Annular Stenotic Oesophageal Squamous Cell Carcinoma in Cattle Exposed Naturally to Bracken Fern (Pteridium arachnoideum).

Oesophageal squamous cell carcinomas (SCCs) may be observed as exophytic masses or ulcerative or infiltrative endophytic neoplasms. However, in cattle, there is also an uncommon gross presentation as an annular stenotic thickening of the oesophageal wall. Thirteen cases of annular stenotic oesophageal SCC in cattle grazing in bracken fern (Pteridium arachnoideum) areas are reported. The lesions consisted of endophytic masses, focally extensive, firm and circumferential (annular) in the oesophageal wall. Pronounced wrinkling of the mucosa, with retracted uneven areas and subsequent luminal narrowing (stenosis), was observed in all cases. Papillomas and squamous intraepithelial lesions also were observed in these cases. The SCCs were graded as well differentiated (n = 7), moderately differentiated (n = 5) or poorly differentiated (n = 1). The neoplastic keratinocytes were surrounded by moderate to abundant fibrous connective tissue (a desmoplastic reaction), that was better demonstrated by Masson's trichrome stain. Picrosirius red-stained sections showed abundant collagen type I fibres, which contributed to the stenosing characteristics of this tumour. Although it might be easily misdiagnosed as oesophageal scar tissue, the oesophageal SCCs of cattle grazing bracken fern may have a distinctive gross appearance that should be included in the differential diagnosis of oesophageal stenosis.