Optimization of Immunophenotypic Panel to Differentiate Upper From Lower Gastrointestinal Adenocarcinomas: Analysis of New and Traditional Markers.

Adenocarcinomas of the esophagus (EAC), stomach [gastric adenocarcinoma (GAC)], and colorectal carcinoma (CRC) frequently show similar morphology because upper gastrointestinal tumors (GITs) usually evolve from pathologies involving intestinal metaplasia. Upper and lower GIT may also show overlapping immunophenotypes when using the traditional CK7, CK20, and CDX2 panel, which in patients presenting with metastatic disease of unknown origin may lead to misdirected diagnostic workup and/or therapy. We compared the phenotype of upper and lower GIT using an expanded immunohistochemical panel that included the traditional and newer gastrointestinal markers: SATB2, DcR3, MUC5AC, and MUC6. The panel was applied to resection specimens from 40 CRC, 40 GAC, and 40 EAC. A panel using SATB2, CK7, and CDX2 provided the best discriminating power for separating upper from lower GIT and was applied to 101 biopsies including 17 EAC, 17 GAC, 19 CRC, 18 pancreatic adenocarcinomas, 15 cholangiocarcinomas, and 15 lung adenocarcinomas. The phenotype CK7/CDX2/SATB2 was moderately sensitive and highly specific of upper GIT, the phenotype CK7/CDX2/SATB2 was highly sensitive and specific for lower GIT, the phenotypes CK7/CDX2/SATB2 and CK7/CDX2/SATB2 favored pancreatobiliary or lung primaries. Less frequent phenotypes showed substantial overlap. Although strong diffuse expression of SATB2 was characteristic of CRC, weak and/or focal expression was present in one third or more of upper gastrointestinal, cholangiocarcinomas, and lung adenocarcinomas. DcR3, MUC5AC, and MUC6 improved specificity, but showed poor sensitivity, suggesting they should be used as second tier markers.

Surface Ki-67 Expression Improves Reproducibility of Dysplasia Diagnosis in Barrett's Esophagus.

OBJECTIVES: Many studies have shown poor reproducibility among pathologists for diagnosing dysplasia in Barrett's esophagus (BE). Immunohistochemical stains (IHC) are not widely used due to overlapping expression patterns in reactive and dysplastic processes. We hypothesized that markers involved in cell-cycle (cyclin D1, Ki-67, P16), differentiation/cell-cell interaction (ß-catenin, SATB2 CD44, OCT4) and senescence (γH2AX) would produce different results in reactive and dysplastic processes. METHODS: A micrograph album of 40 H&E and matching IHCs depicting optimally oriented lesions were evaluated independently by 3 pathologists. Expression was scored separately in the surface, isthmus, and base regions of the glands. RESULTS: Statistical analysis showed that surface Ki-67 expression showed the largest difference in expression and smallest P value (P < .001) for identifying dysplasia. At a cutoff level of 5% or less, negative predictive value (NPV) was 100%. κ correlation between pathologists improved from substantial to almost perfect (0.70-0.95) using ancillary surface Ki-67. CONCLUSION: A case-control study with glass slides including all diagnostic categories using this parameter confirmed improved κ correlation among pathologists (0.29 vs 0.60), better correlation with outcomes (76% vs 69%), increased odd risks (15.3) for progression in positive cases, and an improvement in sensitivity (88% vs 64%) and NPV (88% vs 73%) compared to histology alone.

Immunophenotypic Comparison of Neoplasms of the Appendix, Right Colon, and Left Colon in Search of a Site-Specific Phenotypic Signature.

Aims. The proximal colon derives from the midgut endoderm, the distal one third derives from the hindgut endoderm, and the distal anal canal is of ectodermal origin. At least 5 molecular subtypes of colorectal carcinomas (CRC) have been identified, and some have a marked preferential right-sided location. Histologically, some CRC are much more common in the appendix. We hypothesized that these findings suggest the existence of diverse molecular genetic colonic subregions and compared the expression of classic and recently discovered colorectal markers in tumors at various locations to determine if a site-specific immunophenotypic signature could be identified. Methods and Results. Immunostains for CK7, CK20, MUC2, MUC5AC, MUC6, SATB2, DCR3/TNF6B, CDX2, Ki-67, and MMR proteins were performed on 17 appendiceal low-grade mucinous neoplasms and 6 crypt cell adenocarcinomas of the appendix, 15 right-sided and 15 left-sided mucinous adenocarcinomas, 17 right-sided and 15 left-sided conventional adenocarcinomas, and 5 signet ring cell adenocarcinomas (SRCCA). Statistically significant differences in the expression of MUC2, MUC5AC, MUC6, CK7, and SATB2 by site and/or histologic type were documented. MMR deficiency showed a significant correlation with MUC5AC and MUC6 expression. DCR3, CDX2, and CK20 expression was consistent throughout the colon. A CK7+/CK20+ phenotype was most common in appendiceal tumors and SRCCA. Conclusions. Statistically significant differences in the expression of some markers by histologic type and site were documented, supporting the existence of regional molecular genetic heterogeneity in the colon that result in site-specific epigenetic susceptibilities, tumor phenotypes, and immunophenotypes.

