Advertisement
Mayo Clinic Proceedings Home

The Blastomycosis Bluff by Purpureocillium lilacinum

      A 73-year-old patient with a history of rheumatoid arthritis and inclusion body myositis on long-term prednisone and azathioprine presented with a 3-month history of tender erythematous nodules on his right lower extremity (Figure 1). A skin biopsy revealed yeast forms with broad-based budding yeast (Figure 2, [arrow]). Initially, a diagnosis of cutaneous blastomycosis was made, and he was initiated on itraconazole. However, (1-3)-β-d-glucan assay was elevated at >500 pg/mL (reference range: <80 pg/mL), and biopsy culture was returned 11 days later growing a violet-colored colony (Figure 3) identified as Purpureocillium lilacinum under microscopy, with phialides with swollen bases and pigmented and rough-walled conidiophore stipes (Figure 4). Review of previous biopsy identified hyphal elements in addition to yeast forms, and he was switched to voriconazole. At 2-month follow-up, he had significant reduction in pain, erythema, and there was healing of open ulcerations.
      Figure thumbnail gr1
      Figure 1Lesions present on the medial right lower extremity (91 x 68 mm [300 x 300 DPI]).
      Figure thumbnail gr2
      Figure 2Skin biopsy with broad-based budding yeast (arrow) under 400× magnification with Gomori methenamine silver stain.
      Figure thumbnail gr3
      Figure 3Fungal colony with a purple hue on Sabouraud dextrose agar.
      Figure thumbnail gr4
      Figure 4Photomicrograph of Scotch tape preparation of fungal culture with lactophenol aniline with polyvinal alcohol stain under 400 x magnification.
      Purpureocillium lilacinum is a ubiquitous fungus that can infect immunocompromised patients.
      • Pastor F.J.
      • Guarro J.
      Clinical manifestations, treatment and outcome of Paecilomyces lilacinus infections.
      Owing to its ability to sporulate in tissues, it can be confused with Blastomyces dermatitidis but is differentiated by the presence of hyphal elements within tissue biopsy, elevated (1-3)-β-d-glucan, and growth on cultures. Purpureocillium lilacinum is also resistant to amphotericin B, fluconazole, and itraconazole: agents often used to treat blastomycosis, highlighting the importance of definitive diagnosis.
      • Sotello D.
      • Cappel M.
      • Huff T.
      • Meza D.
      • Alvarez S.
      • Libertin C.R.
      Cutaneous fungal infection in an immunocompromised host.
      This case illustrates the importance of incorporating all available clinical, laboratory, pathological, and microbiological data when approaching infections in immunocompromised hosts.

      References

        • Pastor F.J.
        • Guarro J.
        Clinical manifestations, treatment and outcome of Paecilomyces lilacinus infections.
        Clin Microbiol Infect. 2006; 12: 948-960
        • Sotello D.
        • Cappel M.
        • Huff T.
        • Meza D.
        • Alvarez S.
        • Libertin C.R.
        Cutaneous fungal infection in an immunocompromised host.
        JMM Case Rep. 2017; 4: e005101