Conjunctival rhinosporidiosis in a temperate climate

Conjunctival rhinosporidiosis in a temperate climate

INITIAL PRESENTATION

Chief Complaint

Left medial canthal lesion for the past one month

History of Present Illness

A 27-year-old male patient was referred to the Oculoplastics clinic at the University of Iowa Hospitals and Clinics for evaluation of a left medial canthal lesion. The patient was unsure of the exact length of time the lesion had been present, but he first noticed it about one month prior to presentation. He reported that he had been unconcerned until a friend noted that it was getting bigger. The patient denied any blurriness or change in vision. He also denied pain, bleeding, drainage, or tearing. He presented with no other systemic symptoms, except for a recent upper respiratory infection. He denied any history of trauma, foreign travel, or close contact with animals. In retrospect, his history was notable only for swimming in stagnant water at a local rock quarry.

Past Ocular History: None

Past Medical History: None

Medications: None

Allergies: No known allergies

Family History: Non-contributory

Social History: Pertinent elements are detailed in the history of present illness.

Review of Systems: Negative except for what is detailed in the history of present illness.

OCULAR EXAMINATION

Visual Acuity with correction (Snellen)

• Right eye (OD): 20/15
• Left eye (OS): 20/15

Ocular Motility

• Full both eyes (OU)

Intraocular Pressure (IOP): (TonoPen)

• Normal OU

Pupils

• OD: No relative afferent pupillary defect (RAPD)
• OS: No RAPD

External

• Right: Normal
• Left: Normal

Slit lamp exam

• Lids/lashes: Normal OU
• Conjunctiva/sclera
• Right: Clear and quiet
• Left: pedunculated vascular lesion arising from the superior nasal conjunctiva near the caruncle but not including it (Figure 1).
• Cornea: Clear OU
• Anterior chamber: Deep and quiet OU
• Iris: Normal architecture OU
• Lens: Clear OU

Differential Diagnosis

• Pyogenic granuloma
• Squamous papilloma
• Chronic infection
• Oncocytoma
• Sebaceous adenoma
• Sebaceous carcinoma
• Squamous carcinoma
• Foreign body
• Suture granuloma
• Conjunctival cyst
• Inflamed pinguecula

CLINICAL COURSE

The patient underwent an excisional biopsy under local anesthesia. Microscopy revealed conjunctiva with mild epithelial hyperplasia and multiple sporangia in various stages of development and regeneration (Figure 2a). Inflammatory cells surrounded the sporangia, including neutrophils, lymphocytes, plasma cells, and multinucleated giant cells. Periodic acid-Schiff (PAS) stain highlighted the thick walls of the sporangia in various stages of the life cycle (Figure 2b). Mature sporangia revealed a surface pore with release of spores (Figure 2c). Gomori methenamine silver (GMS) stained the wall of the mature sporangium (Figure 2d). These findings were consisted with rhinosporidiosis.

The patient was seen in follow-up approximately 6 months later with recurrence of the lesion. At that time, repeat excision with cautery was performed. Consideration was given to dapsone treatment following the excision, but the patient declined. Follow-up 7 months later revealed no signs of recurrence.

Figure 2a. Low powered (20x) image of conjunctiva showing mild epithelial hyperplasia, multiple sporangia in various stages of development and degeneration with surrounding inflammatory cells.	Figure 2b. PAS stain 50xmag showing the thick walls of the trophocytes. Inflammatory cells surround trophocytes, including neutrophils, lymphocytes, plasma cells, and multinucleated giant cells, often in scattered granulomas. Note there is increased vascularity.
Figure 2c. H&E stain 100xmag. Mature sporangium containing and releasing endospores	Figure 2d. GMS stain 200x magnifcation

DIAGNOSIS: Conjunctival Rhinosporidiosis

DISCUSSION

Etiology

• Rhinosporidiosis is an infection caused by Rhinosporidium seeberi. R. seeberi was thought to be a fungus for nearly 100 years but has more recently been classified as a Mesomycetozoea, an aquatic protozoan parasite (1,2). Rhinosporidiosis is endemic in parts of India and Sri Lanka, but quite sporadic in other parts of the world, including the United States (3,4). Additionally most of these cases have occurred in the warmer southern climates. Epidemiological evidence points to ground water as the source of R. seeberi, but culturing of R. seeberi in vitro from presumed contaminated sources has not yielded growth of the organism. Human-to-human transmission has not been documented, either, so it is not believed to contagious (2, 5).

Pathophysiology

• Local infection from exposure to the organism appears to be implicated in the pathogenesis of R. seeberi, but thus far, it has not been possible to intentionally infect an animal model (2). Infection usually causes a chronic granulomatous reaction resulting in polypoid growths within mucous membranes (5, 6). The nasal mucosa is most often affected, but 10-15% of cases are ocular. The most frequent ocular site of infection is the conjunctiva, followed by the lacrimal sac (2). There have been a few case reports of scleral melting and staphyloma formation secondary to R. seeberi infection (7).

Signs/Symptoms

• Chronic infection of mucous membranes by R. seeberi produces polypoid mass lesions commonly arising from the nasopharynx, oral cavity, or orbit/adnexa. The lesions are usually characterized by friability and abundant vascularity. Pinpoint white spots are also commonly seen on the surface which correspond with mature sub-epithelial sporangia (2).

Diagnosis

• Diagnosis relies entirely on histopathology which demonstrates trophocytes and sporangia in various stages of development and degeneration. Infiltration of acute and chronic inflammatory cells will also be present (5,6).

Treatment

• Rare cases of spontaneous regression have been recorded (2,3). However excision with local cautery is considered the most effective treatment (8). Cautery is used to reduce the risk of recurrence which is caused by endospores being released into nearby mucosa. Medical treatment with dapsone and amphotericin B remains controversial, as determining drug sensitivity has been impossible without the ability to grow R. seeberi in vitro. However, dapsone has had some success in treating rhinosporidioisis; it is believed to act by arresting sporangia maturation (9). Recurrence rates have been noted to vary by infection site with conjunctival and lacrimal sac recurrences being relatively low compared to nasopharyngeal recurrence rates (6).