RESUMO
Background: Medullary colonic carcinoma (MCC) is a rare and distinct phenotype of colorectal cancers characterized histologically by sheets of malignant cells with vesicular nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm, exhibiting prominent infiltration by lymphocytes and neutrophilic granulocytes. We present the clinicopathologic and immunohistochemical characteristics of this rare tumor in our patient population. Methods: Eleven cases diagnosed with MCC from 1996-2020 met the diagnostic histologic criteria and had tissue blocks available for further analysis. Immunohistochemistry for mismatch repair deficiency, CDX2, synaptophysin, and chromogranin, and microsatellite instability testing by polymerase chain reaction were performed. Additional clinical information was obtained from the electronic medical records. Results: The median age at diagnosis was 69 years. MCC was more common in women (64%) than men (36%) and all (100%) cases involved the right colon. The median carcinoembryonic antigen level at diagnosis was 2.8 ng/mL. Lymphovascular invasion and perineural invasion occurred in 64% and 9% of cases, respectively. Synaptophysin and chromogranin showed no expression in any of the cases (0%), and CDX2 was only expressed in 18% of cases by immunohistochemistry. Most patients (73%) presented with stage II disease and 7 (64%) cases were microsatellite instability-high. Only lymph node metastasis showed an association with overall survival (OS) (hazard ratio 0.04, 95% confidence interval 0.0003-0.78; P=0.035). During a median follow up of 1.25 years, the median OS was not estimable as the survival curve did not reach the median point of survival, indicating that more than half of the patients were still alive at the end of the study. Conclusion: Based on our experience, neuroendocrine markers, including synaptophysin and chromogranin, are not expressed in MCC, and many patients present with early-stage disease.
RESUMO
Colorectal adenocarcinoma with enteroblastic differentiation (CAED) is a rare subtype of colonic adenocarcinoma characterized by increased α-fetoprotein (AFP) production and the expression of at least one enteroblastic marker including AFP, glypican 3 (GPC3), or Spalt like transcription factor 4 (SALL4). We report a case of a 26-year-old female who presented with low back pain and constipation which persisted despite supportive measures. Imaging revealed multiple liver lesions and enlarged retroperitoneal nodes. Tumor markers including AFP were markedly elevated. On biopsy, samples from the liver revealed infiltrating glands lined by columnar-type epithelium with mostly eosinophilic granular to focally clear cytoplasm. By immunohistochemistry, the tumor showed immunoreactivity with AFP, hepatocyte antigen, GPC3, SALL4, CDX2, SATB2, and cytokeratin 20. A colonoscopy performed subsequently revealed a mass in the sigmoid colon and biopsy of this mass revealed a similar histology as that seen in the liver. A diagnosis of CAED was made, following the results of gene expression profiling by the tumor with next-generation sequencing which identified pathogenic variants in MUTYH, TP53, and KDM6A genes and therefore supported its colonic origin. Cases such as this underscores the use of ancillary diagnostic techniques in arriving at the correct diagnosis in lesions with overlapping clinicopathologic characteristics.