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Background
This diverse group of fungal infections are caused by dematiaceous fungi. There are four main clinical presentations of the disease with overlap within some of the categories. The cutaneous lesions may present as solitary nodules, cysts, or verrucous proliferations. Infections often result from implantation of an infected splinter or other trauma. Immunocompromised patients are also at risk.
OUTLINE
HISTOLOGICAL TYPES CHARACTERIZATION GENERAL Under the microscope, there is a circumscribed cyst or abscess in the lower dermis or subcutis. It is walled off with dense fibrous tissue infiltrated by chronic inflammatory cells with scattered giant cells. The central cyst contains necrotic debris with neutrophils. The fungi are brown and filamentous.
An unusual dematiaceous fungal infection of the skin caused by Fonsecaea pedrosoi: a case report and review of the literature.Hamza SH, Mercado PJ, Skelton HG, Smith KJ.
University of Alabama at Birmingham, Pathology, and University of Alabama at Birmingham, Dermatology, Birmingham, AL, USA.
J Cutan Pathol. 2003 May;30(5):340-3. Abstract quote BACKGROUND: A case of an unusual dematiaceous fungal infection of the skin in a 43-year-old man with diabetes mellitus treated with steroids for reactive airway disease is presented. He developed chromoblastomycosis in the left wrist and was treated with antifungals and multiple surgical excisions.
RESULTS: Histologic examination of the excised tissue revealed widespread suppurative granulomatous inflammation in the dermis and subcutaneous tissue. Thick-walled internally septated brown fungal cells were found both inside multinucleated giant cells and extracellularly. Non-to-lightly pigmented septate hyphal elements, however, were also identified with special stains and, in retrospect, on one of the routinely stained sections. In culture, the organism was reported to initially grow as soft white colonies that soon turned to black and velvety.
CONCLUSIONS: The two unusual features of this case include the controversial report of the organism's initial growth in culture as soft white colonies and the presence of hyphal elements in addition to the sclerotic bodies in the dermis and subcutaneous tissue. This has not been reported before in human cases of dermal infection by Fonsecaea pedrosoi.Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
Dematiaceous fungi-Group of pigmented fungi, worldwide distribution, predominately in tropical and subtropical areas. Present in soil and decaying vegetable matter. The pigment is caused by melanin pigment. They cause two groups of infections-chromomycosis and phaeohyphomycosis.
Sclerotic bodies (Muriform cells)-An intermediate vegetative form of the fungus, arrested between yeast and hyphal morphology. These are round, thickwalled, golden brown cells, about 5-12 um in diamater, present in giant cells and occasionally in intraepidermal microabscesses.
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Last Updated January 16, 2007
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