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Pancreatic ductal adenocarcinoma (PDAC) is reported to be amongst the cancers with the lowest survival rate at 5 years. In the present study we aimed to validate a targeted next-generation sequencing (tNGS) panel to use in clinical routine, investigating genes important for PDAC diagnostic, prognostic and potential theragnostic aspect. In this NGS panel we also designed target regions to inquire about loss of heterozygosity (LOH) of chromosome 18 that has been described to be possibly linked to a worse disease progression. Copy number alteration has also been explored for a subset of genes. The last two methods are not commonly used for routine diagnostic with tNGS panels and we investigated their possible contribution to better characterize PDAC. A series of 140 formalin-fixed paraffin-embedded (FFPE) PDAC samples from 140 patients was characterized using this panel. Ninety-two % of patients showed alterations in at least one of the investigated genes (most frequent KRAS, TP53, SMAD4, CDKN2A and RNF43). Regarding LOH evaluation, we were able to detect chr18 LOH starting at 20% cell tumor percentage. The presence of LOH on chr18 is associated with a worse disease- and metastasis-free survival, in uni- and multivariate analyses. The present study validates the use of a tNGS panel for PDAC characterization, also evaluating chr18 LOH status for prognostic stratification.

Malignant pleural mesothelioma (MPM) is an aggressive cancer with limited therapeutic options. We evaluated the impact of CDK4/6 inhibition by palbociclib in 28 MPM cell lines including 19 patient‐derived ones, using various approaches including RNA‐sequencing. Palbociclib strongly and durably inhibited the proliferation of 23 cell lines, indicating a unique sensitivity of MPM to CDK4/6 inhibition. When observed, insensitivity to palbociclib was mostly explained by the lack of active T172‐phosphorylated CDK4. This was associated with high p16INK4A (CDKN2A) levels that accompany RB1 defects or inactivation, or (unexpectedly) CCNE1 overexpression in the presence of wild‐type RB1. Prolonged palbociclib treatment irreversibly inhibited proliferation despite re‐induction of cell cycle genes upon drug washout. A senescence‐associated secretory phenotype including various potentially immunogenic components was irreversibly induced. Phosphorylated CDK4 was detected in 80% of 47 MPMs indicating their sensitivity to CDK4/6 inhibitors. Its absence in some highly proliferative MPMs was linked to very high p16 (CDKN2A) expression, which was also observed in public datasets in tumours from short‐survival patients. Our study supports the evaluation of CDK4/6 inhibitors for MPM treatment, in monotherapy or combination therapy.

Background Pulmonary hypertension and right ventricular (RV) dysfunction are major prognostic determinants in patients with heart failure with preserved ejection fraction (HFpEF). The underlying pathomechanisms remain unknown. In this context, we sought to study the pathogenesis of pulmonary hypertension and RV dysfunction in a rat model of obesity‐associated HFpEF. Methods and Results HFpEF was induced in obesity‐prone rats fed a high‐fat diet (n=13) and compared with obesity‐resistant rats fed with standard chow (n=9). After 12 months, the animals underwent echocardiographic and hemodynamic evaluation followed by tissue sampling for pathobiological assessment. HFpEF rats presented mild RV pressure overload (with increased RV systolic pressure and pulmonary vascular resistance). No changes in pulmonary artery medial thickness and ex vivo vasoreactivity (to acetylcholine and endothelin‐1) were observed and RNA sequencing analysis failed to identify gene clustering in HFpEF lungs. However, released nitric oxide levels were decreased in HFpEF pulmonary artery, while lung expression of preproendothelin‐1 was increased. In HFpEF rats, RV structure and function were altered, with RV enlargement, decreased RV fractional area change and free wall longitudinal fractional shortening, together with altered right ventricle–pulmonary artery coupling (estimated by tricuspid annular plane systolic excursion/systolic pulmonary artery pressure). Hypertrophy and apoptosis (evaluated by transferase biotin‐ dUTP nick‐end labeling staining) were increased in right and left ventricles of HFpEF rats. There was an inverse correlation between tricuspid annular plane systolic excursion/systolic pulmonary artery pressure and RV apoptotic rate. Plasma levels of soluble suppression of tumorigenicity‐2, interleukin‐1β, ‐6 and ‐17A were increased in HFpEF rats. Conclusions Obesity‐associated HFpEF in rats spontaneously evolves to pulmonary hypertension–HFpEF associated with impaired right ventricle–pulmonary artery coupling that appears disproportionate to a slight increase in RV afterload.

