Chronic mechanical irritation as a potential contributor to nasal fibroma formation in a captive Javanese cownose ray (Rhinoptera javanica).

INTRODUCTION: Rays rarely develop neoplasia in nature, yet tumors have been repeatedly reported in captive individuals, suggesting environmental or species-specific factors. METHODS: We surgically removed the nasal fibroma under general anesthesia, followed by transcriptomic and histopathological analyses in a captive Javanese cownose ray (Rhinoptera javanica). RESULTS: Histopathology revealed a fibromatous lesion characterized by dense, mature collagen-rich fibrosis in the central core, accompanied by peripheral fibroinflammatory change, vascular congestion, hemorrhage, and inflammatory-cell infiltration. Exploratory transcriptomic profiling of the central fibrotic core provided complementary evidence of candidate remodeling-associated expression patterns, including increased mechanical-stimulus response and epithelial proliferation terms. Together, these findings support a plausible link between repeated surface contact and chronic injury-associated remodeling of the nasal tissue. DISCUSSION AND CONCLUSION: These findings suggest that persistent mechanical stimulation in artificial environments may contribute to chronic fibrosis and fibroinflammatory tumor development. Together with the clinicopathological findings, the transcriptomic findings provide exploratory, hypothesis-generating support for a possible association between captivity-related mechanical stress and species-specific fibroma formation in the Javanese cownose ray.