Neoadjuvant (preoperative) chemoradiotherapy of advanced rectal tumors / Elorehaladott végbéldaganatok neoadjuváns (preoperatív) kemoradioterápiája

Introduction: There have been significant changes in the treatment protocol for rectal tumors in recent decades, greatly reducing the rate of local recurrence and distant metastasis, thereby increasing overall survival. Method: We performed a retrospective processing and statistical analysis of the data of 362 patients with rectal cancer who underwent local neoadjuvant chemoradiotherapy and then underwent surgical treatment between 1 January 2010 and 31 December 2017 at the Institute of Surgery of the University of Debrecen. We compared the response rate and overall survival results of our patients with local neoadjuvant treatment to the outcomes of total neoadjuvant treatment reported by the recent large international studies. Results: We experienced complete pathological regression in 8.6% of our patients. After neoadjuvant therapy, 10.7% of our patients experienced distant metastasis at the time of the operation or within 3 months period thereafter. In our study, the rate of response to the neoadjuvant treatment was a prognostic factor independent of the stage at di-agnosis and recognition. The groups with better response produced significantly better survival results. Conclusion: The total neoadjuvant treatment doubled the number of patients with complete pathological response, and the incidence of distant metastasis was by 7% lower in both recent international studies compared to the local neoadjuvant group. 85% of our patients were T3-4N+ stage at the time of recognition. Given the 10.7% rate of dis- tant metastases detected at the time of surgery or within 3 months in our patient population, we can state that ap- proximately half of our patients would have benefited from the administration of total neoadjuvant therapy which produced better outcomes. Based on this conclusion, we decided to introduce the total neoadjuvant therapy protocol in our department for treatment of patients with advanced rectal tumors.

T-cell Receptor Is a Threshold Detector: Sub- and Supra-Threshold Stochastic Resonance in TCR-MHC Clusters on the Cell Surface.

Stochastic resonance in clusters of major histocompatibility molecules is extended by a more detailed description of adaptive thresholding and by applying the notion of suprathreshold stochastic resonance as a stochastically quantizing encoder of transmembrane signaling downstream of major histocompatibility molecules and T-cell receptors on the side of presenting and recognizing cells, respectively. The adaptive nature of thresholding is partly explained by a mirroring of the noncognate-cognate dichotomy shown by the T-cell receptor structure and the kinetic-segregation model of the onset of T-cell receptor triggering. Membrane clusters of major histocompatibility molecules and T-cell receptors on their host cells are envisioned as places of the temporal encoding of downstream signals via the suprathreshold stochastic resonance process. The ways of optimization of molecular prostheses, such as chimeric antigen receptors against cancer in transmembrane signaling, are suggested in the framework of suprathreshold stochastic resonance. The analogy between Förster resonance energy transfer and suprathreshold stochastic resonance for information transfer is also discussed. The overlap integral for energy transfer parallels the mutual information transferred by suprathreshold stochastic resonance.

Quadruplicate Synchronous Adenocarcinoma of the Colon with Distant Metastases-Long-Term Molecular Follow-Up by KRAS and TP53 Mutational Profiling.

Anatomically independent tumor foci represent biologically distinct neoplasias, potentially featured by different progressivity and treatment responsiveness. To demonstrate the biological complexity, a metastatic colon adenocarcinoma patient originally presenting with four independent primary tumors of the right colon half and altogether eight distant metastases was followed by molecular testing. Next-generation sequencing results highlighted the mutational profile of the individual primaries and the dynamics of the different gene variants observed during follow-up. The four primary colon tumors presented with four different KRAS genotypes, one of them with a wild-type and three with pathogenic variants, without overlap. These were the following: c.35G > A; p.Gly12Asp with 40.6% variant allele frequency (VAF); c.34G > T; p.Gly12Cys with 16.2% VAF and c.35G > T; p.Gly12Val with 15.1% VAF. In metastatic tumors, with one exception where no mutation was detected, only the KRAS c.34G > T; p.Gly12Cys mutation could be detected. TP53 gene variants were variable in the primary tumors, with a single dominant variant evolving in the follow-up metastases (c.820G > T; p.Val274Phe). Genetic profiling of individually developing synchronous malignancies uncovers the clonal relations of metastatic tumors. NGS gene panels provide a solution to follow the dynamics of key oncogene variants during the course of the disease and greatly contribute to therapy optimization.

