Sporotrichosis

Lymphocutaneous infections are most common. They characteristically involve one hand and arm, although they can occur anywhere on the body; primary lesions may occur on exposed surfaces of the feet or face.

A primary lesion may appear as a small, nontender papule or, occasionally, as a slowly expanding subcutaneous nodule that eventually becomes necrotic and sometimes ulcerates. Typically, a few days or weeks later, a chain of lymph nodes that drain the affected area begins to enlarge slowly but progressively, forming movable subcutaneous nodules. Without treatment, overlying skin reddens and may later necrose, sometimes causing an abscess, ulceration, and bacterial superinfection. Systemic symptoms and signs of infection are notably absent.

Lymphocutaneous sporotrichosis is chronic and indolent; it is potentially fatal only if bacterial superinfections cause sepsis.

Rarely, in patients without primary lymphocutaneous lesions, hematogenous spread leads to indolent infections of multiple peripheral joints, sometimes bones, and, less often, genitals, liver, spleen, kidneys, or meninges. These infections are more common among patients with immunocompromise due to another disorder (eg, alcohol use disorder). Equally rare is chronic pneumonia caused by inhaling spores and manifested by localized infiltrates or cavities, most often in patients with preexisting chronic lung disease.

The diagnosis of sporotrichosis is suspected based on clinical presentation in a patient with a history of possible exposure to the fungus (eg, gardener, landscaper, forester).

The characteristic nodular lymphangitis/cutaneous clinical presentation of sporotrichosis can also be caused by other pathogens, including Mycobacterium tuberculosis Tuberculosis (TB) Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include... read more , atypical mycobacteria, Nocardia Nocardiosis Nocardiosis is an acute or chronic, often disseminated, suppurative or granulomatous infection caused by various aerobic soil saprophytes of the gram-positive bacilli genus Nocardia.... read more , Francisella tularensis Tularemia Tularemia is a febrile disease caused by the gram-negative bacterium Francisella tularensis; it may resemble typhoid fever. Symptoms are a primary local ulcerative lesion, regional lymphadenopathy... read more , and Leishmania brasiliensis Leishmaniasis Leishmaniasis is caused by species of Leishmania. Manifestations include cutaneous, mucosal, and visceral syndromes. Cutaneous leishmaniasis causes painless chronic skin lesions ranging... read more . Microbiologic diagnosis can usually be made when appropriate histologic stains and cultures of biopsied tissues are obtained (1 Diagnosis reference Sporotrichosis is a cutaneous infection caused by the saprophytic mold Sporothrix schenckii. Pulmonary and hematogenous involvement is uncommon. Symptoms are cutaneous nodules that spread... read more ). During the early, nondisseminated stage, the primary lesion is sometimes misdiagnosed as a spider bite.

Culture of tissue from the active infection site provides the definitive diagnosis. S. schenckii yeasts can be seen only rarely in fixed-tissue specimens, even with special staining. Serologic tests are not available.

Oral itraconazole 200 mg orally once a day given until 2 to 4 weeks after all lesions have resolved (typically 3 to 6 months) is the treatment of choice.

Severe infection requires a lipid formulation of amphotericin B (3 to 5 mg/kg IV once a day); after a favorable response, treatment is switched to oral itraconazole for a total of 12 months of treatment. AIDS patients may require lifelong maintenance therapy with itraconazole for meningeal and disseminated infection. Posaconazole may have a role.

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