Discussion
This case report from Central Tanzania at the largest zonal referral hospital has documented a case of synchronous nasal rhinosporidiosis and inverted papilloma in a paediatric patient and so far the first documented case of synchronous nasal rhinosporidiosis and inverted papilloma both in Central Tanzania and countrywide. Though sporadic, nasal rhinosporidiosis has been reported from about 70 countries with variable geographical features.12 Migration has attributed to the infrequently isolated cases in other parts of the world.37,38
Nasal rhinosporidiosis is reported to be more common in younger age groups and also predominant in men with male to female ratio being 4:1.1,9-11 Such male predominance has been observed in our case report since the affected patient was a 7-year old boy.
The disease itself, nasal rhinosporidiosis and its causative organism, Rhinosporidium seeberi have been known for over ten decades and it’s a rare infective chronic granulomatous disease of the nose.1,3 On the other hand, attempts to isolate the causative organism in vitro to date has never been successful and its taxonomic rank remains unclear.39
Being related to a group of fish parasites referred to as the DRIP clade, most pathologists and microbiologists initially considered it to be fungus on the basis of its characteristic to be stained by fungal stains such as Gomori methenamine silver (GMS) and periodic acid-Schiff (PAS).17
Available literatures have shown some authors ending up proposing the class of Rhinosporidium seeberi to be Mesomycetozoa.14,40 Regarding the natural habitat for Rhinosporidium seeberi, water reservoirs and soil contaminate by wastes are the known habitats and this has been supported by fluorescent in-situ-hybridization techniques.40 On top of that, other aquatic microorganisms might be relevant to a possible synergistic action in the establishment of natural rhinosporidiosis.40
The class Mesomycetozoa has two orders, which are the Dermocystida and the Ichthyophonida. In the order Dermocystida is the family Rhinosporideaceae that includes Rhinosporidium seeberi, Dermocystidium spp. and the rosette agent.1,40
Pertaining the route of transmission for Rhinosporidium seeberi, it is still unclear to date on the route of transmission of the organism. Despite the unclear route of its transmission there is a presumed mode of infection from the natural aquatic habitat of Rhinosporidium seeberi through a traumatized epithelium commonly called trans epithelial infection and this is most common in the nasal cavity.1,10 On the other hand the various modes of spread of Rhinosporidium seeberi includes; auto-inoculation through spillage of endospores from polyps after trauma or surgery, haematogenous spread to distant sites, lymphatic spread and sexual transmission.10,40
The notable prevalence of Rhinosporidiosis is marked in rural settings, particularly among people working or in contact with contaminated soil, stagnant water (ponds, or lakes) or sand.40 In our case report, the patient from a rural area reported a history of contact with contaminated pond water. Moreover, the patient reported a history of contact with feces of infected livestock and used to work in contaminated agricultural fields. Similar risk factors have been documented in the reviewed literatures.17,40
Whereas several hundred people bathe in stagnant water, only few develop a progressive pattern of the disease thus implying existence of predisposing factors in the host where the possibility of nonspecific immune reactivity in the host, blood group and HLA types has been suggested as important in the pathogenesis of Rhinosporidium seeberi and also in the establishment of an initial focus of infection.1,17
Rhinosporidiosis manifests as tumor-like masses, usually of the nasal mucosa or conjunctivae of humans and animals and patients with nasal involvement often have masses leading to nasal obstruction or bleeding due to polyp formation and it can spread to the nasopharynx, oropharynx, and the maxillary antrum.4,10 The patient we are hereby reporting had an isolated friable mass localized in the nasal cavity with no involvement of other anatomical sites such as maxillary sinus. The diagnosis of Rhinosporidiosis is established by observing the characteristic appearance of the organism in tissue biopsies and computerized tomography (CT) scans. The lesion is friable, vascular pedunculated or sessile polyp with a surface studded with tiny white dots due to spores beneath the epithelium, giving a ‘ strawberry-like ’ appearance.1 The lesion in our case report was similarly friable.
Systemic manifestation of rhinosporidiosis is rare and include multiple mucocutaneous, hepatic, renal, pulmonary, splenic or bone lesions associated with fever, wasting and even death.1,16,17
Despite being a rare occasion, spontaneous regression of Rhinosporidial growths has been reported in animals and humans and therefore, medical and/or surgical intervention is necessary.1,16,17
The treatment of choice for rhinosporidial growths remains to be wide local surgical excision and this reduced its recurrence rate.1,12 Surgical removal of the lesion with cauterization of the attachment base is almost curative in at least 90% of the cases.12,41 Wide local surgical excision may be associated with remarkable morbidity due to hemorrhage and septal perforation and therefore limited surgical excision and adjuvant medical therapies, including antifungals such as griseofluvin and amphotericin B, trimethoprim-sulphadiazine, and sodium stibogluconate have been tried with varied success. All drugs are endospore-static rather than endosporicidal.1,17
The only drug appearing to have clinical promise is Dapsone since it arrests the maturation of sporangia and promotes fibrosis in the stroma when used as an adjunct to surgery.1,40 It could therefore be expected that pre-surgical Dapsone would minimize both hemorrhage by promotion of fibrosis as well as preventing the colonization and infection of new sites after the release of endospores from the surgically traumatized polyps.42,43 Laser excision is becoming promising as a mainstream treatment of sinonasal rhinosporidiosis in the future.44 Our patient was kept on dapsone for 6-months after endoscopic nasal mass excision with no recurrence after 6-months of follow up.
Inverted papilloma describes the histological tendency of the epithelium inverting into the stroma. It has a characteristic and intact basement membrane that separates the epithelial component from the underlying connective tissue stroma.20 Similar to the recurrence tendency being exhibited by nasal rhinosporidiosis, inverted papilloma has recurrence tendency, local aggressiveness or destructive potential45 and association with sinonasal polyposis.25 Inverted papilloma has a tendency of malignant transformation where about 9% of inverted papillomas transform to malignant tumors and hereby the most frequent malignant tumor derived from inverted papilloma is squamous cell carcinoma.46,47 The prognosis of squamous cell carcinoma (SCC) in inverted papillomas is poor with 5- and 10-year survival rate being 39.6% and 31.8% respectively. The poor prognostic indicators of SCC following inverted papillomas include elderly age, infiltration of the skull base or orbital involvement and moderate to poor differentiation histological pattern.47,48
Human papillomavirus type 11 has been implicated in the pathogenesis of inverted papillomas. A preponderance of HPV type 6 and 11 has been detected in inverted papillomas compared to types 16 and 18. Low-risk or high-risk co-infections are rare.31,32 The clinical presentation of inverted papilloma includes nasal obstruction, epistaxis, nasal discharge and recurrent sinusitis and computerized tomography findings depict chronic osteitis and hyperostosis preoperatively.49 The clinical features of inverted papillomas resemble those of nasal rhinosporidiosis. The main stay of treatment of inverted papilloma is surgical excision of the nasal mass followed by postoperative follow up similar to nasal rhinosporidiosis due to risk of recurrence.36