Pyoderma Gangrenosum: It’s not an infection…

Pyoderma Gangrenosum (PG) was initially described by Brunsting in 1930.  Classic PG begins as an inflammatory pustule with a surrounding halo that enlarges and subsequently ulcerates.  A primary lesion may not be seen and most of these patients present with frank ulcerations.  Satellite violaceous papules may be found peripheral to the border of the ulceration.  Often these lesions will break down and fuse with the ulcer.  PG typically occurs in adults age 40-60 years of age, most often involving the lower extremities and trunk.

Lesions usually heal with characteristic thin, atrophic, scars–also referred to as fish mouthed or cribiform scars.  PG lesions do not respond well to intervention.  The patient shown above experienced progressive expansion of the ulceration after surgical debridement.  Pathergy may be associated and help confirm a diagnosis.  There are other variants of PG, such as a pustular form that generally does not progress to frank ulceration, often associated with inflammatory bowel disease (IBD)Pyostomatitis vegetans and subcorneal pustular dermatosis are two other pustular neutrophilic disease reported to be associated with PG.  Major subtypes of PG are ulcerative, pustular, bullous and vegetative.

Overall over 50% of patients with PG have an associated disease, such as IBD (Crohn’s or Ulcerative Colitis), leukemia, myeloma, monoclonal gammopathy, polycythemia vera, myeloid metaplasia, chronic active hepatitis, hepatitis C, human immunodeficiency virus (HIV), systemic lupus erythematosus, pregnancy, PAPA syndrome and Takayasu arteritis.  It frequently is misdiagnosed as an infectious disease or a spider bite.  Factitial disease may also be very difficult to exclude clinically.

HISTOLOGY:  Early biopsies show a suppurative folliculitis and the affected follicle is often ruptured.  The the lesions evolve, they demonstrate suppurative inflammation in the dermis and subcutaneous fat.  Massive dermal edema and epidermal neutrophilic abscess are present at the violaceous, undermined border, which are not features that are diagnostic and are frequently associated with infectious diseases.

ETIOLOGY:  PG was initially believed to be caused by bacterial infections in an immunocompromised host.  It has been hypothesized that PG is a direct result of an aberrant immune response to “unidentified” factors.  Deposition of protein in blood vessels of the skin have been described as having and “arthus-like” reaction.

TREATMENT:  Local wound management is recommended, and extreme care must be taken in removing tissue.  This is directed at reducing inflammation; compresses or whirlpool baths followed by the use of ointments or hydrophilic occlusive dressings.  In smaller, localized lesions, topical steroids, intralesional steroids, tacrolimus and topical disodium chromoglycate under occlusion may be helpful.  However, the mainstay of treatment is systemic steroids with a slow taper.  Additional therapeutic modalities include cyclosporine, infliximab, etanercept, adalimumab, alefacept, ustekinumab, mycophenolate mofetil, granulocyte apheresis intravenous immune globulin (IVIG), alkylating agents, and thalidomide.  Adjunct treatments include sulfapyridine, sulfasalzine, salicylazosulfapyridine, dapson, methotrexate, azathiiprine, and mincycline.  To read more about PG click HERE, HERE and HERE.