Seven patients with blastomycosis-like pyoderma had skin lesions of four months' to six years' duration. The criteria for the diagnosis of blastomycosis-like pyoderma include the clinical presentation of large verrucous plaques with multiple pustules and elevated border, pseudoepitheliomatous hyperplasia with abscess histologically, and the growth of at least one pathogenic bacteria from the culture of a tissue-biopsy specimen. The differential diagnosis includes deep fungus infection (especially North American blastomycosis), bromoderma, pyoderma gangrenosum, mycobacterial infections, giant keratoacanthoma, and squamous cell carcinoma. Generally, the patients had one or more conditions that could have affected their systemic or local immunologic competence to infection. We believe that the clinical and histologic features in these cases of blastomycosis-like pyoderma were produced by an unusual, exaggerated, vegetating-tissue reaction to a primary or secondary bacterial infection.

Blastomycosis-like pyoderma: successful treatment with low-dose acitretin. Australas J Dermatol. 2005 May;46(2):97-100

Blastomycosis-like pyoderma typically presents as verrucous plaque(s) with a purulent discharge through multiple sinuses. Two patients with blastomycosis-like pyoderma developing on significantly sun-damaged skin are presented: an 84-year-old man with multiple painful nodules and plaques, and a 92-year-old woman with a solitary plaque on the left calf. Histopathology showed pseudoepitheliomatous hyperplasia with dermal foci of suppuration. Staphylococcus aureus was isolated from a biopsy specimen in the first patient, whereas the latter patient had Prevotella and Corynebacterium species. Investigations for fungi and mycobacteria yielded negative results. These microbiological findings further supported the clinicopathological diagnosis. Both patients failed to respond to oral doxycycline despite the in vitro susceptibility of the organisms. Treatment with low-dose oral acitretin was successful in both patients after 3-4 months.

Blastomycosis-like pyoderma in a case of chronic myeloid leukaemia.Postgrad Med J. 1992 May;68(799):363-5.

Blastomycosis-like pyoderma, a rare skin lesion which may clinically resemble true blastomycosis, is seen in immuno-compromised individuals. We report one such case in chronic myeloid leukaemia.

Hyperinflammatory proliferative (blastomycosis-like) pyodermas: review, mechanisms, and therapy.J Dermatol Surg Oncol. 1986 Mar;12(3):271-3.

Some sites of chronic localized infection have a vigorous granulocytic inflammatory response and develop marked tissue proliferation. This is most common in patients with poor nutrition, halogen ingestion or foreign bodies. The granulocytes release connective tissue-activating peptides which cause fibroblast proliferation and ground substance formation. The dermal papillae enlarge and support a larger germinative cell volume, producing pseudoepitheliomatous hyperplasia. Hypertrophic granulation tissue or "proud flesh" appears to be a similar phenomenon without the epithelial component. In a milder physiologic range this phenomenon probably accounts for the term "laudable pus."

Cutaneous infection and infestations

Cutaneous lesion associated with AIDS