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Objectives: Small sample size limits the number of immunostains that may be attempted in colorectal carcinoma (CRC) biopsy specimens. We investigated the utility of dual stain with special AT-rich sequence binding protein 2 (SATB2) or caudal-type homeobox 2 (CDX2) and cytokeratin 20 (CK20) or villin in identifying CRC., Methods: Tissue microarrays with 222 CRCs and 375 other carcinomas were built. Dual stain was performed pairing nuclear stains CDX2 or SATB2 with CK20 or villin., Results: All four single stains showed excellent sensitivity (93%-99%) but variable specificity (56%-88%) for CRC. All four dual stains also showed excellent sensitivity (90%-96%) while much improved specificity (88%-98%) compared with single stains. SATB2 dual stain (with CK20 or villin) showed a higher specificity than CDX2 dual stain (with CK20 or villin) with a comparable sensitivity., Conclusions: SATB2 dual stain shows the greatest potential clinical utility in identifying CRC and is superior to CDX2 dual stain. More important, SATB2 dual stain could be helpful for specimens with limited tissues or those having a nonclassic staining pattern.

Objectives: Determination of the primary site of origin for mucinous neoplasms identified in the peritoneal and/or pelvic cavities may be challenging, with major differential diagnoses including appendiceal mucinous neoplasm (AMN) and ovarian mucinous neoplasm (OMN). Special AT-rich sequence binding protein 2 (SATB2) has been shown to be highly selectively expressed in the lower gastrointestinal tract, including the appendix., Methods: We investigated the utility of a dual stain (DS) with SATB2 or caudal type homeobox 2 (CDX2) and cytokeratin 20 (CK20) or villin in distinguishing AMNs from OMNs. Tissue microarrays with 40 AMNs and 18 OMNs were stained with SATB2 or CDX2 paired with either CK20 or villin., Results: SATB2 single stain showed a good sensitivity of 83% and the highest specificity of 78% for AMNs over OMNs among all four stains. DS with SATB2 and villin showed an identical sensitivity of 78% but specificity increased to 94%, while DS with SATB2 and CK20 showed a sensitivity of 80% and a specificity of 100%. In contrast, DS with CDX2 and CK20/villin showed slightly higher sensitivity but much lower specificity., Conclusions: DS with SATB2/CK20 shows the greatest potential clinical utility in distinguishing AMNs from OMNs and is superior to DS with CDX2/CK20. Importantly, DS could be helpful for specimens with limited tissues., (© American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com)

In immunocompromised patients, oral ulcerations are common and have a wide spectrum of causes, including herpesvirus infection. We report on a case in which an oral ulcer was simultaneously infected by herpes simplex (HSV), cytomegalovirus (CMV), and Epstein-Barr virus (EBV) in a kidney-pancreas transplant recipient. A 46-year-old woman presented with a clinically nonspecific dorsal tongue ulcer of 3 months duration. Histopathologic evaluation indicated keratinocytes exhibiting herpetic viral cytopathic effect. Nuclear and cytologic alterations suggestive of CMV infection were found in endothelial cells subjacent to the ulcer. Immunohistochemistry testing for HSV and CMV was positive in these cells. Large atypical mononuclear cells were also evident in the ulcer bed's inflammatory infiltrate, which had intense nuclear positivity for Epstein-Barr encoding region in situ hybridization. We believe this is the first well-documented report of the definitive concomitant presence of HSV, CMV, and EBV in an immunocompromised patient. Although the pathogenesis of coinfected ulcers remains unknown, a synergistic effect is possible., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objectives: Somatic BRAF mutation in colon cancer essentially excludes Lynch syndrome. We compared BRAF V600E immunohistochemistry (IHC) with BRAF mutation in core, biopsy, and whole-section slides to determine whether IHC is similar and to assess the cost-benefit of IHC., Methods: Resection cases (2009-2013) with absent MLH1 and PMS2 and prior BRAF mutation polymerase chain reaction results were chosen (n = 57). To mimic biopsy specimens, tissue microarrays (TMAs) were constructed. In addition, available biopsies performed prior to the resection were available in 15 cases. BRAF V600E IHC was performed and graded on TMAs, available biopsy specimens, and whole-section slides. Mutation status was compared with IHC, and cost-benefit analysis was performed., Results: BRAF V600E IHC was similar in TMAs, biopsy specimens, and whole-section slides, with only four (7%) showing discordance between IHC and mutation status. Using BRAF V600E IHC in our Lynch syndrome screening algorithm, we found a 10% cost savings compared with mutational analysis., Conclusions: BRAF V600E IHC was concordant between TMAs, biopsy specimens, and whole-section slides, suggesting biopsy specimens are as useful as whole sections. IHC remained cost beneficial compared with mutational analysis, even though more patients needed additional molecular testing to exclude Lynch syndrome., (Copyright© by the American Society for Clinical Pathology.)