Biopsy was performed:
Macroscopy: Rectal biopsy: 5 pale tan pieces of tissue 4-8 mm.
Microscopy: The sections show squamous glandular mucosa including a moderate amount of subepithelial connective tissue. Multiple irregular nests of moderate to markedly pleomorphic epithelial cells are seen, containing a small amount of cytoplasm, nuclear hyperchromasia and small nucleoli. There are frequent atypical mitoses and apoptosis. There is associated desmoplastic stroma. No convincing lymphovascular or perineural invasion is identified.
Conclusion: Poorly differentiated squamous cell carcinoma.