What Is Rhinosporidiosis?
Rhinosporidiosis is a rare disease affecting the mucous membranes of the nasal chamber, conjunctiva, oral cavity, and, in rare cases, external genitalia. It is a chronic granulomatous infectious disease. It is caused by a fungal microorganism called Rhinosporidium seeberi. This microorganism has recently been reclassified as Mesomycetozoea in the taxonomic group. It was previously thought to be a fungus but is now considered a species at the borderline between fish and fungi. Research has shown that DNA (deoxyribonucleic acid) extracted from Rhinosporidium seeberi is of cyanobacterial origin.
What Are the Alternative Names for Rhinosporidiosis?
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Rhinosporidiosis of mucosal membranes.
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Conjunctival rhinosporidiosis.
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Water Mold.
What Is the Epidemiology of Rhinosporidiosis?
Rhinosporidiosis is rare in the United States. The disease is most prevalent in hot, tropical climate areas, especially in Central India. More than 92 percent of cases occur in the Indian subcontinent. The microorganism commonly invades the nasal passages like the nose and nasopharynx. The ocular region is affected in less than 15 percent of cases. The most common site of origin for ocular lesions is the conjunctiva and the lacrimal apparatus. Males are more commonly affected than females. Rhinosporidiosis typically occurs in the mucous membranes.
Other most common locations for rhinosporidiosis are Sri Lanka, Central Africa, Pakistan, and South America.
What Is the Etiology of Rhinosporidiosis?
Rhinosporidiosis cases are endemic to hot tropical countries. The infection is caused by Rhinosporidium seeberi. This microorganism is particularly found in stagnant water in hot climates. However, the disease is not found to be contagious. Multiple species of farm, pet, and jungle animals like cats, dogs, cattle, horses, and ducks have been reported to be infected by the infection. The first identified case of rhinosporidiosis infection is a nasal polyp.
The microorganism has been reclassified as Mesomycetozoea. Earlier, it was believed to be a fungus.
What Are the Risk Factors of Rhinosporidiosis?
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Living in a hot, tropical climate.
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Visiting or traveling to a warm climate zone.
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Endemic areas of Central India, Sri Lanka, Central Africa, and Pakistan.
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Swimming in a stagnant water body.
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Working near a pooled water source such as near paddy fields or river-sand areas.
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Traumatized mucous membrane epithelium with Rhinosporidium exposure (by water or air).
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Inhaled field dust may be contaminated by the endospores in the feces of contaminated animals.
What Are the Clinical Features of Rhinosporidiosis?
The lesion appears as a soft, flat, or pedunculated tissue mass that appears reddish in color due to high vascularity. It chiefly affects the mucous membranes of the nasal chamber and conjunctiva or the lacrimal sac. Other less common sites include lips, oral mucous membrane, epiglottis, uvula, trachea, laryngeal membrane, ear, and external genitalia. Rarely, the lesion may spread to the upper and lower extremities, trunk region, and brain. Younger people are more commonly affected than adults because they spend more time working outdoors or playing outdoor sports.
What Is the Pathophysiology of Rhinosporidiosis?
Rhinosporidiosis is an infectious polypoidal vascular soft tissue mass that occurs due to the inoculation of the pathogenic endospores into the skin after an injury or from endospore inhalation of Rhinosporidium species. The microorganism breeds in stagnant water or soil. The infection in humans is primarily transmitted through contaminated water or soil contact with an epithelial break on the skin. The highest incidence of the infection is identified in river-sand workers.
Once the inoculation of endospores occurs, they transform into juvenile trophocytes that have no endospores. These trophocytes then mature into intermediate sporangia, which are larger in size. Intermediate sporangia further convert to mature sporangia, which are larger, filled with several endospores, and contain immune cells.
After the inoculation, the multiplication of the pathogenic species occurs rapidly at the mucosal surface of the infected site. This mediates an immune response in the host, followed by hyperplasia of the epithelial cells. The chronic immune response leads to the development of a granulomatous mass, which further develops into a fibrous, multilobulated mass at the injection site.
What Are the Clinical Symptoms of Rhinosporidiosis?
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Epistaxis (bleeding from the nose).
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Anosmia (loss of smell partially or completely).
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Nasal blockage.
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Runny and flowing nose.
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Watery eyes.
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Abnormal sensitivity to light (photophobia).
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Swelling and inflammation of the conjunctival sac.
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Bloody tears in some cases.
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Itching in the eyes and nose.
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Dysphagia (difficulty swallowing).
How Is Rhinosporidiosis Diagnosed?
The diagnosis can be made by physically examining the lesions. The healthcare provider should carefully examine the lesions. The typical signs include fleshy, pinpoint white or yellow pinheads that are highly vascular and can bleed on palpation. The eyes show abnormal protrusion (proptosis). The travel and occupation history of the patient is also very important as the disease is endemic to hot, tropical weather and most common in river-sand workers or paddy farmers.
Confirmatory diagnosis is done by excisional biopsy. The excised sample is sent for histopathological diagnosis. FNAC (fine needle aspiration cytology) can also be performed to confirm the diagnosis. Immunohistochemistry can also be performed. Histopathological findings depict varying developmental stages of sporangia along with epithelial hyperplasia and chronic inflammatory cell infiltrate.
What Is the General Treatment of Rhinosporidiosis?
Surgical therapy is the treatment of choice. Cauterization of the lesion is carried out in the majority of cases to excise the lesion surgically. Electrocautery reduces the chances of bleeding in this highly friable, vascular granulomatous lesion. Another advantage of using this technique is that it restricts the release of endospores into the surrounding mucous membranes. The recurrence rate of the infection is reduced due to this technique.
Drug therapy is not generally recommended. However, medical treatment using Dapsone is reported in certain cases but as an adjunctive therapy. A dacryocystectomy is usually carried out if the lacrimal sac is involved.
Prevention is very important to minimize the recurrence of the infection. Swimming should be avoided in stagnant water.
The complications of the disease are rare. Sometimes, the infection may disseminate to limbs, the brain, or external genitalia. The lesion may even progress to osteolytic bone lesions. The brain can be infected and cause increased morbidity. Local bacterial infections secondary to the primary disease are also common complications.
The prognosis of the infection is good. Recurrence can occur, but with electrocautery, the dissemination can be minimized.
Conclusion
Rhinosporidiosis is a chronic, granulomatous infection of the mucous membranes affecting the eyes and nasal chamber. Rarely, it may progress to limbs and the brain. Sometimes, it may lead to osteolytic lesions. It is important to avoid swimming in stagnant water. Surgical intervention is the first line of treatment for the disease. The recurrence rate can be reduced by using electrocauterization.
