Rhinosporidiosis of the lacrimal sac masquerading as chronic dacryocystitis: a rare presentation

ABSTRACT Rhinosporidiosis is a chronic infection of the mucous membrane caused by the Rhinosporiduim seeberi, which infects through transepithelial penetration. Although described worldwide, this entity is mostly found in the western hemisphere, afflicting young people, predominantly males, associated in many cases with recreational or professional contact with bath in ponds, rivers, or stagnant waters. The clinical features are varied depending on the affected membrane, in some cases mimicking other diseases postponing the correct diagnosis. Although nasal obstruction and epistaxis are the common clinical presentations in sinonasal rhinosporidiosis, patients with epiphora without a nasal mass often challenge the diagnosis. In the present case, we have documented a case of isolated lacrimal sac rhinosporidiosis masquerading as chronic dacryocystitis, which was successfully managed by endoscopic excision, accompanied by a literature review.


INTRODUCTION
Rhinosporidiosis is a chronic granulomatous disease caused by Rhinosporidium seeberi, frequently encountered in the southern zone of India and Sri Lanka. 1 The nose and nasopharynx are the most common site affected by the disease and patients usually present with a painless mass with a history of nasal bleeding. 2 It often presents as a polypoidal mass in the nasal cavity 3 . Although nasal obstruction and epistaxis are the common clinical features, the epiphora as the single symptom is a challenging diagnosis. In the present case, we have documented a case of isolated lacrimal sac rhinosporidiosis masquerading as chronic dacryocystitis, which was successfully managed by endoscopic excision. A 25-year-male patient presented to the outpatient clinic with a swelling below the medial canthus of the right eye involving the lower eyelid for 12 months ( Figure 1A). A history of epiphora was present for the last six months. There was no history of nasal obstruction or epistaxis in the past. Anterior rhinoscopy did not reveal any abnormality in the nasal cavity. Nasal patency was found to be equal in both nasal cavities. A non-contrast CT scan was suggestive of a soft tissue density in the lacrimal sac region without any erosion of the lacrimal bone ( Figure 1B).

CASE REPORT
The visual acuity was normal in both eyes. Syringing the right lacrimal passage revealed a hard stop, consistent with the obstruction of the right nasolacrimal duct. After the informed written consent, the patient was planned for endoscopic dacryocystorhinostomy (DCR). After drilling out of the ascending process of maxilla, a dilated lacrimal sac was detected. On incising the sac, a polypoidal bleeding mass was detected obliterating the whole lumen. The mass was completely excised after a gentle dissection of the sac wall. Endoscopic dacryocystorhinostomy was performed as an adjunctive procedure to maintain the lacrimal patency. The histopathology of the specimen was confirmed to be rhinosporidiosis ( Figure 2).
The patient is on regular follow in the rhinology clinic and the ophthalmology department for the past 12 months without any recurrence of the disease.

