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.

Morphological factors as indicators of malignancy of squamous cell carcinomas in cattle exposed naturally to bracken fern (Pteridium aquilinum).

Squamous cell carcinomas (SCCs) of the upper digestive tract (UDT) of cattle have been associated with chronic bracken fern (Pteridium aquilinum) toxicity and infection with bovine papillomavirus type-4. These tumours share some morphological similarities with human head and neck SCCs. In this study, morphological changes were correlated with the biological behaviour of 40 alimentary SCCs in cattle grazing on pastures with high bracken content. The majority of SCCs were localized to the cranial and caudal regions of the UDT (almost 45% each). More than 60% of the tumours were well differentiated and were found mostly in the cranial region. Metastasis occurred in 58% of the cases, mostly to regional lymph nodes. All poorly differentiated SCCs had evidence of metastasis. Morphological patterns characterized by islands and ribbons of neoplastic keratinocytes were more prominent in well differentiated SCCs. These patterns varied greatly in moderately differentiated SCCs. Poorly differentiated tumours were characterized by the presence of cellular aggregates and individual cells and these tumours had more marked desmoplasia. A significant positive association was established between lymphoplasmacytic inflammatory infiltration and tumour-associated tissue eosinophilia. Evaluation of argyrophylic nucleolar organizer regions (AgNORs) revealed higher proliferation indices in poorly differentiated tumours than in moderately or well differentiated lesions. There was significant correlation between the AgNOR index and histological grading. The morphological factors analyzed were all related to histological grading, which is the major factor predicting the biological behaviour of SCCs in cattle naturally exposed to bracken fern.