PMC7233296_01
Pathology findings of a rectal NEC.. Rectal NEC pathological findings showed undifferentiated small cells with haematoxylin and eosin staining (A). Immunohistochemistry staining was positive for epithelial markers, such as cytokeratin CAM 5.2 (B), and neuroendocrine markers as synaptophysin (C). In this case, Ki-67 index >80% confirmed a high-grade poorly differentiated SCNEC subtype (D).
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The negative CDX2 staining indicated that the tumoral cells had barely intestinal differentiation, therefore supporting the final diagnosis of an infiltrating highly undifferentiated SCNEC of the rectum (Figure 2).
Pelvic MRI and dosimetry volumes for planned radiotherapy treatment.. (A). Pelvic MRI sagittal view shows the primary tumour, a 9-cm rectal mass (red arrow) infiltrating the posterior vaginal wall. (B). In the radiotherapy dosimetric view, 95% of the doses covering the involved locoregional lymph nodes are highlighted in red. (C). Pelvic CT image 2 months after radiotherapy treatment, showing a local partial response within the primary rectal tumour (red arrow).
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Figure 3A and B illustrates the baseline pelvic MRI and the radiotherapy dosimetric plan. Her first evaluation CT scan showed an overall partial response, with the disappearance of bilateral lung nodules and significant shrinkage of primary rectal tumour and pelvic lymph nodes (Figure 3C).