Faculty Bibliography

Bodies have continuous reticular networks, comprising collagens, elastin, glycosaminoglycans, and other extracellular matrix components, through all tissues and organs. Fibrous coverings of nerves and blood vessels create structural continuity beyond organ boundaries. We recently validated fluid flow through human fibrous tissues, though whether these interstitial spaces are continuous through the body or discontinuous, confined within individual organs, remains unclear. Here we show evidence for continuity of interstitial spaces using two approaches. Non-biological particles (tattoo pigment, colloidal silver) were tracked within colon and skin interstitial spaces and into adjacent fascia. Hyaluronic acid, a macromolecular component of interstitial spaces, was also visualized. Both techniques demonstrate interstitial continuity within and between organs including within perineurium and vascular adventitia traversing organs and the spaces between them. We suggest that there is a body-wide network of fluid-filled interstitial spaces that has significant implications for molecular signaling, cell trafficking, and the spread of malignant and infectious disease.

Background: Neuroendocrine tumors (NETs) have been well studied and most organs have criteria which allow for neuroendocrine hyperplasia (NH) or a preneoplastic state before a neuroendocrine proliferation is defined a neuroendocrine tumor. In the lung, neuroendocrine proliferations <5mm are designated tumorlets. In the stomach, neuroendocrine proliferations range from NH to neuroendocrine dysplasia, and the designation of NET does not occur unless the proliferation is >5mm. In the pancreas, neuroendocrine proliferations with a diameter of <5 mm are termed neuroendocrine microadenomas. However in the appendix, there is no provision for NH and there are no established minimal size criteria for appendiceal NETs in the current 5th edition WHO book, which considers all NETs to have malignant potential. Also the current CAP protocol applies to all appendiceal NETs regardless of size, forcing pathologists to diagnose NETs despite studies demonstrating small appendiceal NETs (<1cm) to be indolent.
Design(s): A single institution database of adult patients with appendectomies containing the word "neuroendocrine" and "carcinoid" was queried from January 2004 to December 2012. Patients with neuroendocrine carcinoma, goblet cell carcinoid, and patients without follow up were excluded.
Result(s): 32 patients were included in the study. The mean age at diagnosis was 40.3 years (18-79). Females represented 59.3 % (19/32) of all patients. All appendiceal NETs were incidentally identified in a background of acute appendicitis. Tumor size ranged from 1 mm to 17 mm and the depth of extension ranged from submucosa to mesoappendix. One patient underwent a right hemicolectomy because of tumor size > 1cm. In long term follow up (7-15 years), none of these patients had disease recurrence. (Table presented)
Conclusion(s): The majority of appendiceal NETs are small incidental findings associated with acute appendicitis. In this setting, neural proliferation and mucosal expansion can often be seen and it is reasonable for NH to also represent inflammatory/reactive changes rather than a neoplastic process given their indolent behavior and long term survival rate (100%). In the appendix, we propose NH is part of the inflammatory process and should not be classified as a NET unless it is >5mm. We advocate the terminology of appendiceal NH in neuroendocrine proliferations <5mm in keeping with size criteria in other organs. This change in terminology from NET to NH may reduce unnecessary medical surveillance, overtreatment, and patient anxiety

Background: Fibroconnective tissues of the body are traditionally conceived as layers of densely compacted collagen. Recent in vivo microscopy, however, demonstrates that at least some, including visceral submucosae, dermis, fascia, adventitia and perineurium, are actually a reticular network of fluid-filled sinuses supported by a complex scaffold of thick collagen bundles (Benias et al Sci Rep 2018: 8). The interstitial fluid is rich in hyaluronic acid (HA). Whether these large scale interstitial spaces are continuous between tissues/organs or separate is unclear. Continuity was investigated by two methods: 1. movement of non-biological pigment (tattoo pigment, colloidal silver) in colon and skin specimens; 2. localization of HA by IHC.
Design(s): H&E-stained sections of FFPE tissues from resected colons following endoscopic submucosal tattoo for malignant polyps (n=5) and from skin biopsies with either cosmetic tattoos (n=3) or colloidal silver (n=2) were examined. Location of particles was assessed. The slides were then scanned, decolorized, and stained by multiplex chromogenic IHC assay (Discovery Ultra, Ventana) for HA-binding protein (brown), vimentin (magenta) and CD34 (teal) to label interstitial lining cells.
Result(s): Tattoo pigment and colloidal silver within the interstitial spaces was identified in the dermis (Fig. 1) and colonic submucosa and in the dependent mesenteric and subcutaneous fascias. In all colon specimens HA IHC highlighted the spatial continuity of all layers of the colon from lamina propria through muscularis mucosae to submucosa (Fig. 2A), then through the muscularis propria into mesenteric fascia (Fig. 2B, C). Continuity between these spaces and perivascular stroma/adventitia and perineurium in the bowel wall was also evident. Continuity of HA-filled spaces is also demonstrated from papillary to reticular dermis and then to subcutaneous fascia interface. (Figure presented)
Conclusion(s): Interstitial spaces are neither virtual nor a result of processing artifact, but are filled with physiologically relevant fluid rich in HA. Their continuity across tissue compartments is demonstrated by movement of non-biological pigments and by spatial continuity of HA. The implications of such multisystem continuity are protean, but may particularly explain commonly observed modes of discontinuous cancer spread through tissue planes, such as mesenteric tumor deposits in colon cancer and subcutaneous in-transit melanoma metastasis, and spread of infection (e.g. necrotizing fasciitis)

