Criteria for diagnosis histopathologically: A pustule housed in surface and infundibular epidermis–in the context of peri-folliculitis with remnants of a ruptured infundibulum, a dense nodular infiltrate of neutrophils, and abundant nuclear “dust” in the dermis and in the subcutis– is one presentation of cutaneous manifestations seen in patients with Crohn’s disease.
Differential diagnosis histopathologically: This process may be caused by infectious agents such as bacteria or fungi. Noninfectious causes include acne, topical agents that occlude ostia of infundibula, and systemic medications like corticosteroids or androgens. A pustular infundibulitis and perifolliculitis may also be found in the initial stage of pyoderma gangrenosum.
Criteria for diagnosis clinically: A red papule with a central pustule represents a suppurative peri-infundibulitis.
Differential diagnosis clinically: An infectious cause has to be ruled out by bacterial and fungal cultures.
Clinicopathologic correlation: The lesion is raised because of an infiltrate of inflammatory cells in the dermis. The central pustule corresponds to the collection of neutrophils in surface and infundibular epidermis. The erythema is due to dilation of small vessels in the dermis.
Options for therapy predicated on knowledge of histopathologic findings: Crohn’s disease is a chronic inflammatory bowel disease that requires systemic treatment with anti-inflammatory drugs such as corticosteroids, immunosuppressive agents like azathioprine or cyclosporine A, or alternatively anti-TNFalpha antibodies, such as infliximab or adalimumab.