Pseudomycetoma caused by Microsporum canis in an immunosuppressed patient: a case report and review of the literature.
BACKGROUND
A 65-year-old woman with a history of liver and kidney transplantation presented with a pruritic and tender rash of 2-year duration on her left knee.


METHODS
The patient had a physical examination, and multiple skin biopsies were performed.


RESULTS
Examination showed a cluster of dome-shaped, violaceous papules. A skin biopsy specimen showed multiple granules containing basophilic material within the superficial to mid dermis. The grains were embedded in an eosinophilic substance and surrounded by granulomatous inflammation. A Gomori methenamine silver stain showed abundant septate hyphae, and cultures grew colonies of Microsporum canis. A diagnosis of dermatophytic granuloma, or pseudomycetoma, was made. After considering the patient's immune status, a prolonged course of fluconazole was initiated.


CONCLUSIONS
Microsporum canis, a frequently encountered zoophilic dermatophyte associated with tinea capitis and tinea corporis, is rarely associated with a mycetoma-like presentation, grain formation, or systemic infection. The medical literature describes only six cases of M. canis causing mycetoma-like formations in immunocompromised and immunocompetent patients. This case report describes an unusual presentation of a common dermatophyte infection, and the literature review summarizes the importance of recognizing atypical presentations of dermatophyte infections. Such infections may warrant more aggressive treatment in immunocompromised patients.
Berg
Jena C
JC
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA.
Hamacher
Kirsten L
KL
Roberts
Glenn D
GD
D000368:Aged; D000935:Antifungal Agents / Q000627:therapeutic use; D003881:Dermatomycoses / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D005260:Female; D015725:Fluconazole / Q000627:therapeutic use; D006099:Granuloma / Q000276:immunology / Q000473:pathology; D006801:Humans; D016867:Immunocompromised Host; D007166:Immunosuppressive Agents / Q000009:adverse effects; D016030:Kidney Transplantation / Q000276:immunology; D016031:Liver Transplantation / Q000276:immunology; D008864:Microsporum
D000935:Antifungal Agents; D007166:Immunosuppressive Agents; D015725:Fluconazole