Close margin of adverse histologic factors with a negative primary tumor margin is not associated with increased locoregional recurrence in colon cancer.

PURPOSE: Locoregional recurrence after resection of colon cancer is increased when primary tumor margin is positive (<1 â€‹mm). Data is limited regarding the risk of locoregional recurrence with close margin (<1 â€‹mm) of histologic factors, such as intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension. We hypothesized that close margin of these factors doesn't affect locoregional recurrence. METHODS: A retrospective review of all colon cancer surgical resections for adenocarcinoma from 2007 to 2020 was performed. Inclusion criteria were specimens with a negative primary tumor margin but a close margin of adverse histologic factors, defined as intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension within 1 â€‹mm of a mesenteric or circumferential margin. RESULTS: Among 4435 pathology reports reviewed, 45 (1 â€‹%) of cases met inclusion criteria. Average follow-up was 38 months. The adverse histologic factor was identified as intranodal tumor in 24 (53 â€‹%) cases, intravascular tumor in 8 (17.8 â€‹%), tumor deposits in 5 (11.1 â€‹%), and more than one pathologic feature in 6 (13.3 â€‹%). There were 9 (20 â€‹%) recurrences; 6 (13 â€‹%) had distant recurrences only, 2 (4 â€‹%) patients had locoregional recurrences only, and 1 (2 â€‹%) patient had both locoregional and distant recurrence. The adverse histologic factor in these three patients was intravascular in two and both intravascular and intranodal in one. CONCLUSION: Based on our results, we do not have evidence that the presence of intravascular tumor, intranodal tumor, tumor deposits, or extranodal extension within 1 â€‹mm of a mesenteric or circumferential margin is associated with increased risk of locoregional recurrence.

Acellular mucin in lymph nodes isolated from treatment-naïve colorectal cancer resections: a clinicopathologic analysis of 16 cases.

Lymph nodes with acellular mucin harvested from treated colorectal cancers (CRC) are staged as pN0. However, there is variability among pathologists while reporting the pN stage when acellular mucin is found within nodes of untreated CRCs. While the UICC guidelines suggest staging them as pN1, the AJCC and CAP do not offer any recommendations. In order to characterize their clinicopathologic features and outcome, we compared 16 untreated CRCs (study group; mean age: 68 years) harboring nodes with acellular mucin with 34 pN0 and 25 pN1 untreated CRC controls. All tumors were unifocal; 12 (75%) were right-sided lesions. Most cases (75%) showed one node with acellular mucin (range: 1-3). MMR-deficient tumors were significantly more common in the study group (83%) compared to pN0 (33%; p = 0.006) and pN1 controls (8%; p < 0.001). The overall survival of study group patients was closer to pN0 compared to pN1 controls; however, this difference was not statistically significant. In conclusion, untreated CRC that harbor acellular mucin within lymph nodes commonly present as right-sided, MMR-deficient tumors in older women that show a non-mucinous phenotype. While the limited number of cases precludes us from making any formal recommendations about staging, we suggest that the finding of acellular mucin in a node should prompt evaluation of deeper levels (with or without cytokeratin immunohistochemistry) and submission of all pericolonic fat for additional lymph node harvest. Whether acellular mucin in nodes of untreated CRCs is related to the indolent biology of the disease, a robust local immune response or MMR deficiency requires further investigation.

Distinguishing clear cell renal cell carcinoma, retroperitoneal paraganglioma, and adrenal cortical lesions on limited biopsy material: utility of immunohistochemical markers.

Retroperitoneal recurrence of clear cell renal cell carcinoma (CCRCC) after surgical resection is often investigated by needle biopsy and frequently requires immunohistochemistry to distinguish from other lesions with similar histology. This study explores the diagnostic utility of a panel of immunohistochemical markers and emphasizes potential pitfalls in dealing with this differential diagnosis. A tissue microarray with 1 mm tissue cores was constructed to include 21 CCRCC, 19 adrenocortical lesions, and 15 retroperitoneal or mediastinal paragangliomas. Triplicate cores were used for each case. The tissue microarray was then immunostained with epithelial, RCC, adrenocortical, and neuroendocrine markers. Pancytokeratins AE1/3, CAM5.2, and epithelial membrane antigen were positive in 52.4%, 66.7%, and 61.9% of CCRCC cases. Three (14.2%) CCRCC cases were negative for all 3 epithelial markers. AE1/3 and epithelial membrane antigen were negative in all adrenocortical lesions and paraganglioma cases, whereas CAM5.2 was positive in 78.9% of adrenocortical lesions and 6.7% of paragangliomas. RCC markers, including RCC Ag, CA9, and CD10, were positive in 76.2%, 85.7%, and 100% of CCRCC cases and were negative in all adrenocortical lesions and paragangliomas. Calretinin and Melan-A were positive in 100% and 94.7% of adrenal, 0% and 14.3% of CCRCC, and 26.7% and 26.7% of paragangliomas. Epithelial markers may be entirely negative in CCRCC, whereas pancytokeratin CAM5.2 is often positive in adrenocortical lesions. Furthermore, neuroendocrine markers are frequently positive in adrenocortical lesions. Therefore, a panel of, rather than single, epithelial, "CCRCC-specific," adrenocortical and neuroendocrine markers should be applied in the differential diagnosis of CCRCC, adrenocortical lesions, and paragangliomas.