Correction: Identification of Novel Pathogenic Sequence Variants of the Mismatch Repair Genes During Screening for Lynch Syndrome in a Single Centre of Eastern Hungary.

The original version of this article unfortunately contained a mistake. The variants listed in Table 3 of the original version of this article are not in line with the latest HGVS (Human Genome Variation Society) nomenclature (version 19.01).

Identification of Novel Pathogenic Sequence Variants of the Mismatch Repair Genes During Screening for Lynch Syndrome in a Single Centre of Eastern Hungary.

INTRODUCTION: Lynch syndrome is an autosomal dominant disorder, most frequent leading to colon cancer. Identification of patients with Lynch syndrome and screening of their family members are available prevention approach that can significantly decrease mortality. Unfortunately, routine screening still does not belong to standard of care in Hungary. In this study, we performed a comprehensive screening in order to identify patients with mismatch repair (MMR) mutation between the years of 2011 and 2014. Identified mutations were compared with those already published in the international databases. PATIENTS AND METHODS: Patients who underwent treatment for colorectal cancer at the Surgical Institute of the University of Debrecen were screened using the modified Amsterdam and Bethesda Criteria. Immunohistochemistry and microsatellite analyses were performed in order to identify possible mutation carrier cases. Suspicious cases underwent DNA sequencing to detect mutations in the mismatch repair genes (hMLH1, hMSH2). RESULTS: All together 760 colorectal cancer patients were screened. A total of 28 patients were identified as possible MMR mutation carrier and underwent further genetic evaluation. Pathogenic sequence variants of the MMR gene were found in 5 patients. Hypermethylation of the promoter region of the hMLH1 gene was identified in 2 patients. Two out of the 5 pathogenic sequence variants of the MMR gene were first identified by our group while other 2 mutations were previously published as possible founder mutations. CONCLUSION: Identification of families with Lynch syndrome, while challenging because of variable phenotypes at diagnosis, is feasible with available molecular biological technologies and crucial to reduce mortality caused by this syndrome.

Adaptive threshold-stochastic resonance (AT-SR) in MHC clusters on the cell surface.

Highly conserved 2D receptor clusters (membrane rafts) of immunological signaling molecules with MHCI and MHCII antigens as their cores have been observed in the past on the surface of T- and B-cell lines of lymphoid origin, as well as on cells from patients with colon tumor and Crohn's disease. Conservativity is related to the ever presence of MHCI molecules. Although they are suspected to play a role in maintaining these clusters and facilitating transmembrane signaling, their exact role has been left largely enigmatic. Here we are suggesting stochastic resonance (SR), or "noise-assisted signal detection", as a general organizing principle for transmembrane signaling events evoked by processes like immune recognition and cytokine binding taking place in these clusters. In the conceptual framework of SR, in immune recognition as a prototype of transmembrane signaling, the sea of self-peptide-MHC complexes around a nonself-peptide presenting MHC is conceived as a source of quickly fluctuating unspecific signal ("athermal noise") serving the extra energy for amplifying the weak sub-threshold specific signal of the nonself-peptide presenting MHC. This same noise is also utilized for a readjustment of the threshold - and also the sensitivity and specificity - of detection by a closed loop feedback control of the TcR-CD8 (CD4) proximity on the detecting T-cell. The weak sub threshold specific signal of nonself-peptide presenting MHC is amplified by the superposing unspecific signals of the neighboring self peptide-MHC complexes towards the T-cell receptor as the detector. Because in a successful detection event both self- and nonself-peptides are detected simultaneously, the principle of coincidence (or lock-in) detection is also realized. The ever presence of MHC islands gets a natural explanation as a source of extra power - in a form of "athermal noise" - needed for coincidence detection and frequency encoding the evoked downstream signals. The effect is quite general, because the actual type of molecules surrounding a chief signaling molecule - like nonself-peptide holding MHC, interleukin-2 and -15 cytokine receptors (IL-2R/15R) - as the fluctuating interaction energy sources is immaterial. The model applies also for other types of signaling, such as those evoked by cytokine binding. The phenomenon of SR can also be interpreted as sampling of a low frequency, specific signal with a high frequency unspecific signal, the "noise". Recipes for identifying other forms of SR in membrane clusters with biophysical tools are recommended.

[Open transgastric necrosectomy for extended walled-off pancreas necrosis]. / Kiterjedt, demarkált pancreas necrosis sebészi kezelése transgastricus necrectomiával.

