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