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
In 95% of cases, the organism is percutaneously inoculated
by contaminated thorns, tree bark, splinters, or animal bites.1 Rare
cases of human-to-human transmission have been reported. Sporotrichosis
has been reported in many areas of the United States but is most common
along the Mississippi River Valley and in the Plains states. Most
cases are sporadic, but outbreaks have been attributed to a single
source.2-4 Infection occurs in all age groups;
about 10% to 25% of cases occur in children.
The spectrum of clinical findings in sporotrichosis can be divided
into lymphocutaneous, fixed cutaneous, extracutaneous (localized
or multifocal), and pulmonary. Cutaneous infection is most common
in children; documented localized extracutaneous infections are
Lymphocutaneous sporotrichosis accounts for 75% of infections.
Following inoculation, the average incubation period is 3 weeks
but ranges from 5 days to 6 months. Lesions usually involve the
upper extremities but may occur on the face and trunk.5 The
primary lesion is a firm, mobile, nontender subcutaneous nodule
that enlarges and becomes discolored (Fig. 303-1).
After 2 weeks, it undergoes necrosis, leaving a painless ulcer.
During the next several weeks, additional lesions develop along
the proximal lymphatics; intervening lymphatic channels become thickened,
with overlying cutaneous erythema (Fig. 303-2). Lesions
can persist for months to years. Few heal spontaneously, with scarring
of the ulcers. Systemic symptoms are absent or mild.
Sporotrichosis: The ulcer and surrounding erythema of
fixed cutaneous sporotrichosis could be confused with a brown recluse
(Source: Knoop KJ, Stack LB, Storrow AB, Thurman RJ. The Atlas
of Emergency Medicine. 3rd ed. New York: McGraw-Hill; 2010.
Photo contributor: Edward J. Otten, MD.)
Sporotrichosis: Chronic lymphangitic type. An erythematous
papule at the site of inoculation on the index finger with a linear
arrangement of erythematous dermal and subcutaneous nodules extending
proximally in lymphatic vessels of the dorsum of the hand and arm.
(Source: Wolff K, Johnson RA: Fitzpatrick’s Color Atlas
and Synopsis of Clinical Dermatology. 6th ed. New York: McGraw-Hill;
Fixed cutaneous disease accounts for 20% to 25% of
cases and is common in children. Infection is limited to the site
of inoculation and consists of ulcerative, plaquelike, or maculopapular
lesions. They can resolve spontaneously, persist for years, or resolve
Extracutaneous disease accounts for less than 1% of
cases and may occur as localized or multifocal disease. Osteoarticular
manifestations are common and include destructive arthritis, tenosynovitis,
chronic osteomyelitis, and periostitis. Localized extracutaneous
infections may result from hematogenous dissemination, spread from
contiguous skin lesions, or from direct inoculation. The tibiae
and the bones of the hands are often affected. Arthritis is slowly
progressive, and symptoms include pain, swelling, and impaired function. Osteoarticular
disease usually remains localized but can spread to contiguous structures; dissemination
Multifocal extracutaneous disease results from hematogenous spread,
is rare in children, and occurs in immunocompromised patients.
In adults, predisposing conditions include AIDS, malignancy,
diabetes, sarcoidosis, alcoholism, and long-term corticosteroid
therapy. Sporotrichal meningitis is a rare but severe manifestation
of disseminated disease primarily seen in immunocompromised patients
and has a very poor prognosis. Primary pulmonary sporotrichosis,
seen mainly in adults, follows inhalation of spores. It may affect
the lung parenchyma or remain localized to the hilar nodes. There
is usually no extracutaneous site of infection. Apical portions
of the lung are involved, and chronic cavitary lesions may result.
Lesions can be progressive and fatal. Another pulmonary presentation involves
the hilar lymph nodes only and may mimic tuberculosis and histoplasmosis.
This manifestation can remain stable for long periods and often
Painless papulovesicular, ulcerative, or nodular lesions that
fail to respond antibiotics should prompt consideration of sporotrichosis.