AIMS: In severe acute pancreatitis the timing of necrosectomy is ideally should be postponed 4-6 weeks after the onset of the disease when the walled-of pancreatic necrosis (WOPN) has developed. The authors present their experience with open transgastric necrosectomy for extended WOPN. PATIENTS AND METHODS: The authors performed 17 (12 male, 5 female with a mean age of 61.6 ± 15.1 years) open transgastric necrosectomies for extended WOPN in a period of 1, January 2012 and 31, December 2017. Before the operations conservative and semiconservative therapy was used for an average of 74.6 ± 83.1 days. The mean size of the WOPNs was 13.8 ± 5.2 cm with localisation of the retrocolic and retroduodenal regions. All necroses were septic. RESULTS: Complications related to the operation were not observed. The mean time of hospitalization after the surgery was 11.6 ± 12.8 days. The mortality rate was 5.9%. Late operation or other interventions for pseudocyst or pancreas fistula formation was not performed. Two patients needed endoscopic dilatation with lavage in the early postoperative period because of fever. New diabetes mellitus was not observed but worsening of previously existed diabetes developed in 6.3% of the cases. CONCLUSIONS: The open transgastric necrosectomy is safe and effective for extended WOPN. The advantage of this type of necrosectomy is the prevention of pancreatic pseudocyst and fistula formation.

Hydatid disease of pancreas: A case report.

Primary pancreatic hydatid disease is extremely rare. Diagnosis of the disease is difficult because hydatid cysts can be confused with a pseudocyst or neoplastic cystic diseases. Authors report a case of a surgically treated hydatid disease of the uncinate process of pancreas. In a 34-year-old patient with minor symptoms, a cystic disease of the pancreas was accidentally identified. CT scan revealed a multivesicular cystic mass with a maximum of 13-cm diameter and with a calcificated wall. During laparotomy, the uncinate process of pancreas was resecated and the cystic lesion was enucleated. Patient was recovered without complications and recurrence of the disease. There must be a suspicion of hydatid disease when cysts are identified in good conditioned, asymptomatic patients, or in case of wall calcification or multivesicular cysts revealed by radiological images. Surgical procedures are recommended in uncertain diagnoses too, because differentiation preoperatively between cystic pancreatic lesions is often impossible.

Confocal microscopic dual-laser dual-polarization FRET (2polFRET) at the acceptor side for correlating rotations at different distances on the cell surface.

Relationship of donor and acceptor fluorescence anisotropies as well as efficiency of fluorescence resonance energy transfer (FRET) has been investigated in a confocal microscope in the context of FRET systems comprised of donor and acceptor-labeled MHCI and MHCII receptors on the surface of Kit-225 K6 human T-cells. The measurements have been carried out in a 2-laser, 5-signal platform where the total donor fluorescence intensity and 2 acceptor fluorescence intensities with their anisotropies - one at the donor's excitation wavelength, the other at the acceptor's excitation wavelength - have been detected. This configuration enabled the determination of FRET efficiency and correlating it with the two acceptor fluorescence anisotropies as a kind of calibration. Estimations for the FRET-enhanced donor fluorescence anisotropy, the directly excited acceptor fluorescence anisotropy, and the fluorescence anisotropy of sensitized emission have been obtained. Procedures for determining FRET by measuring only the total donor intensity and the acceptor intensity and its anisotropy, or two acceptor intensities and their anisotropies have been elaborated, the errors of which have been estimated based on the fluorescence anisotropy values obtained in the calibration with the method of flow cytometric energy transfer (FCET). The combined detection of the donor and acceptor fluorescence anisotropies enabled also the determination of the lower and upper limits of the orientation factor for FRET (κ2). An increase in range for κ2 with increasing FRET efficiency has been observed, with average κ2 values different from the dynamic random average of 2/3. These observations call for the need of κ2 determination in proximity measurements, where the donor and acceptor orientations are not predictable. An increasing range of κ2 with increasing intermolecular proximity of the MHCI and MHCII receptors has been observed. This indicates that molecular flexibility in the clusters of the MHCI and MHCII receptors reduces with increasing cluster density, i.e. a "fluidity gradient" exists in the clusters. More specifically, the local density dependent flexibility can also be taken as a direct proof for that the association of these receptors is non-random, but mediated by some type of physical interaction, a finding as a benefit of FRET detection by polarization spectroscopy. Two new quantities - the quenched donor fluorescence anisotropy and a fluorescence anisotropy analogue, the "dissymmetry index" of the polarized FRET efficiency components - have also been introduced for the characterization of the orientational dynamics of the excited state during FRET.

