RT Book, Section A1 Nobile, Donna M. A1 Kleiman, Martin B. A2 Rudolph, Colin D. A2 Rudolph, Abraham M. A2 Lister, George E. A2 First, Lewis R. A2 Gershon, Anne A. SR Print(0) ID 7029161 T1 Chapter 303. Sporotrichosis T2 Rudolph's Pediatrics, 22e YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-149723-7 LK accesspediatrics.mhmedical.com/content.aspx?aid=7029161 RD 2024/10/04 AB Sporotrichosis is an uncommon, chronic mycosis caused by Sporothrix schenckii. This ubiquitous plant saprophyte is a dimorphic fungus that grows as a mold at room temperature and as a yeastlike form in tissue. Although distributed worldwide, it is found most commonly in warm, highly humid regions and in temperate climates. Mexico, other parts of Central America, Asia, the United States, Canada, and France are endemic areas. Infection is characterized by isolated cutaneous or subcutaneous necrotizing nodules associated with the indolent development of suppurating nodules along the course of the proximal lymphatics. Extracutaneous and pulmonary forms of the disease occur infrequently. The histopathologic findings of primary cutaneous disease combine features of both granulomatous and pyogenic inflammation. Granulomatous lesions consist of aggregations of epithelioid histiocytes with central areas of necrosis and neutrophils or zones of Langhans giant cells associated with fibroblasts and lymphocytes. Occasionally, areas of microabscesses unassociated with granulomatous reaction may be seen. In chronic disease, pseudoepitheliomatous hyperplasia may be extensive and mimic neoplasm. A common histopathological feature is the asteroid body, a round basophilic, yeastlike structure surrounded by rays of eosinophilic material thought to represent antigen-antibody complexes. The asteroid body may also be seen in other mycoses.