seen in 10 patients with PG. Dermal fibrosis and vascular proliferation were reported in all PG patients.Conclusion: Prevalence of some histopathological findings in different types of ND were significantly different. These features seemed to be helpful in distinguishing between different NDs.

neutrophilic dermatosis, pyoderma gangrenosum, Sweet s syndrome, Behcet s disease