DISCUSSION
Rhinosporidiosis is a chronic granulomatous disease affecting both humans and animals, caused by Rhinosporidium seeberi. Although it was first classified under fungal disease under ICD10, it is now considered  an aquatic protistan parasite belonging to the class Mesomycetozoa 4 . The fish and the aquatic amphibians are considered the natural host of the parasite, Humans acquire the disease by accidental contact or bathing in ponds, rivers, or working in stagnant water. 5 Transmission from animals to humans often occurs through water contact. Although already encountered worldwide, it notably endemic in the Southern part of India and Sri Lanka. 6 Rhinosporidiosis was first identified in 1892, but comprehensively described in 1900 by Guillermo Seeber in a farm-worker in Argentina with impaired breathing by a nasal mass. Kuriakose 7 first described the ocular rhinosporidiosis in 1963. The nose and nasopharynx are the primary sites to be affected by the infection (78%), followed by the conjunctiva (15%). 5 The lacrimal system becomes affected in 14.3% to 59.6% of cases of ocular rhinosporidiosis. [8][9][10][11] The ocular involvement is mostly presented by a conjunctival polyp (77.6%), either in the upper or lower lid of the fornix. Approximately 26% of the cases of ocular rhinosporidiosis are associated with either nasal or conjunctival involvement. 12 Isolated lacrimal sac rhinosporidiosis is very rare in the clinical practice with only a few reports in the literature. 9,10 It is always a challenge to suspect a case of isolated lacrimal sac rhinosporidiosis as the clinical feature always resembles a chronic dacryocystitis. Radiological evaluation (CT scan /MRI) can be undertaken in selective cases to rule out a similar pathology. 13 We undertook a literature review based on the PubMed database using "rhinosporidiosis and lacrimal sac" as the keywords. A total of 29 articles were retrieved, which comprised publications from 1973 to 2019. 156 cases of lacrimal sac rhinosporidiosis have been reported and are summarized in Table 1, including the predominant symptoms, the primary site of involvement, and the various treatment protocols. From the 156 cases, the main symptom was lacrimal sac swelling, which was observed in almost all cases. Epiphora was seen in 10.25% of the cases. In our case, epiphora and lacrimal swelling were the only presenting complaints that misled the working    18,34 or sometimes it is absent. 5,15,19,20,25,36,38 The absence of lacrimal swelling could be due to the spread of infection through the peri canalicular space of the lacrimal sac without affecting the drainage pathway. 18,39 The etiological agent can reach the lacrimal sac from the nose or conjunctiva, 40 unlike the present case where the mass was found only in the lacrimal sac, without a synchronous nasal involvement. Due to the complete obstruction of the lacrimal flow, the patient presented with epiphora resembling a chronic dacryocystitis. There are various schools of thought on the possible route by which rhinosporidiosis involves the lacrimal sac. Some researchers think it spreads through the nasolacrimal duct to the lacrimal sac and others comment that it does not spread through the duct because of the presence of the valve. 16 The imaging examination of the nose and paranasal sinus is considered a key resource to diagnose patients with isolated rhinosporidiosis, as it is often mistaken with chronic dacryocystitis. On computed tomography, it appears as a homogenously enhanced mass in the inferior meatus extending to the lacrimal sac with the erosion of the adjacent bone. 41 However, in the present case, the mass was only limited to the lacrimal sac without any radiological evidence of bony erosion. Although the majority of patients with sinonasal rhinosporidiosis are diagnosed on the clinical findings, histopathology is warranted for its confirmation. 42 On histopathology, the lesion presents with a distinctive morphology, consisting of globular cysts representing the thick-walled sporangia containing more than 1000 daughter spores in different stages of development, accompanied by a mixed inflammatory infiltrate. The organism is stained by periodic acid Schiff (PAS), Gomori's methenamine silver and Mucicarmine. 22 Surgical excision with electrocautery of the base of the lesion is considered the treatment of choice for patients with sinonasal rhinosporidiosis. The majority of the patients are managed through external dacryocystorhinostomy. 21,26,28,30,31,35,37 In contrast, in the present case, the mass was excised through a transnasal endoscopic procedure, similar to the standard endoscopic dacryocystorhinostomy, as described by Gupta et al. 14 Although medical treatment cannot be denied, its role is very much limited to patients where complete surgical resection is not possible due to the systemic spread of the disease. Dapsone, because of its anti rhinosporidial activity, can be used to arrest the maturation of sporangia and to promote fibrosis in the stroma. It can be used with 100 mg once/twice daily for 3-6 months in the preoperative period to prevent the recurrence. 4,18,23,24,29 Due to the advancement of the transnasal endoscopic procedures, there has been a decrease in the disease's recurrence rate due to enhanced visualization ensuring complete removal of the disease, as observed in the present case. Dapsone was not prescribed in our present as the disease was only limited to a lacrimal sac where complete removal was ensured with the use of wide-angle rigid nasal endoscopes. Despite the low recurrence rate, each patient needs a close follow-up with routine nasal endoscopy and lacrimal patency tests to find out the early recurrence of the disease. A high index of suspicion of the disease, appropriate radiological examination, and histopathology are considered the cornerstones for the diagnosis of an isolated rhinosporidiosis of the lacrimal sac. As described in the present case, isolated rhinosporidiosis of the lacrimal sac can be a potential differential diagnosis of chronic dacryocystitis, especially with atypical presentation.

CONCLUSION
Although patients with ocular rhinosporidiosis are mostly diagnosed on the clinical findings, i.e., with nasal obstruction and epistaxis, it is often a challenge to diagnose a case where epiphora is the single complaint. In combination with the radiological and histopathological examination, a proper clinical history is mandatory for the accurate diagnosis of atypical rhinosporidiosis.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or National research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Written informed consent has been taken from the patient prior to surgery and has been informed to the Institute reviewer board.