Conjunctival rhinosporidiosis

Rhinosporidiosis in the Americas: A Systematic Review of Native Cases

Rhinosporidiosis is a chronic mucosal infection caused by Rhinosporidium seeberi, an aquatic protistan parasite. It presents as nasal or ocular polypoidal or vascularized masses. It is endemic in tropical and subtropical areas, especially in South Asia; R. seeberi´s endemicity in the Americas is often overlooked. The objective of this study was to describe the demographic and clinical characteristics of patients with rhinosporidiosis in the Americas, its management, and patient outcomes. This study is a systematic review of cases of human rhinosporidiosis in the Americas reported in the literature from 1896 to February 28, 2019. This review screened 1,994 reports, of which 115 were eligible for further analysis. The selected reports described 286 cases of human rhinosporidiosis between 1896 and 2019. Cases were diagnosed in Brazil (32.2%), Colombia (24.4%), Paraguay (12.6%), and the United States (11.9%). The majority of the cases (91%) occurred in geographic areas with altitudes < 1,000 m above sea level and in areas with median temperatures ≥ 25°C (67.3%). Most of the patients presented nasal (65%) and ocular involvement (35%). Surgical treatment was provided for 99.6% of patients, but 19.8% of them recurred. This review describes the under-recognized geographic distribution and clinical presentation of rhinosporidiosis in the Americas and highlights clinical differences to cases in Asia, specifically in reference to a higher prevalence of ocular disease and higher relapse rates.

Conjunctival Implantation Cyst in the Orbicularis Oculi Muscle: Review of a Possible Origin From Displaced Stem Cells With a Differential Diagnosis

PURPOSE

To document a unique case of a corneal/conjunctival epithelial inclusion cyst located in the orbicularis oculi muscle with a comprehensive review of variant conjunctival cysts and simulating conditions.

METHODS

Clinicopathologic case report with detailed histopathologic and immunohistochemical evaluation for cytokeratins combined with a tabulation of mimicking lesions and relevant literature citations.

RESULTS

A 59-year-old man experienced severe blunt left periorbital trauma that resulted in a limbal partial-thickness corneal wound with an associated epithelial abrasion and a full-thickness eyelid laceration extending from the superior fornix to the margin. Several months after surgical repair of the eyelid a cyst appeared in the superior pretarsal skin. Histopathologic and immunohistochemical investigations supplied data suggesting that the cyst had a high probability of a corneoscleral limbal stem cell origin. Distinctive features of the lesion are contrasted with those of allied or simulating cysts.

CONCLUSIONS

Stem cells are now believed to be located at the corneoscleral limbus, in the inferior fornix, in the medial canthal region, and at the eyelid margin where transitions from conjunctival epithelium to epidermal epithelium occur. Due to their replicative, hardy and robust nature, stem cells displaced to alien environments are most likely to survive and produce cysts. The cyst's corneal-type cytologic characteristics, the absence of goblet cells, and the expression of a broad spectrum of cytokeratin biomarkers in the current case give support to the proposal that limbal stem cells in the region of the corneal laceration were displaced to the eyelid orbicularis muscle and were responsible for this most extraordinary cyst. Comparison with other epithelial cystic linings lends further evidence for this conclusion.