M. Priyanthi Kumarasinghe

Pointers and pitfalls of mycophenolate-associated colitis

Aims Mycophenolate-associated colitis has been previously reported to show patterns of colonic mucosal injury mimicking a host of conditions, including graft-versus-host disease, ischaemia and inflammatory bowel disease (IBD). The aim of this study is to characterise, semiquantitatively, pathological changes of mycophenolate mofetil (MMF) mucosal injury. Methods Seven transplant patients receiving MMF who underwent colonoscopic examination and biopsy were identified retrospectively over a 2-year period. Multiple histologic parameters, including architectural distortion, cryptitis, stromal active inflammation, individual damaged crypts (IDC) and crypt apoptotic figures were evaluated in the biopsies semiquantitatively. Where biopsy site was identified, the parameters were assessed separately in biopsies from right and left colon. Results All cases showed mixed patterns of mucosal injury. All seven cases showed focal architectural distortion (in 58% of fragments per case), focal cryptitis (mean 3.0 foci per case), increased crypt apoptosis (mean 26.5/100 crypts) and IDC (mean 3.0 foci). Focal changes resembling acute self-limited colitis were noted in three cases. Possible proximal accentuation of some changes was noted with right side biopsies tending to show greater crypt apoptotic activity and more foci of architectural distortion. Three cases showed dual pathology (two with cytomegalovirus (CMV) infection and one with IBD). Conclusions Although a wide spectrum of changes may be seen in MMF-associated colitis, important microscopic clues include a mixed pattern of injury (typically a combination of crypt apoptosis, isolated crypt damage and architectural distortion), and possible proximal accentuation of pathologic changes. The need for clinical correlation and follow-up is emphasised by the occurrence of dual pathology in patients treated with MMF.

More than just counting eosinophils: proximal oesophageal involvement and subepithelial sclerosis are major diagnostic criteria for eosinophilic oesophagitis

Background According to American Gastroenterological Association Institute criteria, the diagnosis of eosinophilic oesophagitis (EOE) requires clinicopathological correlation. In the appropriate clinical context, a high eosinophil count (HEC, defined as ≥15/HPF) is considered pathological evidence of EOE. However, HEC may not always be identified in biopsies given its patchy distribution, and there may be histological overlap between EOE and gastro-oesophageal reflux disease (GORD) in the distal oesophagus. Aims To evaluate the utility of subepithelial sclerosis and HEC in proximal oesophageal biopsies as additional diagnostic criteria. Methods Cases between 2004 and 2008 with paired proximal and distal oesophageal biopsies and the mention of eosinophils in the reports were retrieved from PathWest Queen Elizabeth II Medical Centre archives. Biopsies were reviewed and assessed for eosinophilic count and presence of subepithelial stroma and sclerosis. A final diagnosis was made after review of both biopsy and clinical details. Results There were 23 cases of EOE and 20 cases of GORD in an adult cohort. In comparison to GORD, cases of EOE had significantly higher eosinophil counts in proximal (39.4 vs 0.6 eosinophils/HPF) and distal biopsies (35.6 vs 1.9), with HEC in proximal biopsies a feature exclusive to EOE (83% vs 0%). Subepithelial sclerosis was identified in at least one biopsy in 74% of EOE and in only a single case of GORD. Conclusions HEC in proximal oesophageal biopsies and subepithelial sclerosis should be considered major diagnostic findings in EOE.

Optimizing the multimodal approach to pancreatic cyst fluid diagnosis developing a volume-based triage protocol

The objective of this study was to develop a triage algorithm to optimize diagnostic yield from cytology, carcinoembryonic antigen (CEA), and v‐Ki‐ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) testing on different components of a single pancreatic cyst fluid specimen. The authors also sought to determine whether cell block supernatant was suitable for CEA and KRAS testing.

HER2 testing in malignant effusions of metastatic gastric carcinoma: Is it feasible?

