History
To evaluate a patient with possible sporotrichosis, investigate the history of risk factors for acquiring the fungus. Several predisposing factors may place a person at increased risk for developing sporotrichosis. Contact with certain plants known to harbor this fungus (eg, roses, sphagnum moss, salt-marsh hay, prairie hay) places patients at increased risk for the disease. The risk of this contact-acquired infection is increased among people in certain occupations, such as farmers or florists. Typical introduction of S schenckii into the skin has been described as occurring via a thorn or wood splinter. Transmission is also possible from infected cats or scratches from digging animals (ie, armadillos), with notable increased incidence in veterinarians. [10] Cats have been the animal found most common to transmit sporotrichosis. As said prior, they transmit most frequently through bites or scratches, however it is common for the exact transmission point from felines to humans to go unnoticed until infection occurs (Cutaneous Sporotrichosis). Infections have also been reported in medical technicians who were exposed to tissue or culture specimens of S schenckii.
Certain diseases, such as diabetes mellitus and alcoholism, also predispose a patient to develop localized disorders. In certain settings, patients who are immunocompromised are at risk for developing disseminated sporotrichosis.
Physical
Overall, this fungal infection most commonly affects the dorsum of the hands or fingers. Various primary lesions have been described, ranging from an erythematous papule or pustule to an ulcerating nodule.
Sporotrichosis can be divided clinically into 2 main categories: cutaneous and systemic.
-
Cutaneous sporotrichosis
The primary lesion is typically a pustule at the site of implantation. Erythematous papules, nodules, and verrucous plaques may also develop, along with secondary features such as ulceration and serosanguineous fluid drainage. Surprisingly, these lesions produce relatively few symptoms.
Lymphangitic cutaneous sporotrichosis is the most common form of the disease.
Lymphangitic cutaneous sporotrichosis is usually found on an exposed skin surface at the site of traumatic inoculation. A classic clinical setting would be an adult male who acquired a splinter that, despite removal, continued to produce an area of inflammation.
A pustule may slowly grow and may develop into a plaque or nodule. This nodule may eventually ulcerate. Examination proximally along the affected limb usually reveals small, deep-seated, satellite erythematous nodules along lymphatic drainage. If left untreated, the fungal infection continues to spread proximally, producing a significant amount of skin inflammation, abscesses, thickened lymphatic cords, lymphadenitis, and, eventually, systemic spread.
Spontaneous resolution may occur. Typically, early in the course of the disease, the patient's health is minimally affected, and the infection site bears minimal symptoms.
Cutaneous forms of sporotrichosis also include fixed cutaneous, cellulitic, and mycetomalike. Of these, fixed cutaneous sporotrichosis is the second main cutaneous form of the disease.
In its fixed cutaneous form, the fungus remains localized to the implantation site and no proximal lymphangitis or lymphadenopathy develops.
The fixed cutaneous form may tend to take on more of a verrucous plaquelike appearance. This form may represent enhanced host immune response to the fungus, possibly because of prior exposure. Skin surveys using the sporotrichin skin test have demonstrated that a positive test result occurs in up to 10% of certain populations, suggesting a history of prior exposure to S schenckii.
-
Systemic sporotrichosis
Less common systemic forms of sporotrichosis usually follow inhalation of the fungus. A pulmonary infection ensues, which serves as the primary dissemination route. Systemic sporotrichosis can be divided into a pulmonary form and a disseminated form, both causing higher morbidity and mortality than cutaneous sporotrichosis.
Pulmonary infection may remain localized to the lung or may disseminate to other body sites, including the skin, joints, bones, internal organs, and meninges. For instance, one case has been reported of laryngeal and respiratory tract sporotrichosis after steroid inhaler use.
This clinical situation has often been found in persons with alcoholism.
Erythema nodosum and vascular lesions resembling polyarteritis nodosum have also been reported in patients with sporotrichosis.
-
Clinical types of sporotrichosis
Localized cutaneous (chancriform) type: A subcutaneous papule or pustule develops at the site of inoculation after several weeks. Surrounding skin develops a pink-to-violaceous papulonodule, which may subsequently develop into a painless ulcer. The ulcer border is often ragged and undermined and draining a serosanguineous exudate. Draining lymph nodes may become tender and swollen.
Chronic lymphangitic (sporotrichoid) type: This is the most common and best recognized form of sporotrichosis; it may follow the chancriform type described above. Lymphangitic spread of the fungus produces nodular swellings in a linear array, spreading proximally up the affected extremity. Palpable lymphadenopathy is often an associated finding.
Fixed cutaneous sporotrichosis: Crusted verrucous plaques may occur in this type and are often found on the faces of children or the upper extremities of adults.
Disseminated sporotrichosis: The fungus spreads hematogenously to the skin, joints, eyes, and CNS. Multiple crusted and ulcerating papulonodules may occur. This form may have a widespread distribution (sparing the palms of the hands and the soles of the feet). [11, 12] The primary source of infection may be the lungs, or dissemination may occur from a cutaneous site in a patient who is immunocompromised.
Causes
See the list below:
-
Sporotrichosis is typically acquired by inoculation of the fungus into the skin during contact with certain plants or animals.
-
Classic scenarios include skin puncture by a splinter or rose thorn.
-
Bites or scratches from infected animals such as cats, dogs, and armadillos represent another source of infection.
-
Sporotrichosis with cutaneous necrosis and lymphangitic (sporotrichoid) spread. A 28-year-old white man presented for evaluation of a poorly healing, asymptomatic, round plaque acquired on the dorsum of his left hand. The lesion had been present for approximately 3 weeks.
-
Glucose-peptone agar culture plates revealing colony growth of Sporothrix schenckii. The left plate reveals older colonies as dark brown or black, and the right plate reveals younger white colonies with a brown center, characteristic of this fungus.
-
Microscopic examination of a blue dye preparation from the colony surface reveals elongated septate hyphae with groups of microconidia in a flowerlike arrangement.
-
A well-circumscribed, moderately elevated, erythematous plaque with central ulceration is found on the dorsum of this patient's left hand. Potassium chloride (KOH) stain was negative for fungal elements.
-
A 2 X 2 cm, dome-shaped, well-circumscribed, erythematous plaque is shown proximal to the left ring finger. The lesion was draining a serosanguineous fluid. No purulence was noted.
-
Biopsy rarely reveals the 6-mcg cigar-shaped yeast within tissue macrophages as shown in this histologic section. This is the morphology that Sporothrix schenckii assumes at 37°C.
-
Moist cream-colored colonies with a central, dark, leathery, and wrinkled surface growing at 25°C is highly suggestive of Sporothrix schenckii.
-
A fresh agar slant of Sporothrix schenckii reveals moist, white-to-cream–colored, yeastlike colonies.
-
Cutaneous, ulcerating, painless nodule on the hand and a classic sporotrichoid lymphangitic pattern spreading proximally up the arm.