Abstract Background With the increasing use of low dose CT scans, numerous pulmonary nodules are detected. As majority of them are benign, development of efficient non-surgical diagnostic intervention is mandatory. Electromagnetic navigation bronchoscopy (ENB) has been developed to reach difficult to access lesions. The aim of the present study was to compare the diagnostic yield of ENB procedures performed in a classical endoscopy suite or in a hybrid room equipped by a cone beam CT (CBCT). Methods A monocentric randomized study was performed in the Erasme Hospital between January 2020 and December 2021. Lung nodules of maximum 30 mm of diameter were eligible. In both arms (endoscopy or CBCT suites), ENB, fluoroscopic guidance and a radial endobronchial ultrasound were used to reach the lesion. Then six trans-bronchial biopsies (TBB) and one trans-bronchial lung cryobiopsy (TBLC) were performed. Primary outcomes were the diagnostic yield and diagnostic accuracy of the procedure. Results Forty-nine patients were randomized (24 in the endoscopy and 25 in the CBCT arms). The lesion size was 15,9 ± 4,6 mm and 16,6 ± 6,0 mm respectively (mean ± SD, p = NS). The diagnostic yield of ENB performed under CBCT guidance was 80% compared to 42% when performed in the endoscopy suite under standard fluoroscopic guidance (p

Abstract Introduction COVID-19-infected patients harbour neurological symptoms such as stroke and anosmia, leading to the hypothesis that there is direct invasion of the central nervous system (CNS) by SARS-CoV-2. Several studies have reported the neuropathological examination of brain samples from patients who died from COVID-19. However, there is still sparse evidence of virus replication in the human brain, suggesting that neurologic symptoms could be related to mechanisms other than CNS infection by the virus. Our objective was to provide an extensive review of the literature on the neuropathological findings of postmortem brain samples from patients who died from COVID-19 and to report our own experience with 18 postmortem brain samples. Material and methods We used microscopic examination, immunohistochemistry (using two different antibodies) and PCR-based techniques to describe the neuropathological findings and the presence of SARS-CoV-2 virus in postmortem brain samples. For comparison, similar techniques (IHC and PCR) were applied to the lung tissue samples for each patient from our cohort. The systematic literature review was conducted from the beginning of the pandemic in 2019 until June 1st, 2022. Results In our cohort, the most common neuropathological findings were perivascular haemosiderin-laden macrophages and hypoxic-ischaemic changes in neurons, which were found in all cases (n = 18). Only one brain tissue sample harboured SARS-CoV-2 viral spike and nucleocapsid protein expression, while all brain cases harboured SARS-CoV-2 RNA positivity by PCR. A colocalization immunohistochemistry study revealed that SARS-CoV-2 antigens could be located in brain perivascular macrophages. The literature review highlighted that the most frequent neuropathological findings were ischaemic and haemorrhagic lesions, including hypoxic/ischaemic alterations. However, few studies have confirmed the presence of SARS-CoV-2 antigens in brain tissue samples. Conclusion This study highlighted the lack of specific neuropathological alterations in COVID-19-infected patients. There is still no evidence of neurotropism for SARS-CoV-2 in our cohort or in the literature.

Abstract Clinical presentation as well as histological or biological findings can sometimes make the diagnosis of giant cell arteritis difficult. Histopathological features of temporal artery biopsy from giant cell arteritis patients are also challenging because of the various described appearances or even finding of clinically normal temporal artery biopsy does not rule out the diagnosis. We here describe the case of a 51‐year‐old man with temporal artery biopsy showing lymphocytes infiltrates in the adventitia corresponding to the so‐called adventitial pattern of giant cell arteritis according to Hernandez‐Rodriguez et al.

