Sporotrichosis overview

# Overview
Sporotrichosis (also known as "rose gardener's disease") is a disease caused by an infection of the fungus Sporothrix schenckii.  This fungal disease usually affects the skin, although other less common forms can affect the lungs, joints, bones, and even the brain.  Because roses can spread the disease, it is one of a few diseases referred to as rose-thorn or rose-gardeners' disease.
Because S. schenckii is naturally found in soil, hay, sphagnum moss, and plants, it usually impacts farmers, gardeners, and agricultural workers. Typically, infection manifests following the interruption of the epidermal integrity, as this allows the fungus to enter the host.  In cases where sporotrichosis impacts the lungs, known as pulmonary sporotrichosis, the fungal spores enter through the respiratory pathways upon inhalation. Zoonotic transmission of sporotrichosis occurs most frequently from handling infected cats, making this an occupational hazard for veterinarians.
Sporotrichosis progresses slowly - the first symptoms may appear 1 to 12 weeks (average 3 weeks) following initial exposure to S. schenckii, and the patient may not recall the injury that led to infection. Serious complications can also arise in patients with compromised immune systems. As systemic forms of sporotrichosis, also known as extracutaneous sporotrichosis, are opportunistic infections, immunocompromised patients are much more susceptible to these more severe subtypes.

# Historical Perspective
The first definitive case of sporotrichosis was described by Benjamin Schenck, an American medical student, in 1896.

# Classification
Sporotrichosis may be classified, according to the location of the lesions, into particular subtypes: fixed cutaneous, lymphocutaneous, disseminated cutaneous, and extracutaneous/systemic. These subtypes may be further separated into increasingly specific forms based upon clinical manifestations.

# Pathophysiology
S. schenckii is usually transmitted via posttraumatic inoculation to the human host, however, infrequently sporotrichosis may also develop as a result of spore inhalation. The pathophysiology of sporotrichosis depends on the histological subtype and the frequently nonspecific histopathology may mimic other granulomatous diseases. S. schenckii is capable of modulating the immune response to promote its own survival by blocking cytokine production by macrophages.

# Causes
Sporothrix schenckii is a fungus that can be found throughout the world. Areas characterized by warm, humid climates, are ideal for the fungus to thrive. The species is present in soil as well as in and on living and decomposing plant material such as peat moss. It can infect humans as well as animals and is the causative agent of sporotrichosis, commonly known as "rose handler's disease".

# Differential Diagnosis
As sporotrichosis manifests in a variety of clinical forms, differentiation must be established in accordance with the particular subtype. Forms of cutaneous sporotrichosis must be differentiated from other diseases that cause lesions, such as cutaneous leishmaniasis and mycobacteriosis, while the various forms of extracutaneous sporotrichosis must be differentiated from other diseases with similar clinical manifestations. For example, pulmonary sporotrichosis must be differentiated from other diseases that attack the lungs, such as coccidioidomycosis and histoplasmosis, whereas osteoarticular sporotrichosis must be distinguished from diseases that affect the bones and joints, such as chronic bacterial osteomyelitis.

# Epidemiology and Demographics
Sporothrix schenckii can be found throughout the world in soil and plant matter. Peru is suspected to be an area where S. schenckii is extremely common in the environment. Outbreaks of sporotrichosis have been documented in both developing and developed countries.

# Risk Factors
The most potent risk factor in the development of sporotrichosis is handling thorny plants, sphagnum moss, bales of hay, or any plant or plant product that can cause skin trauma. These risk factors either lead to direct inoculation or merely enable the entry of the fungus. Other risk factors include a weakened immune system, a history of alcoholism, and the handling of infected animals.  

# Natural History, Complications and Prognosis
The incubation period of sporotrichosis varies from a few days to multiple months.  Complicatiaons of sporotrichosis include bacterial superinfection and sepsis. Depending on the progression of the sporotrichosis at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as good. The presence of disseminated sporotrichosis is associated with a particularly poor prognosis among immunodeficient patients and these patients are prone to relapse.

# Diagnosis

## History and Symptoms
Symptoms of cutaneous sporotrichosis include nodular lesions on the skin, at the point of inoculation, as well as along lymph nodes and vessels. The lesion is initially small and painless, and ranges in color from pink to purple.  Left untreated, the lesion becomes larger, ulcerates, and oozes. Typically, cutaneous sporotrichosis lesions manifest in the upper extremities. Extracutaneous forms of sporotrichosis typically manifest with a broad range of unspecific clinical symptoms, frequently resulting in delayed diagnosis.

## Physical Examination
Common physical examination findings of cutaneous sporotrichosis include painless pink to purple nodular lesions or erythematous plaque on the skin, which may begin to grow, ulcerate, and drain. These lesions characteristically manifest on upper extremities. Non-cutaneous forms of sporotrichosis are not generally associated with distinctive physical findings.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of sporotrichosis include isolation of S. schenckii upon culture, molecular detection, a positive sporotrichin skin test, and techniques involving antibody detection. Definitive diagnosis of sporotrichosis occurs upon the isolation and identification of S. schenckii in culture.

## Chest X Ray
Findings suggestive of sporotrichosis on chest x-ray include the presence of cavitations, tracheobronchial lymph node enlargement, and presence of nodular lesions.

# Treatment

## Medical Therapy
Because spontaneous resolution in cases of sporotrichosis is a rarity, the majority of patients require treatment. The recommended treatment regimens are largely empirical and predominantly based upon retrospective evaluations, case study reports, and nonrandomized control trials. The predominant therapy for sporotrichosis is itraconazole, which is used as the primary treatment in immunocompetent patients, and as a suppressive therapy in immunocompromised patients. The primary line of treatment for  immunocompromised patients is amphotericin B.

## Surgery
Surgery is not the first line treatment option for patients with cutaneous sporotrichosis. Surgical therapy is usually reserved for patients with either osteoarticular sporotrichosis or pulmonary sporotrichosis.

## Prevention
There are no available vaccines against sporotrichosis. Primary prevention strategies include wearing protective clothing while engaging in high risk activities, such as handling thorny plants, sphagnum moss, bales of hay, or any plant or plant product that may potentially cause skin trauma, limiting handling of sphagnum moss, and avoiding physical contact with infected animals, namely felines.