[Significance of the monitoring and screening for hereditary nonpolyposis colorectal carcinoma syndrome patients by presenting a case of a family tree]. / A hereditaer nonpolyposus colorectalis carcinoma szindrómás betegek szurésének és szoros utánkövetésének fontossága egy családfa bemutatása kapcsán.

INTRODUCTION: Hereditary nonpolyposis colorectal carcinoma (HNPCC) is an autosomal dominant disease, which shows familial clustering. AIM: We would like to emphasize the importance of monitoring the HNPCC syndrome patients by presenting a case of a proven MMR gene mutation carrier and her family tree encompassing 10 years. MATERIALS AND METHOD: To screen a suspected HNPCC Hungarian family member we are taking thorough family histories. If the diagnosis of HNPCC was further supported by immunohistology and the microsatellite status, sequencing of the MMR genes was carried out. RESULTS: A novel mutation in exon 6 of the hMSH2 gene leading to the deletion of two nucleotide pairs [c.969-970delTC] was detected in our patient. During the 10-year follow-up period of our patient new HNPCC-associated tumors have developed in several family members. Conslusion: Close surveillance of the patient and its family members at risk was effective, although it requires compliance from the subjects. Orv Hetil. 2017; 158(30): 1182-1187.

[Significance of the computed tomography assisted morphometry in the surgical planning of eventrated abdominal wall hernias]. / A komputertomográfia jelentosége az eventerált, óriás hasfali sérvek mutéteinek tervezésében.

INTRODUCTION: The eventrated, giant abdominal wall hernias represent a considerable challenge in our practice. Presently, preoperative evaluation of the musculo-aponeurotic elements of the abdominal wall by CT imaging is not part of routine planning of surgery. AIM: Evaluation of the abdominal wall hernia progression in time. Moreover, follow up the changes of the abdominal wall structures following series of intraabdominal surgeries. METHOD: Abdominal CT imaging were performed on the 1st, 3rd, 6th, 12th, 18th, and 24th postoperative months after the primary series of surgeries in the cases of 12 patients, whose reconstructive surgeries were not possible. A prospective data collection was applied. Changing of the bilateral rectus muscle morphology, the evolution in time of the midline gap, and the progressive dynamism of the midline wall defects were determined. RESULTS: A characteristic and progressive midline defect enlargement could be settled. Data analysis yielded that the combined width of the bilateral rectus muscles is sufficient to cover the midline abdominal wall defect, although there is an "optimal" timeframe for performing the intervention. CONCLUSION: CT evaluation of abdominal wall prior to reconstructive surgeries of loss of abdominal wall domain has a strong significance on determining and designing the adequate surgical procedure. Orv. Hetil., 2017, 158(7), 257-263.

Incarcerated and eventrated abdominal wall hernia reconstruction with autologous double-layer dermal graft in the field of purulent peritonitis-A case report.

INTRODUCTION: Double-layer dermal grafts are used for the management of complicated abdominal wall hernias in obese, high risk patients. The method has not yet been used in case of emergency in septic/dirty environment. CASE REPORT: A 76-year old female patient (BMI 36.7kg/m2) was admitted with mechanical bowel obstruction and sepsis caused by a third time recurred, incarcerated and eventrated abdominal wall hernia. During the emergency surgery perforation of the terminal ileum and the ascending colon was detected, along with a feculent peritonitis and extended abdominal wall necrosis. Extended right hemicolectomy and necrectomy of the abdominal wall were performed. The surgery resulted in an abdominal wall defect measuring 223cm2, for the management of which direct closure was not possible. Using a specific method, an autologous dermal graft was prepared from the redundant skin. The first dermal graft was placed under the abdominal wall with 5cm overlap, and the second layer was placed onto the first layer with 3cm overlap in a perforated fashion. The operating time was 250min. No significant intra-abdominal pressure elevation was measured. No reoperation was performed. On the fifth postoperative day, the patient was mobilised. She was discharged in satisfactory general condition on the 18th postoperative day. There is no recurrent hernia 8 months after the surgery. DISCUSSION: Abdominal wall reconstruction was possible in a necrotic, purulent environment by using a de-epithelised autologous double layer dermal graft, without synthetic or biological graft implantation. The advantage of the procedure was cost-effectivity, and the disadvantage was that only in an obese patient is the sufficient quantity of dermal graft available. CONCLUSION: A homogeneous internal and perforated outer dermal graft was suitable for bridging the abdominal gap in the case of an obese, high risk patient. Autologous dermal grafts can be a safe and feasible alternative to biological meshes in emergency abdominal wall surgeries. Evaluation of a case series can be the next cornerstone of the method described above.

