Paméla Baldin

A clinico‐pathologic study of placenta percreta

To review a single‐center case series of placenta percreta and to evaluate risk factors and the impact of surgical techniques used in previous cesarean delivery.

Evaluation of the correlation between KRAS mutated allele frequency and pathologist tumorous nuclei percentage assessment in colorectal cancer suggests a role for zygosity status

Evaluation of molecular tumour heterogeneity relies on the tumorous nuclei percentage (TNP) assessment by a pathologist, which has been criticised for being inaccurate and suffering from interobserver variability. Based on the ‘Big Bang theory’ which states that KRAS mutation in colorectal cancer is mostly homogeneous, we investigated this issue by performing a critical analysis of the correlation of the KRAS mutant allele fraction with the TNP in 99 colorectal tumour samples with a positive KRAS mutation status as determined by next-generation sequencing. Our results yield indirect evidence that the KRAS zygosity status influences the correlation between these parameters and we show that a well-trained pathologist is indeed capable of accurately assessing TNP. Our findings indicate that tumour zygosity, a feature which has largely been neglected until now, should be taken into account in future studies on (colorectal) molecular tumour heterogeneity.

Response to letter to the editor by Dr. Villanacci: toward optimal processing of endoscopic submucosal dissection specimens.

Dear Sir, We would like to thank Villanacci et al. for complementing our paper by further addressing important issues regarding lateral margin analysis in endoscopic submucosal dissection specimens. It was enlightening to read about their suggestion to use a fenestrated biocassette to avoid the use of potentially damaging pins to flatten specimens in macroscopic handling. We were also interested to learn about the lateral margin sectioning approach adopted at their institution, involving rotation and re-inclusion of lateral margins, which has similar aims to our technique. While the use of a biocassette is appealing, we believe it may not be ideal for the following reasons: The use of pins is mainly important to avoid notorious shrinkage artifacts of the muscularis mucosae during formalin fixation [1, 2]. The muscularis mucosae are histologically valuable for staging purposes, and it is important to ensure its integrity. In a biocassette, it seems that the tissue is still susceptible to horizontal shrinkage, especially for large lesions that may be difficult to spread out without the help of needles. Horizontal shrinkage therefore remains an issue with the biocassette, for large and small specimens alike. Along the same line, as the ESD technique becomes more common in hospitals across the globe, gained expertise will allow for the removal of larger and larger lesions, which in the colon have a tendency to be particularly large, especially the villous type [3, 4]. In our study, 57% of specimens had the largest dimension of 6.5 cm or more. In the image provided by Villanacci et al. biocassette appears to be 7 × 5 cm, which could accommodate only a part of our samples. Even if biocassettes are available in an 18 × 18 cm model, it would be technically difficult to manage these bulky items in the laboratory. The time it takes to work with them and the additional cost associated with large biocassettes may be more limiting than the disadvantages of the pinning technique. In addition, in our view, the statement that the Bbiocassette technique^ is superior to the Bpinning technique^ is not substantiated by solid data. Villanacci et al. state that the biocassette technique enables complete lateral margin examination in 86% of cases, while this is only the case for about 50% when using the pinning technique [5], but they do not explain which criteria they used to obtain these values. We are convinced that the pinning technique should remain the standard recommended technique. Only when studies using specific criteria convincingly show that the biocassette provides better information, one might consider adapting the existing guidelines. We should like to add that there are multiple ways to minimize pin-induced distortion of specimens when using this technique. One way is to adapt macroscopic sections to the location of pinholes. That is, both parallel and perpendicular sections during macroscopic handling can be preferentially made where the pins were located. With this approach, macroscopically altered zones are kept to a minimum. In addition, in their recommendation to use the pinning technique, the * Anne Jouret-Mourin anne.mourin@uclouvain.be

Diffuse pseudo-tumoral pericardial tuberculosis.

A 29-year-old immunocompetent woman presented with increasing dyspnoea for 1 month, fever of unknown origin and cough. The electrocardiogram was unremarkable. Laboratory tests showed mild inflammatory syndrome and anaemia. Transthoracic echocardiography demonstrated a hyperechogenic invasive intra pericardial mass invading the two atria with characteristics suggesting a …