Subtitle: A thorough pathology explanation with all sporangial stages and diagnostic microscopy.

Author: PathologyMCQ Team
Category: Infectious Disease Pathology
Read time: 12 minutes

At a glance

• Chronic granulomatous infection
• Caused by Rhinosporidium seeberi
• Produces juvenile, intermediate & mature sporangia
• Mimics nasal polyps
• Requires complete excision + cauterisation

Difficulty: Moderate–Difficult

Table of contents

1. Clinical summary

A patient presents with a polypoidal reddish mass in the nasal cavity. It bleeds easily and mimics a nasal polyp.

Clinical hallmarks

• Common in India & Sri Lanka
• Linked to bathing in contaminated ponds
• Soft, friable, polypoid mass
• Symptoms: nasal obstruction, epistaxis, foreign-body sensation
• Recurrence is possible

2. Gross findings

The lesion appears as a polypoid, reddish, granular mass that bleeds easily on handling. Its strawberry-like surface is characteristic of rhinosporidiosis and is best demonstrated by the PDF Page 1 image, which serves as the ideal primary gross illustration.

3. Histopathology

Slide 1 – Squamous epithelium with sporangia

Low power shows epithelial hyperplasia (pseudoepitheliomatous hyperplasia) with multiple round cystic structures representing sporangia embedded in the stroma.

Slide 2 – Life cycle diagram

The life cycle includes:

• Juvenile sporangium (trophocyte)
• Intermediate sporangia with immature endospores
• Mature sporangia containing fully formed endospores
• Release of free endospores into host tissue

Slide 3 – Juvenile sporangium

Juvenile sporangia appear as small round structures with condensed basophilic chromatin—early stages of maturation.

Slide 4 – Intermediate sporangium

Intermediate sporangia exhibit a bilamellar wall and contain many immature endospores, showing concentric maturation.

Slide 5 – Mature sporangium

Mature sporangia display:

• Central eosinophilic mature endospores
• Peripheral immature endospores
• Thick double-layered wall

4. Microscopic description

Epithelium

• Pseudoepitheliomatous hyperplasia
• Polypoid surface

Stroma

• Multiple spherules (sporangia) in all maturation stages
• Foreign-body giant cell reaction
• Chronic inflammation

Sporangial features

• Juvenile: small, basophilic, single chromatin mass
• Intermediate: bilamellar wall, immature granular endospores
• Mature: centrally dense endospores, peripheral immature forms

5. Final diagnosis

Rhinosporidiosis (nasal mucosa)

A chronic granulomatous infection showing sporangia in various developmental stages beneath hyperplastic mucosa—classic for Rhinosporidium seeberi.

6. View the virtual slide

See if you can appreciate all the stages

7. Discussion

Etiology

Caused by Rhinosporidium seeberi, belonging to Mesomycetozoea, a group between fungi & protozoa.

Transmission

• Contaminated stagnant water
• Traumatic implantation into mucosa

Typical sites

• Nasal cavity
• Nasopharynx
• Conjunctiva

Differential diagnosis

• Nasal polyp
• Fungal sinusitis
• Myospherulosis
• Coccidioidomycosis (similar spherules but THICKER walls)

Treatment

• Surgical excision + cauterisation
• Medical therapy ineffective
• Recurrences common

8. High – yield MCQS

9. Key pearls

• Think rhinosporidiosis in polypoid nasal masses
• Look for multiple sporangial stages
• Life cycle diagram is diagnostic gold
• Treatment = excision + cautery
• Recurrences possible

10. Recommended learning