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.