Michal Kamionek

Colitis Induces Enteric Neurogenesis Through a 5-HT4–dependent Mechanism

Background:The intestine is known to contain enteric neuronal progenitors, but their precise identity and the mechanisms that activate them remain unknown. Based on the evidence for the neurogenic role of serotonin (5-HT) in the postnatal gut and the observation of enteric neuronal hyperplasia in inflammatory bowel disease, we hypothesized that colitis induces a neurogenic response through 5-HT4 receptor signaling. Methods:We examined the effects of 5-HT4 agonism on colonic neurogenesis and gliogenesis in vitro and in vivo in adult mice using dextran sodium sulfate to experimentally induce colitis. Results:In vitro, 5-HT4 agonism led to increased neuronal proliferation and density. Induction of experimental colitis in vivo similarly resulted in increased numbers of myenteric neurons, and this was inhibited by 5-HT4 antagonism. Interestingly, both in vitro and in vivo, 5-HT4 signaling increased glial cell proliferation but did not increase glial cell numbers, leading us to hypothesize that glia may give rise to neurons. After induction of colitis in normal, Nestin-GFP and Sox2-GFP transgenic mice, it was revealed that multiple glial markers (Sox2, Nestin, and CD49b) became strongly expressed by enteric neurons. Immunoselected enteric glia were found to give rise to neurons in culture, and this was inhibited in the presence of 5-HT4 blockade. Finally, isolated glia gave rise to a neuronal network upon transplantation into aganglionic embryonic avian hindgut. Conclusions:These results show that colitis promotes enteric neurogenesis in the adult colon through a serotonin-dependent mechanism that drives glial cells to transdifferentiate into neurons.

Significance of Proximal Margin Involvement in Low-Grade Appendiceal Mucinous Neoplasms

CONTEXT Appendiceal adenomas and low-grade appendiceal mucinous neoplasms (LAMNs) confined to the appendix are cured by appendectomy. However, involvement of the proximal margin raises concern for residual disease. Some patients with a positive margin at appendectomy undergo cecal resection to eliminate a perceived risk for tumor recurrence or dissemination, although that likelihood is assumed rather than demonstrated. OBJECTIVE To determine whether involvement of the proximal appendiceal resection margin by adenoma or LAMN is a risk factor for local development of recurrence or pseudomyxoma peritonei. DESIGN Appendiceal adenomas and LAMNs confined to the appendix were considered for the study if they showed neoplasia or dissecting mucin at the proximal margin. The presence or absence of residual tumor in cecal resections was determined. Follow-up data were obtained from clinical records. RESULTS Sixteen patients (14 female, 2 male) with LAMN (n = 15) or adenoma (n = 1) and an involved proximal resection margin were identified, including 9 with neoplastic epithelium within the lumen and 7 with acellular mucin in the appendiceal wall at the margin. Six patients underwent cecal resection and the others were nonsurgically followed. No cecal resection had residual neoplasia. No patient developed recurrence or pseudomyxoma peritonei (mean follow-up, 4.7 years). CONCLUSIONS In patients with LAMNs confined to the appendix, involvement of the appendectomy margin by neoplastic epithelium or acellular mucin does not predict recurrence of disease, even without further surgery. A conservative approach to managing these patients can be justified.

BRAF V600E immunohistochemistry is reliable in primary and metastatic colorectal carcinoma regardless of treatment status and shows high intratumoral homogeneity.

In colorectal carcinoma the evaluation of BRAF mutation status is increasingly being performed given its utility as a prognostic and predictive biomarker. However, there are conflicting reports of the sensitivity and specificity of BRAF V600E immunohistochemistry (IHC), and little is known about its reliability in tissues collected from metastatic sites or after chemotherapy, radiation therapy and/or targeted therapy. The degree of intratumoral staining heterogeneity is also not well established. We performed IHC for BRAF V600E (VE1) on 204 cases of colorectal carcinoma including 59 with the BRAF V600E mutation. These included primary (n=147) and metastatic/recurrent (n=57) tumors, collected before (n=133) or after (n=71) chemotherapy, radiation therapy and/or targeted therapy. Evaluation of a test cohort (39 cases) with knowledge of mutation status established a specific staining pattern for the mutation: diffuse cytoplasmic staining of near-uniform intensity, regardless of strength of staining. Using this pattern, pathologists at 3 levels of training independently performed blinded evaluation of the remaining cases. BRAF V600E staining was 96.3% sensitive and 98.5% specific for the mutation, including both pretreatment and posttreatment specimens. Fleiss &kgr; for interobserver agreement was 0.96. Staining of whole sections of the BRAF mutants showed diffuse staining in all cases and uniform or near-uniform intensity in 91%. In 20 cases with both pretreatment and posttreatment specimens, there was 100% accuracy and agreement in staining between samples. We conclude that BRAF V600E IHC is reliable for the evaluation of mutational status in colorectal carcinoma regardless of site or prior treatment history, and staining shows a high degree of intratumoral homogeneity.

Mutually exclusive extracellular signal-regulated kinase pathway mutations are present in different stages of multi-focal pulmonary Langerhans cell histiocytosis supporting clonal nature of the disease

Pulmonary Langerhans cell histiocytosis (PLCH) is an idiopathic cigarette smoking‐related disorder of the lung. Molecular changes in cellular or fibrotic stages of PLCH have not been investigated. We studied the prevalence of extracellular signal‐regulated kinase (ERK) pathway mutations in different PLCH stages and other non‐PLCH smoking‐related lung diseases.