Primary angiosarcoma of the pancreas mimicking severe acute pancreatitis--case report.

Primary angiosarcoma of the pancreas is an extremely rare neoplasm that often mimicks severe acute pancreatitis. A 58-year-old man was admitted with clinical and laboratory signs of severe acute pancreatitis. Contrast enhanced CT scan demonstrated haemorrhagic necrotizing inflammation of the pancreas involving the pancreatic tail, splenic hilum and small bowels with multiple peripancreatic and free abdominal fluid collection. Percutaneous drainage was performed. After 13 days, laparotomy was indicated because of persistent intra-abdominal bleeding, fever and a palpable, rapidly growing mass in the left upper quadrant of the abdomen. During the operation a necrotic, haemorrhagic mass was found in the pancreatic tail; a frozen section showed malignancy, although the tumour was unresectable. Despite all conservative and surgical therapeutic attempts, the patient died within four weeks after diagnosis. Final histology justified primary angiosarcoma of the pancreas. If a patient with signs of severe acute pancreatitis has fever without elevated PCT, the presence of a malignant tumour of the pancreas should be considered.

Intraoperative tissue identification using rapid evaporative ionization mass spectrometry.

Rapid evaporative ionization mass spectrometry (REIMS) is an emerging technique that allows near-real-time characterization of human tissue in vivo by analysis of the aerosol ("smoke") released during electrosurgical dissection. The coupling of REIMS technology with electrosurgery for tissue diagnostics is known as the intelligent knife (iKnife). This study aimed to validate the technique by applying it to the analysis of fresh human tissue samples ex vivo and to demonstrate the translation to real-time use in vivo in a surgical environment. A variety of tissue samples from 302 patients were analyzed in the laboratory, resulting in 1624 cancerous and 1309 noncancerous database entries. The technology was then transferred to the operating theater, where the device was coupled to existing electrosurgical equipment to collect data during a total of 81 resections. Mass spectrometric data were analyzed using multivariate statistical methods, including principal components analysis (PCA) and linear discriminant analysis (LDA), and a spectral identification algorithm using a similar approach was implemented. The REIMS approach differentiated accurately between distinct histological and histopathological tissue types, with malignant tissues yielding chemical characteristics specific to their histopathological subtypes. Tissue identification via intraoperative REIMS matched the postoperative histological diagnosis in 100% (all 81) of the cases studied. The mass spectra reflected lipidomic profiles that varied between distinct histological tumor types and also between primary and metastatic tumors. Thus, in addition to real-time diagnostic information, the spectra provided additional information on divergent tumor biochemistry that may have mechanistic importance in cancer.

Prospective, comparative study for the evaluation of lymph node involvement in gastric cancer: Maruyama computer program versus sentinel lymph node biopsy.

BACKGROUND: Stage-adapted surgery guarantees the best outcome for patients with gastric cancer. Successful identification of lymph node involvement may help to reduce the number of extended lymphadenectomies. Preoperative diagnostic tools have low sensitivity and specificity for determining lymph node involvement. Evaluation of sentinel lymph nodes (SLNs) intraoperatively has good results, while the accuracy of the Maruyama computer program (MCP) is controversial. METHODS: We investigated 40 patients by the Maruyama computer model and labeled lymph nodes with blue dye for SLN mapping. To compare the probability calculations by MCP and the results of SLN mapping, we had to define a cutoff level; we did this using receiver-operating characteristics analysis. Sentinel lymph nodes were examined in frozen sections intraoperatively and by standard hematoxylin and eosin staining postoperatively. RESULTS: A total of 795 lymph nodes were removed and examined. The Maruyama computer model had a sensitivity of 91.3 %, specificity of 64 %, and accuracy of 80 % by the best cutoff point. The false-negative rate was 8.7 %. The sensitivity of SLN mapping was 95.7 %, the false-negative rate was 4.3 %, and the specificity was 100 %. The accuracy of SLN mapping was 97.4 %. Only the sensitivity of MCP and SLN biopsy was proven equivalent. CONCLUSIONS: Our results suggest that intraoperative SLN examination is superior to preoperative estimation with the MCP. Correct definition of lymph node involvement helps in planning the best stage-adapted surgery in gastric cancer.