BackgroundChemerin is an extracellular protein with chemotactic activities and its expression is increased in various diseases such as metabolic syndrome and inflammatory conditions. Its role in lung pathology has not yet been extensively studied but both known pro- and anti-inflammatory properties have been observed. The aim of our study was to evaluate the involvement of the chemerin/ChemR23 system in the physiopathology of COVID-19 with a particular focus on its prognostic value.MethodsBlood samples from confirmed COVID-19 patients were collected at day 1, 5 and 14 from admission to Erasme Hospital (Brussels – Belgium). Chemerin concentrations and inflammatory biomarkers were analyzed in the plasma. Blood cells subtypes and their expression of ChemR23 were determined by flow cytometry. The expression of chemerin and ChemR23 was evaluated on lung tissue from autopsied COVID-19 patients by immunohistochemistry (IHC).Results21 healthy controls (HC) and 88 COVID-19 patients, including 40 in intensive care unit (ICU) were included. Plasma chemerin concentration were significantly higher in ICU patients than in HC at all time-points analyzed (p

Abstract Background The surgical lung biopsy (SLB) is the recommended sampling technique when the pathological analysis of the lung is required in the work-up of an interstitial lung disease (ILD) but trans-bronchial lung cryobiopsy (TBLC) is increasingly recognized as an alternative approach. As TBLCs have lower mortality and morbidity risks than SLB, this study aimed to investigate the safety of TBLCs in patients at higher risk of complications and for whom SLB was not considered as an alternative. Method This prospective study was conducted in two hospitals in which TBLCs were performed in patients with body mass index (BMI) > 35, and/or older than 75 years, and/or with severely impaired lung function (FVC 45 mmHg, and/or a clinically significant cardiac disease. Patients with any of these risk factors constituted the high-risk group. Clinical outcomes were compared with those obtained in patients without these risk factors (low-risk group). Results Ninety-six patients were included between April 2015 and April 2020, respectively 38 and 58 in the high-risk or the low-risk group. No statistically significant difference was observed between both groups in terms of severity and rate of bleeding, pneumothorax, or duration of hospital stay (p value ranging from 0.419 to 0.914). Conclusion This preliminary study on a limited number of patients suggests that TBLC appears safe in those in whom lung biopsy is at high-risk of complications according to their age, BMI, lung impairment, and cardiac comorbidities.

Abstract Background Although increasing data supports the use of transbronchial lung cryobiopsies (TBLCs) for the diagnosis of diffuse parenchymal lung diseases (DPLDs), its role as an alternative to surgical lung biopsy (SLB) is still under debate. The aim of this study was to assess the benefit of additional SLBs performed in selected patients after TBLCs. Method We conducted a multicentric Belgian prospective trial in which SLBs were performed after TBLCs when the pathological diagnosis was uncertain or if a nonspecific interstitial pneumonia (NSIP) pattern was observed hypothesizing that SLB could provide additional information and that a co-existent UIP pattern could be missed. Results Eighty-one patients with TBLCs performed for a DPLD were included in the study between April 2015 and December 2019. A specific histological diagnosis was obtained in 52 patients (64%) whereas no pathological diagnosis following TBLCs was obtained in 13 patients (16%) and a pattern suggestive of a NSIP was observed in 16 patients (20%). Fourteen out of these 29 patients had SLBs after TBLCs. SLBs showed a UIP pattern in 11 (79%), a pattern suggestive of a hypersensitivity pneumonitis in two (14%) and a NSIP pattern in one patient (7%). Among the 16 patients with pathological NSIP following TBLCs, six underwent a SLBs showing a UIP in five and confirming a NSIP in one patient only. A retrospective pathological analysis of patients having both procedures showed a lower diagnostic confidence and agreement among pathologists for TBLCs compared to SLBs. Major factors underlying the added value of SLBs were the bigger size of the sample as well as the subpleural localization of the biopsies. Conclusions TBLCs are useful in the setting of DPLDs with a good diagnostic yield. However, our study suggests that SLB provides critical additional information in case TBLCs are inconclusive or show a pattern suggestive of a NSIP, questioning the accuracy of TBLC to adequately identify this histological pattern.