Comparative immunomorphology of testicular Sertoli and sertoliform tumors.

Sertoli cell (SC) and sertoliform tumors of the testis are very uncommon; for this reason their differential diagnosis and classification can be challenging. We applied an extensive immunophenotypic panel that included androgenic hormones, enzymes and receptors, neuroendocrine, lineage and genitourinary markers to a series of these lesions to determine if and which immunostains can aid in their diagnostic workup. Study cases included: 2 androgen insensitivity syndrome-associated SC adenomas, 3 SC tumors (SCT) not otherwise specified (SCT-NOS), 3 sclerosing SCT, 2 large cell calcifying SCT, 1 SCT with heterologous sarcomatous elements, 1 malignant SCT, and 1 sertoliform rete testis adenoma (sertoliform RTA). We found that SCT-NOS and variants with sclerosis showed a phenotype akin to atrophic seminiferous tubules characterized by gain of expression of pankeratin, calretinin, CD56, which are negative in normal SC. Distinctive phenotypes were identified in: sclerosing SCT: androgen receptors (AR) + (strong)/PAX2/PAX8+ (subset)/S100+/inhibin-; large cell calcifying SCT: calretinin+ (strong)/S100+/AR-; sertoliform RTA: PAX2/PAX8+/pankeratin+/inhibin-. Androgenic hormones and enzymes did not show diagnostic utility. A panel of calretinin, inhibin, pankeratin, S100, PAX2/PAX8, and AR consistently allowed distinction between variants of Sertoli and sertoliform tumors.

Immunophenotypic differences between neoplastic and non-neoplastic androgen-producing cells containing and lacking Reinke crystals.

We performed a detailed morphologic, immunophenotypic, and endocrine characterization of neoplastic and non-neoplastic lesions of androgen-producing cells known to harbor or lack Reinke crystals (RCs) with an aim to provide further insight into the nature of these cells and crystals. Study cases were selected from the files of participating hospitals and subclassified according to current classifications: 20 with Leydig cell tumors (LCTs), 2 with testicular adrenal rest tumors (TARTs), 2 with testicular tumors of adrenogenital syndrome (TTAGS), and 2 with androgen insensitivity syndrome (AIS). An extensive immunophenotypic panel including markers used in sex cord-stromal cell tumors, androgen hormones, enzymes, and receptors was applied to the cases and 10 non-tumoral adrenal glands. Non-tumoral tissues were scored separately. RCs were present in 90 % of LCT cases and all cases with normal Leydig cells; RCs stained specifically with calretinin and 3ß-hydroxysteroid dehydrogenase (3BHSD) and were present only in cells with high concomitant expression of both proteins, a phenotype unique to Leydig cells and LCTs. Leydig cells from AIS cases lack RCs due to decreased expression of 3BHSD. Calretinin is decreased in testicular adrenal-like tumors and absent in normal adrenocortical cells, which explain why they lack RCs. Calretinin expression in androgen-producing cells is independent from androgen receptors and androgen synthesis. RCs represent for the most part, if not exclusively, crystallized forms of a 3BHSD/calretinin complex. Androgen-producing cells containing and lacking RCs differ mainly in the level of expression of these proteins and androgen receptors.

The mystery of the vanishing Reinke crystals.

Reinke crystals (RC) are pathognomonic of Leydig cells (LCs); they are thought to be rare in normal testes and to occur only in approximately one third of LC tumors. We noticed that crystals present in touch imprint and frozen sections of an LC tumor disappeared after tissue fixation. This phenomenon led us to hypothesize that their reported low frequency in normal and neoplastic LCs may be secondary to degradation/dissolution of the crystals after formalin fixation. Our review of the literature also led us to hypothesize that RC are better preserved after air-drying and alcohol fixation. We collected testicular samples from 21 autopsies including air-dried cytologic preparations and tissue samples that were fixed in alcohol or formalin. We found that RC are common in normal LC but dissolve rapidly in formalin and slowly and only partially in alcohol. The composition of RC is unknown; however, they have been reported to stain specifically for nestin, an intermediate filament expressed mainly in neural and muscle tissue. Because the crystals have only been described in androgen-producing cells, we hypothesized that the crystals may represent a crystallized form of androgenic hormones, hormone complexes, or enzymes involved in their synthesis. We performed immunostains for androgens and enzymes involved in androgenesis. We also performed nestin immunostain to confirm the previous study. The crystals stain specifically with antibodies anti-3ß-hydroxysteroid dehydrogenase and are negative for the remaining androgenic enzymes, androgenic hormones, and nestin.