Ulcerated rectal mucosal fragments infiltrated by sheets of crushed atypical medium to large -sized cells. The neoplastic cells exhibit high nuclear-to-cytoplasmic ratios, scant cytoplasm, and hyperchromatic nuclei. Frequent mitotic figures and apoptotic bodies are identified. The background stroma shows desmoplasia and foci of necrosis.
Picture is that of malignant undifferentiated large round cell tumor, recommended for typing by marker study (CD20, CD3, CK, Synaptophysin, HMB45, CD43, Ki-67).
Rectal mass
Soft tissue fragments collectively measured 1.2 cm, totally embedded.
Rectal mass, endoscopic biopsy :