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Pyodermatitis-pyostomatitis vegetans

Author: Dr Delwyn Dyall-Smith FACD, Dermatologist, 2010.

Table of contents

What is pyodermatitis-pyostomatitis vegetans?

Pyodermatitis-pyostomatitis vegetans is a rare but characteristic pustular eruption of the mouth and skin folds consistently associated with inflammatory bowel diseases such as ulcerative colitis and less commonly Crohn disease.

The skin disease is pyodermatitis vegetans and the mucosal disease is pyostomatitis vegetans.

Who gets pyodermatitis-pyostomatitis vegetans?

Pyodermatitis-pyostomatitis vegetans is almost always seen in patients with ulcerative colitis or Crohn disease. The inflammatory bowel disease usually precedes the development of the skin and/or mouth problem by months or years. Sometimes however the bowel problem is only diagnosed when it is looked for after the skin/mouth diagnosis.

This condition usually develops in the age group 20-50 years although it has been rarely reported in children. It is more common in males than females (3:1).

What are the clinical features of pyodermatitis-pyostomatitis vegetans?

The characteristic lesion in pyodermatitis-pyostomatitis vegetans is the pustule.

On the skin, pyodermatitis vegetans presents as an asymmetrical rash most commonly in skin folds (a form of intertrigo), such as the armpits and groin, and the scalp. Less commonly the trunk, face and fingers/toes may be involved.

The typical features of pyodermatitis vegetans include:

  • redness
  • pustules
  • crusting
  • large raised (vegetating) plaques
  • Brown post-inflammatory pigmentation is prominent.

In the mouth, pyostomatitis vegetans consists of redness with multiple yellow or white pustules. The pustules (microabscesses) easily rupture, to form superficial ulcers (erosions) which have been likened to snail trails.

Signs in the lining of the mouth in pyostomatitis vegetans include:

  • swelling and thickening
  • cobblestoned appearance
  • raised growths (vegetations)

All sites within the mouth and throat can be affected, except the tongue and floor of the mouth are rarely involved. Vegetations tend to develop in areas of redness and occur most commonly on the gums and palate. On the inside of the lips and cheeks, swelling can cause the surface to become folded. Pain is variable and may be surprisingly mild. The lymph glands under the chin may be enlarged.

Other mucosal sites have been less commonly reported to be affected including the vulva, nose and eyelids.

The eruption can develop and progress very quickly, over days.

It is possible to have just the skin eruption or just the mouth eruption; both sites are not always affected. Usually the mouth lesions occur first, or at the same time as the skin is affected.

The bowel disease may be asymptomatic or cause such mild symptoms that it has not been previously diagnosed. In patients already known to have inflammatory bowel disease, the development of pyodermatitis-pyostomatitis vegetans may coincide with a flare in the bowel disease.

How is pyodermatitis-pyostomatitis vegetans diagnosed?

Skin and/or mucosal biopsies are required for routine histology and direct immunofluorescence (antibody test) to distinguish pyodermatitis-pyostomatitis vegetans from pemphigus vulgaris, Hallopeau type (pemphigus vegetans). On routine pathology, pustules (microabscesses) either within or just below the epidermis will be seen, typically with many eosinophils (early lesions) and/or neutrophils (late lesions). Granulomas do not occur. Direct immunofluoresence is negative or only weakly positive.

On blood tests, indirect immunofluorescence is negative, i.e., there are no skin antibodies circulating. The blood count almost always reveals an increased number of eosinophils. Liver abnormalities have been reported so these should also be tested for routinely.

Microbiological swabs for bacteria, viruses (herpes simplex), yeasts (candida) and fungi will show only normal flora. Swabs are important to perform to exclude infection especially when immunosuppressive therapy is planned.

The diagnosis of pyodermatitis-pyostomatitis vegetans is therefore made on the combination of:

  • clinical presentation
  • histological features
  • negative direct and indirect immunofluorescence
  • eosinophilia on blood test, and
  • exclusion of infection.

When a diagnosis of pyodermatitis-pyostomatitis vegetans is made, further investigation for associated inflammatory bowel disease should be performed in patients not already known to have this. This will usually involve at least a colonoscopy and bowel biopsy. Delayed diagnosis of typical inflammatory bowel disease up to two years after the mouth condition has been reported and therefore continued monitoring should be considered in those cases where endoscopy is initially reported to be normal.

What is the treatment of pyodermatitis-pyostomatitis vegetans?

Treatment is mainly aimed at controlling the bowel disease as then the skin and mouth lesions will also resolve.

In those rare cases where no bowel disease is found, topical treatment options may include:

Systemic treatments may include:

Nutritional supplements may also be required because the bowel disease may cause malabsorption. In one report, zinc supplements lead to improvement of the mouth lesions.

In severe cases, colectomy for the bowel disease has resulted in resolution of the mouth and skin lesions.



  • Bens G, Laharie D, Beylot-Barry M, Vergier B, Noblesse I, Beylot C, Amouretti M. Successful treatment with infliximab and methotrexate of pyostomatitis vegetans associated with Crohn's disease. Br J Dermatol 2003; 149: 181–4. Journal
  • Femiano F, Lanza A, Buonaiuto C, Perillo L, Dell’Ermo A, Cirillo N. Pyostomatitis vegetans: A review of the literature. Med Oral Patol Oral Cir Bucal 2009; 14: E114-7. PubMed
  • Hegarty AM, Barrett AW, Scully C. Pyostomatitis vegetans. Clin Exp Dermatol 2004; 29: 1-7. PubMed

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