The differential diagnosis includes infection with Nocardia species, Francisella
tularensis, nontuberculous mycobacteria, Treponema
pallidum, and Leishmania. Nodular lymphangitis can also
be seen with infections caused by pyogenic bacteria Pseudomonas species; Bacillus anthracis; and
other mycoses, including blastomycosis, chromoblastomycosis, coccidioidomycosis,
cryptococcosis, and histoplasmosis. Nodular lymphangitis can be
seen with mycetoma, which may be caused by bacteria or fungi. A
careful travel and exposure history helps differentiate these entities.
The laboratory diagnosis of sporotrichosis is problematic because
histopathologic findings of pyogranulomatous inflammation are not
diagnostic, few organisms are found in tissue, and their morphology
may not be typical. Using methodology appropriate for fungi, S
schenckii can be isolated from exudate or biopsied tissue, and
conversion of the mold to yeast forms is confirmatory.6 The
organism is more readily recovered from synovial fluid than from cutaneous
lesions. In cases of meningitis, the cerebrospinal fluid typically
shows a mild pleocytosis with a majority of lymphocytes, elevated
protein, and hypoglycorrhachia.
Serological testing has not proved useful for the diagnosis of
sporotrichosis and is not commercially available.7
Guidelines for the treatment of sporotrichosis have been published.8 Iodide
therapy is effective treatment of cutaneous disease and is often
utilized as a therapeutic agent in developing countries because
it is inexpensive and available. The mechanism by which iodide therapy
works is unknown. Five drops of a saturated solution of potassium
iodide mixed in water, milk, or juice is given 3 times daily; each
dose is increased by 5 drops weekly until a maximum of 40 to 50 drops
3 times daily for adults is reached. Maximum dosing in children
is 40 to 50 drops 3 times daily or 1 drop per kilogram of body weight, whichever
is lower. Treatment continues for 6 to 8 weeks after the resolution
of the lesions. Side effects include anorexia, nausea, a metallic
taste, rash, fever, and swelling of the salivary glands. The extended
length and inconvenience of treatment with iodide often leads to
poor compliance. Iodide therapy cannot be used in pregnancy.
Itraconazole is currently the recommended treatment for cutaneous
and localized lymphocutaneous sporotrichosis for adults and children (see Table 247-1). Response rates are excellent and
side effects are few. However, treatment is expensive. Care must
be taken to avoid drug interactions. The liquid preparation of itraconazole
is preferred. Serum concentrations should be documented to confirm
absorption (available through Miravista Diagnostics, Indianapolis, IN).
Lesions usually resolve within 1 month of beginning treatment; treatment
should be continued for several months after the lesions have healed
to decrease the likelihood of relapse. Itraconazole is also the
treatment of choice for isolated osteoarticular disease. Therapy
should continue for 1 to 2 years. Itraconazole may be used for treating
subacute or chronic pulmonary disease.
Fluconazole is considered effective but less active and can be
used if first-tier therapy is not tolerated.
Local hyperthermia has been effective for treating cutaneous
lesions because S Schenckii is growth impaired
at temperatures exceeding 42°C and may be considered for patients
who cannot tolerate the recommended drugs or during pregnancy. Local
hyperthermia may not be readily tolerated in children.
Amphotericin B is used to treat progressive disseminated and
pulmonary sporotrichosis or in initial treatment of osteoarticular
disease. In adults, most clinical experience has involved deoxycholate
amphotericin B; however, new treatment guidelines prefer lipid formulations of
amphotericin B because of fewer adverse effects. Amphotericin B
is preferred during pregnancy because the azoles should be avoided. Data
in children is lacking, but deoxycholate amphotericin B is recommended
for initial treatment of disseminated disease followed by itraconazole.
Treatment in AIDS patients is problematic because progressive infection
has been described in patients receiving amphotericin B, and the
relapse rate is high. Therefore, as with other systemic fungal infections in
AIDS patients, lifetime prophylaxis with itraconazole is recommended,
although discontinuation of treatment after 1 year if CD4 counts
recover may be considered. Amphotericin B is the preferred treatment
for infections of the central nervous system.