Sporotrichosis is a fungal skin infection caused by Sporothrix schenckii, an organism primarily found on plants and flowers and in soil. The problem is common among gardeners and florists. It also affects those who handle animals, since the fungus may inhabit claws. Infection occurs when contaminated thorns, spines, or claws penetrate the victim’s skin. After an average incubation period of 3 weeks, localized infections become apparent. “Fixed” cutaneous infections are localized to the inoculation site and are manifest as 2- to 4-mm papules or nodules. They may ulcerate or become surrounded by raised erythema. They are typically painless. Progression to lymphocutaneous infections occurs in about 70% of cases. Patients present with a nodule at the site of penetration, with appearance of subcutaneous nodules and skip areas along lymphatic tracks later. The lesions may wax and wane over months to years. Patients with cutaneous sporotrichosis typically lack systemic symptoms.
Fixed Sporotrichosis. The ulcer and surrounding erythema of fixed cutaneous sporotrichosis could be confused with a brown recluse spider bite. (Photo contributor: Edward J. Otten, MD.)
Management and Disposition
Sporotrichosis may be successfully treated with oral potassium iodide for 1 month after clinical manifestations have resolved. Alternative therapy includes oral itraconazole, ketoconazole, or terbinafine, whereas disseminated infections may require intravenous amphotericin B. Outpatient therapy is appropriate for nondisseminated infections. Tetanus status should be addressed.
Fungal cultures and tissue biopsy cultures can be useful to confirm the diagnosis.
Treatment should be continued for 1 month following clinical resolution to eradicate S schenckii.
Although rare, a pulmonary form of sporotrichosis after inhalation exposure has been reported.
Lymphocutaneous Sporotrichosis. Lymphatic spread is common in cutaneous sporotrichosis. (Photo contributor: Kevin J. Knoop, MD, MS.)