AIMS/OBJECTIVE:While dysplasia in colonic sessile serrated adenoma/polyps (SSAs) often shows loss of MLH1 on immunohistochemistry, the significance of loss of MLH1 expression in non-dysplastic crypts in these polyps is less well studied. The purpose of this study was to evaluate the prevalence of MLH1 loss in non-dysplastic crypts in SSAs, and to evaluate its significance with regard to progression of these polyps. METHODS AND RESULTS/RESULTS:400 SSAs including 158 SSAs without dysplasia, 219 SSAs with dysplasia (SSAD), and 23 SSAs with invasive adenocarcinoma (SSAC) were evaluated immunohistochemically for MLH1 loss in both non-dysplastic and dysplastic portions of the polyps. 71 of 400 (18%) SSAs showed loss of MLH1 in non-dysplastic crypts. The prevalence of MLH1-deficient non-dysplastic crypts was higher in polyps with dysplasia or carcinoma (7%, 22%, and 52% in SSAs, SSADs, and SSACs, respectively; p<0.0001). When SSAs with MLH1-deficient vs. MLH-1-proficient dysplasia were compared, those with MLH1-deficient dysplasia were more likely to have MLH1-deficient non-dysplastic crypts (66% vs. 8.1%, p<0.0001) and a greater number of discrete foci (3.6 vs 1.1 foci, p=0.008). Also, non-dysplastic crypts with MLH1 loss were more likely to be contiguous to dysplasia when the dysplasia also showed MLH1 loss (26% vs 0%, p=0.02). CONCLUSIONS:Our results suggest that loss of MLH1 in non-dysplastic crypts in SSAs precedes the development of MLH1-deficient dysplasia and adenocarcinoma and may be a biomarker of an advanced serrated polyp even in the absence of dysplasia.

Weight loss through lifestyle intervention remains the mainstay treatment for nonalcoholic steatohepatitis (NASH). Nevertheless, only a minority of patients undergoing lifestyle intervention are able to achieve the weight loss threshold that reverses NASH histologic features. This case report demonstrates a minimally invasive method of treating NASH using an intragastric balloon. With endoscopic ultrasound-guided liver biopsy at the time of intragastric balloon removal, we demonstrate a significant improvement in NASH histologic features including steatosis, ballooning, lobular inflammation, and fibrosis. This endoscopic method may offer an alternative solution to patients with NASH who fail lifestyle intervention.

OBJECTIVES/OBJECTIVE:ERBB2 (human epidermal growth factor receptor 2 [HER2]) amplification/overexpression in colorectal carcinomas (CRCs) may predict response to HER2 inhibitors. We correlated ERBB2 amplification by next-generation sequencing (NGS) with HER2 overexpression by immunohistochemistry. METHODS:NGS was performed on specimens containing 20% or more tumor. HER2 immunohistochemistry (clone SP3) was scored semiquantitatively by H-score. ERBB2 fluorescence in situ hybridization (FISH) was performed to examine copy alterations in one HER2-heterogeneous tumor. RESULTS:ERBB2 amplification was detected in 2% of 1,300 CRCs analyzed by NGS. HER2 immunohistochemistry was examined in 15 cases with ERBB2 amplification (six or more copies), 10 with low gain (three to five copies), and 77 copy neutral. ERBB2 amplification and HER2 immunohistochemistry showed perfect concordance at an H-score of 105 or more. FISH confirmed homogeneous ERBB2 amplification in a tumor showing HER2 protein expression heterogeneity. ERBB2 amplification anticorrelated with RAS/RAF mutations (P = .0001). No ERBB2-amplified cases showed mismatch repair deficiency. CONCLUSIONS:NGS-detected ERBB2 amplification highly correlates with HER2 overexpression in CRC, but immunohistochemistry is required to capture protein-level heterogeneity.