Interinstitutional Whole Slide Imaging Teleconsultation Service Development: Assessment Using Internal Training and Clinical Consultation Cases

CONTEXT Assessment of accuracy and feasibility of whole slide imaging (WSI) for interinstitutional consultation in surgical pathology. OBJECTIVES To train technical and pathologist staff in WSI technology, establish and evaluate a WSI workflow using training cases and second-opinion consultations, and assess diagnostic accuracy. DESIGN First, WSI training and evaluation using selected subspecialty service cases were performed and compared with the clinical glass slide (GS) diagnosis. Second, WSI and GS diagnoses of consecutive, second-opinion consultation cases were compared. Discrepancies underwent adjudication to determine a reference diagnosis. Participant observations on WSI initiation to practice were gathered. RESULTS There were 130 cases evaluated, with 123 correlations (94.6%) and 6 minor (4.6%) and 1 major (0.8%) discrepancies. The 74 consultation cases interpreted had 52 correlations (70.3%), and 18 minor (24.3%) and 4 major (5.4%) discrepancies. The WSI and GS adjusted major discrepancy rates in second-opinion consultations were 2.7% (2 of 74) and 4.1% (3 of 74), respectively. Statistical analysis showed that WSI was not inferior to GS interpretation. Pathologists agreed the software was easy to use and the images were adequate, but more time was spent rendering WSI interpretations. CONCLUSIONS A significant learning curve was observed in the transition from the training set to clinical consultation cases associated both with WSI interpretation and adjustments to the digital analogs of routine GS workflow. Results from second-opinion consultations indicated that WSI interpretation was as accurate as GS interpretation among properly trained and experienced users. Overall, WSI-based practice appears feasible for second-opinion consultations.

Syphilis presenting as inflammatory tumors of the liver in HIV-positive homosexual men.

Syphilis, a sexually transmitted infection caused by the spirochete Treponema pallidum, has seen a resurgence since 2001, particularly in men who have sex with men. Syphilis can affect the liver during the secondary stage as syphilitic hepatitis and during the tertiary stage as gummas. We describe 3 cases of syphilis in human immunodeficiency virus–positive homosexual men that presented as hepatic mass lesions clinically suspected of being malignant tumors. Histologically, 2 of the 3 cases showed a plump spindle cell proliferation, mixed inflammatory infiltrate with numerous neutrophils, and abscesses, whereas the third case showed granulomas and pericholangitis/cholangitis. Immunohistochemical staining for T. pallidum showed innumerable organisms in 2 of the cases. Pathologists must be aware of the possibility of syphilis causing hepatic inflammatory masses in human immunodeficiency virus–positive men who have sex with men in order to avoid misdiagnosis or delayed treatment.

Evaluation of radiofrequency ablation using the 1-Fr wire electrode in the porcine pancreas, liver, gallbladder, spleen, kidney, stomach, and lymph nodes: A pilot study.

The frequency of detecting asymptomatic incidental lesions of the pancreas is increasing. A substantial number of these lesions are either malignant or premalignant, thus mandating pancreatic resection. A less invasive treatment option may be feasible for selected patients. Endoscopic ultrasound‐guided radiofrequency ablation (RFA) may be offered as a treatment option for these patients. The objective of the present study was to evaluate the performance characteristics of monopolar RFA using a 1‐Fr wire electrode in porcine pancreas, liver, gallbladder, spleen, kidney, stomach, and lymph nodes.

Colitis promotes neuronal differentiation of Sox2+ and PLP1+ enteric cells

Mechanisms mediating adult enteric neurogenesis are largely unknown. Using inflammation-associated neurogenesis models and a transgenic approach, we aimed to understand the cell-source for new neurons in infectious and inflammatory colitis. Dextran sodium sulfate (DSS) and Citrobacter rodentium colitis (CC) was induced in adult mice and colonic neurons were quantified. Sox2GFP and PLP1GFP mice confirmed the cell-type specificity of these markers. Sox2CreER:YFP and PLP1creER:tdT mice were used to determine the fate of these cells after colitis. Sox2 expression was investigated in colonic neurons of human patients with Clostridium difficile or ulcerative colitis. Both DSS and CC led to increased colonic neurons. Following colitis in adult Sox2CreER:YFP mice, YFP initially expressed predominantly by glia becomes expressed by neurons following colitis, without observable DNA replication. Similarly in PLP1CreER:tdT mice, PLP1 cells that co-express S100b but not RET also give rise to neurons following colitis. In human colitis, Sox2-expressing neurons increase from 1–2% to an average 14% in colitis. The new neurons predominantly express calretinin, thus appear to be excitatory. These results suggest that colitis promotes rapid enteric neurogenesis in adult mice and humans through differentiation of Sox2- and PLP1-expressing cells, which represent enteric glia and/or neural progenitors. Further defining neurogenesis will improve understanding and treatment of injury-associated intestinal motility/sensory disorders.

Prevalence of oesophageal epidermoid metaplasia in 1048 consecutive patients and 58 patients with squamous neoplasms.

Oesophageal epidermoid metaplasia is defined by a dense granular layer with overlying hyperorthokeratosis, resembling the epidermis of skin. A possible association between epidermoid metaplasia, squamous dysplasia and squamous cell carcinoma has been proposed. The aim of this study was to compare the prevalence of epidermoid metaplasia in patients with oesophageal squamous neoplasms with that in a control cohort.