HER2 testing on effusions of metastatic gastric carcinoma may provide a valuable alternative to testing on primary biopsies. This study assessed the feasibility of this method by immunohistochemistry (IHC) and silver in situ hybridization (SISH). Cell blocks from 46 effusions from metastatic gastric carcinoma were examined. IHC was scored using the modified criteria of Hofmann et al. An average of ≥6 signals per nucleus was considered amplification on SISH. Results were compared with histological specimens to assess HER2 status concordance. Cell blocks showed a poorly cohesive pattern in 30 (65%), aggregates in 7 (15%), and mixed pattern in 9 (20%). Seven (15%) showed an IHC 2+/3+ reaction with a membranous pattern, appearing more granular than in histology. Three (7%) showed HER2 amplification on SISH. In 18 cases (39%), HER2 status was compared with histological specimens, showing 100% concordance. Difficulties were encountered in distinguishing malignant cells from reactive mesothelial cells in 12 (26%). This study supports the feasibility of HER2 assessment on effusions. The incidence of HER2 positivity (7% with SISH+ and IHC 2+/3+) was lower than reported in histological samples. Further refinement and validation will enhance the use of this method in clinical practice and overcome difficulties encountered. Diagn. Cytopathol. 2015;43:80–85.

BRAF p.Val600Glu (V600E) mutation detection in thyroid fine needle aspiration cell block samples: a feasibility study

Summary Assessing BRAF mutation status in thyroid fine needle aspiration (FNA) cytology samples by both immunohistochemistry (IHC) and molecular methods has been documented in recent literature. We aim to highlight issues relating to quality and quantity of cellular material and DNA extracted from cell block samples. BRAF mutation status was assessed by both molecular and IHC methods in cell block material from thyroid FNA samples over a range of diagnostic categories, and correlated with available follow-up resection specimens. Of 39 samples there were 14 cases with ‘inconclusive’ cytology (Bethesda diagnostic categories 3, 4 or 5) and 25 cases with malignant cytology. Follow-up information was available in 38 of 39 cases and resection material for comparison in 18 of 39 case. Detection of BRAF mutation in cell block samples by combined molecular and IHC methods showed 100% specificity and 71.4% sensitivity compared to subsequent histologically confirmed BRAF mutated papillary thyroid carcinoma. IHC detected BRAF mutation in two (8.2%) cases which were negative by molecular methods and confirmed mutation positive by IHC and molecular methods on subsequent histology. Low extracted DNA concentration did not appear to preclude detection of BRAF mutation, although cell blocks with lower tumour cell content were over-represented in cases that were wild-type on FNA material and BRAF mutant on subsequent histology. BRAF mutation detection in cell block material is feasible and highly specific for papillary thyroid carcinoma. Best results are obtained by a combination of molecular and IHC methods.

Concordance of HER2 expression in paired primary and metastatic sites of gastric and gastro-oesophageal junction cancers

Summary HER2 is amplified/overexpressed in a subset of gastric and gastro-oesophageal junction cancers. Addition of anti-HER2 therapy has been shown to provide survival benefit in this setting. However, there are limited data assessing the concordance of HER2 status between primary and metastatic sites. A total of 113 samples from 43 paired primary and metastatic tumours were tested for HER2 status, by immunohistochemistry (IHC) for protein expression and silver in situ hybridisation (SISH) for gene amplification. Primary sites tested included endoscopic biopsies (n = 30) and resections (n = 24). Metastatic samples included lymph nodes (n = 29), peritoneal effusions (n = 21) and miscellaneous sites (n = 9). The overall HER2+ rate was 11%. Of 41 (95%; 95% CI 88.5–100%) concordant cases, 38 were HER2– and three were HER2+. There were two (5%) discordant cases, one of which showed heterogeneity of HER2 expression. This series confirms a high concordance rate of 95%, supporting that testing of primary tumours and metastases is equally valid and providing clinical rationale for the addition of anti-HER2 therapy in HER2+ disseminated disease.

Macroscopic Assessment and Cut Up of Endoscopic Resection Specimens for Early Esophageal Glandular Malignancies

Pathological assessment of tissue is the gold standard for diagnosis and staging of neoplasia and provides key prognostic information for clinical management. Proper macroscopic assessment and cut-up technique is essential to ensure that the overall assessment is correct and reproducible. Endoscopic mucosal resection is a technique used for removing early neoplastic glandular lesions of the esophagus at the level of submucosa. Here, we describe the macroscopic assessment and dissection techniques used for the routine handling of endoscopic mucosal resection specimens in the clinical laboratory.

Processing of Surgical Specimen (Esophagogastrectomy) for Esophageal Adenocarcinoma

An esophagogastrectomy is a surgical procedure that is performed for treatment of confirmed localized esophageal and esophagogastric junction adenocarcinoma. Proper macroscopic assessment and cut-up technique is essential to ensure that the overall assessment is correct and reproducible. Here, we describe a standard for macroscopic assessment and dissection to be used for routine handling of esophagogastrectomy specimens in the clinical laboratory.