Rhinosporidiosis

By

Dr. T. Balasubramanian M.S. D.L.O.

Definition

Rhinosporidiosis has been defined as a chronic granulomatous disease characterized by production of polyps and other manifestations of hyperplasia of nasal mucosa. The etiological agent is Rhinosporidium seeberi.

Rhinosporidium seeberi

• Initially believed to be sporozoan

• Classified under fungus - Olipidiaceae by Ashworth

• Recently placed under DRIPS of aquatic protistan parasites

• PCR tests have not demonstrated fungal proteins

History

• .1892 - Malbran observed the organism in nasal polyp 1900 - Seeber described the organism 1903 - O'Kineley described its histology 1905 - Minchin & Fantham studied O'Kineley's tissue and named the organism as Rhinosporidium Kinealyi 1913 - ZSchokke reported similar organism in horses and named it Rhinosporidium equi 1923 - Ashworth described its life cycle 1924 - Forsyth described skin lesion 1924 - Thirumoorthy reported the first female patient 1936 - Cefferi establised the identity of R. Seeberi and R. Equi 1953 - Demellow described the mode of its transmission

Incidence / geographical description

.More than 90% of cases have been reported from India / SrilankaMadurai, Ramnad, Rajapalayam, and Sivaganga are endemic zones in TamilnaduTransmission is possibly due to taking bath in common ponds

Theories of spread

.•Demellow's theory of direct transmission •Autoinoculation theory of Karunarathnae (responsible for satellite lesions) •Haematogenous spread - to distant sites •Lymphatic spread - causing lymphadenitis (rarity)

Karunarathnae ‘s theory

.Karunarathnae postulated that Rhinosporidium seeberi existed in a dimorphic state. It existed in a saprophytic form in soil and water. It took a yeast form inside tissues. This ability to exist in dimorphic state helps it to survive hostile environment for a long period of time.

Reasons for endemicity

.•Physical characteristics of water in the ponds•Presence of synergistic aquatic organisms•Genetic predisposition in patients affected•Host immunity (lack of) or altered

Life cycle (Ashworth)

.•Spore is the basic infecting unit.•It is about 7 microns in size•Also known as spherule•It has clear cytoplasm with 15 – 20 vacuoles filled with food matter•It is enclosed in a chitinous membrane•Found only in connective tissue spaces and is rarely intracellular

Life cycle (Ashworth)

.•Spores start to increase in size•At 50 – 60 microns size granules start to appear. Nucleus prepares for cell division•Mitosis occur 4, 8, 16, 32 and 64 nuclei are formed•At 7th division size becomes 100 microns•Fully mature sporangium is 150 microns•Mature spores are found in the centre and immature ones at the periphery

Life cycle (Ashworth)

.

Life cycle (Recent)

.

•Trophozoite (Juvenile sporangium) – 6 – 100 microns•It has single nucleus at 6 µ stage / Multiple nuclei at 100 µ stage•Lipid granules are seen in cytoplasm

Life cycle (Recent)

.1. Intermediate sporangium is 100 – 150 µ in diameter2. It has bilamellar cell wall – outer chitinous and inner

cellulose3. Immature spores are seen within the cytoplasm4. There are no mature spores seem inside the cytoplasm

Life cycle (Recent)

. Mature sporangium:• 100 – 400 microns• Cell wall is thin and bilamellar• Inside cytoplasm mature and immature spores are seen• These spores are embedded in mucoid matrix• Bilamellar cell wall has one weak spot – operculum• Spores mature in centrifugal and centripetal pattern• Mature spores are covered with mucoid material (comet

of Beattee)• Mature spores give rise to electron dense granules

which are the ultimate infecting unit

Life cycle (Recent)

.

Clinical classification

.

• Nasal • Nasopharyngeal • Mixed • Bizzarre (ocular and genital) • Malignant rhinosporidiosis (cutaneous rhinosporidiosis)

Common sites affected

.

Nose - 78% Nasopharynx - 68% Tonsil - 3% Eye - 1% Skin - very rare

Features of nasal Rhinosporidiosis

• Lesions are polypoidal reddish and granular

• Lesions may be multiple, pedunculated and friable

• Surface is studded with whitish dots i.e. sporangia

• The nasal lesions are highly vascular and bleeds on touch

• The whole mass could be seen to be covered with mucous secretion

• The lesion is restricted to nasal mucous membrane and does not cross the mucocutaneous junction

Histopathology of nasal Rhinosporidiosis

• Papillomatous hyperplasia of mucous membrane with rougae formation

• Epithelium over sporangia is thinned out and giant cells could be seen in this area

• Accumulation of mucous in the crypts

• Increased vascularity due to angiogenesis factor

• These spores stain with sudan black, Bromphenol blue

Features of nasal Rhinosporidiosis

• Chronicity• Recurrence• Dissemination

Reasons of chronicity

• Antigen sequestration• Antigenic variation• Immune suppression• Immune distraction• Immune deviation• Binding of host

immunoglobulins

Treatment

• Surgery• Dapsone 100 mg /day –

6 months

.