The genetics of interdigitating dendritic cell sarcoma share some changes with Langerhans cell histiocytosis in select cases.

Histiocytic disorders have been noted to have evidence of transdifferentiation; examples of cases with combinations of different lineages have been shown. In our index case, we identified interdigitating dendritic cell (IDC) differentiation in a case of Langerhans cell histiocytosis (LCH). Little is currently known about the genetics of IDC sarcoma (IDCS) because they are exceedingly rare. Using array comparative genomic hybridization (aCGH), we evaluated 4 cases of IDCS and compared them with our index case, as well as genetic abnormalities previously found in LCH. Four cases of paraffin-embedded samples of IDCS and 1 case of LCH with IDC differentiation were evaluated using aCGH. Array CGH results showed no abnormalities in a case of LCH with interdigitating cell differentiation. In 3 of 4 cases of IDCS, genetic abnormalities were identified; 1 case had no identifiable abnormalities. Interdigitating dendritic cell sarcoma case 1 had gains of 3q and 13q; IDCS case 2 had trisomy 12; IDCS case 3 had deletions of 7p, 12p, 16p, 18q, 19q, and 22q; and IDCS case 4 had no detectable abnormalities. Our index case, LCH with IDC differentiation, showed no abnormalities by aCGH. A number of LCH cases do not have detectable genetic abnormalities. In contrast, 3 of 4 cases of IDCS evaluated had identifiable abnormalities by aCGH. Furthermore, 2 of these shared abnormalities, albeit of large genetic regions, with published abnormalities seen in LCH. No recurrent abnormalities were identified in the IDCS cases. However, the possibility of a relationship between IDCS and LCH cannot be entirely excluded by these results.

EMR for Barrett's esophagus-related superficial neoplasms offers better diagnostic reproducibility than mucosal biopsy.

BACKGROUND: EMR of Barrett's esophagus (BE)-related superficial neoplasms represents an efficacious staging modality. It also allows for better pathologic grading compared with mucosal biopsy specimens. However, the interobserver variation in the interpretation of EMR specimens has not been tested. OBJECTIVE: To evaluate consistency in the diagnosis of BE-related neoplasia on EMR specimens. DESIGN: Nine pathologists reviewed 25 esophageal EMR specimens and corresponding biopsy specimens independently. Each pathologist classified the cases as either non-neoplastic BE, low-grade dysplasia, high-grade dysplasia, intramucosal adenocarcinoma, or invasive adenocarcinoma. Interobserver concordance for both specimens from EMRs and biopsies was measured by intraclass correlation and Kendall's coefficient of concordance. The proportion of agreement was also calculated for each specimen and compared for EMR and biopsy by using the Wilcoxon signed rank test. SETTING: Teaching hospitals. PATIENTS: Twenty-five patients who underwent EMR for BE-related neoplasia. RESULTS: The intraclass correlation and the Kendall's coefficient for the 25 biopsy specimens was 0.938 (95% CI 0.880-0.965) and 0.677, respectively; for the 25 EMRs, these were significantly improved, at 0.977 (95% CI 0.957-0.987) and 0.831, respectively. In addition, the proportion of agreement for EMR specimens was significantly better compared with biopsy specimens (P = .015). CONCLUSIONS: Interobserver agreement of BE-related neoplasia on EMR specimens is significantly higher compared with biopsy specimens. The results may relate to the larger tissue sampling compared with biopsy specimens and the ability to evaluate mucosal landmarks, such as double muscularis mucosae. Thus, we suggest that EMRs, in addition to being a staging and therapeutic procedure, improve diagnostic consistency.