Multifocal sporadic gastrointestinal stromal tumours (GISTs) may be misinterpreted as recurrent or metastatic disease, leading to inappropriate treatment. As molecular analysis is generally not ...available in routine practise, histological criteria that would facilitate diagnosis of multiple primary GISTs in routine slides are needed. We studied 14 GISTs (mean size, 2.7 cm) from six men and one woman (mean age, 70 years) applying morphological features and direct sequencing of
KIT
,
PDGFRA
,
BRAF
, and
KRAS
. Diagnosis was synchronous in five and metachronous in two patients. Paired tumours originated in stomach/small bowel (
n
= 5), duodenum/jejunum (
n
= 1), and stomach/oesophagus (
n
= 1) and revealed spindle (
n
= 10) and mixed spindle and epithelioid (
n
= 4) phenotype. Tumours were well circumscribed and have involved the muscularis propria in a pattern typical of primary GISTs. Different somatic
KIT
mutations were found in tumours from four patients. One patient had a
KIT
-mutated and a
BRAF
-mutated (V600E) tumour. Two patients had wild-type tumours. No
PDGFRA
or
KRAS
mutations were detected. Our results underscore the molecular heterogeneity of sporadic multifocal GISTs. The characteristic involvement of the muscularis propria and the site-typical morphology and immunophenotype facilitated the diagnosis of primary GISTs in all cases and correlated with molecular findings, emphasising the value of conventional histology in recognising independent primary GISTs.
Aims: Lymph node (LN) stage is still the strongest prognostic marker in potentially curable gastric cancer. Accuracy of histopathological lymph node assessment depends on the number of investigated ...LNs and detection rate of metastases and micrometastases. The aim was to perform a feasibility study employing intra‐arterial methylene blue injection – a novel method to improve LN harvest – and ex vivo sentinel LN mapping.
Methods and results: A total of 33 cases were enrolled, including 14 retrospective cases that served as a control group. The methylene group showed a highly significant improved mean LN harvest compared with unstained cases, with 38 ± 14 versus 21 ± 10 LNs (P < 0.001), respectively. The detection rate of ex vivo sentinel mapping was 88%. No skip metastases occurred.
Conclusion: Both techniques have the potential to improve the accuracy of histopathological LN staging and can be combined successfully.
The detection of tumor cells in the sentinel lymph node (SLN) is of great importance for the prognosis of cancer patients. At present, immunohistochemistry and RT-PCR for tumor marker expression are ...the most sensitive techniques available for this analysis. However, so far, most RT-PCR-based analyses of SLNs have been performed on fresh material, excluding a direct comparison with the (immuno)histologic results. In our view, this does not entirely aid routine diagnosis. We established an efficient method for RNA extraction and RT-PCR from paraffin sections of SLNs from prostate cancer patients and compared the results with the (immuno)histologic data of adjacent sections. Amplifiable RNA was obtained from 133 SLNs of 68 prostate cancer patients. Correlation of PSA-specific RT-PCR with (immuno)histologic findings showed a positive and negative predictive value of 83% and 100%, respectively, for the prostate cancer patients investigated. Four of 12 patients with biochemical relapse, but without (immuno)histologically detectable tumor cells were RT-PCR-positive for PSA. We found that single sections of paraffin-embedded SLNs are suitable for routinely performed RT-PCR. Combined with (immuno)histology, PSA-specific RT-PCR is a revealing supplementary technique for the detection of tumor cells in SLNs of prostate cancer patients.