[Comparison of wound infection rates after colon and rectal surgeries using triclosan-coated or bare sutures -- a multi-center, randomized clinical study]. / Sebfertozések gyakoriságának összehasonlítása colon- és rectummutétek után triclosan bevonatú varróanyag (PDS plus®) és azonos alapanyagú nem bevont varróanyag (PDS II®) felhasználása esetén - multicentrikus, randomizált, klinikai tanulmány.

BACKGROUND: Surgical Site Infection (SSI) is the third most frequent nosocomial infection, and accounts for 14-16% of all infections. While the treatment of SSI can be very costly, previous results indicated that triclosan may reduce SSI rate. Therefore, we carried out a prospective randomised trial to further evaluate the effect of triclosan after elective colorectal surgery. METHODS: Seven surgical units in Hungary were involved in a prospective, randomised, multicentric clinical trial to compare triclosan coated (PDS plus®) and uncoated (PDS II®) sutures for abdominal wall closure in elective colorectal surgery. Pre- and perioperative variables were recorded in an online database. The primary aims of the study were to determine the incidence of SSI and the pathogens associated with it, as well as evaluation of additional cost of treatment. RESULTS: 485 patients were randomised. SSI occurred in 47 cases (12.5%), of those 23 (12.23%) from the triclosan group (n = 188) and 24 (12.18%) from the uncoated group (n = 197, p = 0.982). In 13 (27.66%) cases late appearance of SSI was detected, of those 4 patients with triclosan coated suture (8.51%) and 9 patients with uncoated suture (19.15%, p = 0.041). There was no difference between the type of incisions or elective colon and rectal resections in terms of incidence of SSI. CONCLUSION: Beneficial effect of triclosan against Gram positive bacteria could not be confirmed in our study due to the relatively low number of patients with SSI. Furthermore, triclosan did not influence the incidence of SSI due to Gram negative bacteria. SSI rate decreased by 50% compared to our previous study, however, it was regardless of the use of coated or uncoated PDS loop. Finally, operative factors were more important than patient's risk factors in terms of incidence of SSI. In case SSI developed, delayed discharge from hospital as well as special wound care significantly increased overall cost of treatment.

Role of core needle biopsy in the treatment of radial scar.

Invasive tumor or ductal carcinoma in situ occur in radial sclerosing lesions in one third of the cases therefore, surgical excision is mandatory. Forty-five patients with radial scar morphology were examined. Ultrasound guided fine-needle aspiration biopsy (FNAB) and core biopsy (CB) were performed in all cases. The postoperative pathological findings were compared to the results of preoperative biopsies. Sensitivity of preoperative percutaneous biopsies (FNAB and CB) was 17.6% and 70.6%, false-negative rate was 82.4% with FNAB and 29.4% with CB. The negative predictive value was 48.1% and 84.8% respectively. Had we done preoperative cytology only, we would have had to perform a two-step procedure (sentinel lymph node biopsy) in 7 patients (15.6%), while with preoperative core biopsy it has decreased to 2 patients (4.4%). Preoperative CB in small radial stellate lesions is recommended to achieve accurate diagnosis in order to avoid a two-step surgical procedures.

Q48P mutation in the hMLH1 gene associated with Lynch syndrome in three Hungarian families.

Lynch syndrome (Hereditary nonpolyposis colorectal cancer, HNPCC) is an inherited disease with variable phenotype causing the development of colon cancer and other malignancies. The basis of the disease is believed to be the mismatch repair gene mutations. Genetic screening has been performed among the patients who have undergone surgery for colon cancer at the University of Debrecen, Department of Surgery. Tumor samples of the screened patients were submitted to immunohistochemistry on hMLH1, hMSH2 and hMSH6 genes, microsatellite instability testing, followed by sequencing and multiple ligation dependent probe amplification. Three families were identified with the missense mutation c.143A>C (p.Q48P) of hMLH1 gene. In one of the families a segregation analysis of this particular variant was also accomplished. The segregation analysis revealed a clear correlation between the tumor cases and the occurrence of this mutation. However, none of the analyzed 100 healthy controls demonstrated the same aberration. There is only one published evidence in the literature about the presence of this rare variant in any population. The Gln to Pro switch in the ATPase domain, a conservative region of the hMLH1 gene, creates significant changes in the protein structure. These results indicate that this mutation is the abnormality responsible for the patients' phenotype and it is feasible that this particular aberration occurs more frequently among Hungarian Lynch syndrome patients.