Abstract Background Post-mortem studies can provide important information for understanding new diseases and small autopsy case series have already reported different findings in COVID-19 patients. Methods We evaluated whether some specific post-mortem features are observed in these patients and if these changes are related to the presence of the virus in different organs. Complete macroscopic and microscopic autopsies were performed on different organs in 17 COVID-19 non-survivors. Presence of SARS-CoV-2 was evaluated with immunohistochemistry (IHC) in lung samples and with real-time reverse-transcription polymerase chain reaction (RT-PCR) test in the lung and other organs. Results Pulmonary findings revealed early-stage diffuse alveolar damage (DAD) in 15 out of 17 patients and microthrombi in small lung arteries in 11 patients. Late-stage DAD, atypical pneumocytes, and/or acute pneumonia were also observed. Four lung infarcts, two acute myocardial infarctions, and one ischemic enteritis were observed. There was no evidence of myocarditis, hepatitis, or encephalitis. Kidney evaluation revealed the presence of hemosiderin in tubules or pigmented casts in most patients. Spongiosis and vascular congestion were the most frequently encountered brain lesions. No specific SARS-CoV-2 lesions were observed in any organ. IHC revealed positive cells with a heterogeneous distribution in the lungs of 11 of the 17 (65%) patients; RT-PCR yielded a wide distribution of SARS-CoV-2 in different tissues, with 8 patients showing viral presence in all tested organs (i.e., lung, heart, spleen, liver, colon, kidney, and brain). Conclusions In conclusion, autopsies revealed a great heterogeneity of COVID-19-associated organ injury and the remarkable absence of any specific viral lesions, even when RT-PCR identified the presence of the virus in many organs.

Introduction: Epidermal growth factor receptor (EGFR) mutations are frequently found in patients with lung adenocarcinomas, 90% being deletions in exon 19 or point mutation in exon 21. Three generations of tyrosine kinase inhibitors (TKIs) targeting EGFR mutations are available and have changed patient prognosis but less data is available on exon 18 mutations and their sensitivity to TKI therapy. Exon 18 delE709_T710insD accounts for 0.06% (16/27,294) of all EGFR mutations and is an oncogenic driver. Several partial responses to afatinib have been described. Case description: We report the first case, to the best of our knowledge, of the complete response to afatinib of a 57-year-old patient with stage IV lung adenocarcinoma with a delE709_T710insD mutation in the EGFR gene detected by next-generation sequencing. Oral afatinib was prescribed and despite treatment interruptions and dosage tapering due to cutaneous adverse events, a complete response was achieved 12 months after treatment initiation and is currently maintained at 17 months. Conclusion: When EGFR mutation is suspected, complete DNA sequencing of exons 18 to 21 should be carried out and we suggest that afatinib should be the first-line treatment for exon 18 delE709_T710insD-mutated advanced lung adenocarcinomas.

Background. An increasing number of pulmonary nodules of unknown nature are detected as a result of screening by CT in high lung cancer risk patients. Objectives. The purposes of this study were to assess the diagnostic yield of electromagnetic navigation bronchoscopy (ENB) combined with transbronchial lung cryobiopsy (TBLC) and to compare it with standard transbronchial biopsy (TBB) in pulmonary nodules of less than 2 cm in diameter. Methods. We prospectively included 32 patients (18 men and 14 women, mean age 68 ± 9 years) with nodules of less than 2 cm in diameter and no metastasis at 18FDG PET-CT. The nodule position was determined by ENB, radial endobronchial ultrasonography miniprobe, and fluoroscopy. Eight samples were obtained, six by TBB and two by TBLC. Results. Nodule diameter averaged 16 ± 3 mm. Twenty-five nodules were malignant and 18 were surgically resected. Surgery was avoided in four patients as the biopsies revealed a benign disease. The samples obtained by TBLC were five times larger than those by TBB. The diagnostic yields of TBLC and TBB were 69% and 38%, respectively (p=0.017). Adverse events consisted in 15 mild or moderate bleedings and one pneumothorax. Conclusions. In the setting of peripheral pulmonary lesions of less than 20 mm in diameter, ENB-combined TBLC is feasible and safe, provides larger samples, and has higher diagnostic yield than TBB.

Background. Transbronchial lung cryobiopsies (TBLCs) are a promising diagnostic tool in the setting of diffuse parenchymal lung diseases (DPLDs). However, no comparison with surgical lung biopsy (SLB) in the same patient is available. Methods. The diagnostic yield and safety data of TBLCs, as well as the result of SLB performed after TBLCs, were analysed in a multicentric Belgian study. A SLB was performed after TBLCs in absence of a definite pathological diagnosis or if a NSIP pattern was observed without related condition identified following multidisciplinary discussion. Results. Between April 2015 and November 2016, 30 patients were included. Frequent complications included pneumothorax (20%) and bleeding (severe 7%, moderate 33%, and mild 53%). There was no mortality. The overall diagnostic yield was 80%. A SLB was performed in six patients (three without definite histological pattern and three with an NSIP). The surgical biopsy changed the pathological diagnosis into a UIP pattern in five patients and confirmed a NSIP pattern in one patient. Conclusion. TBLCs are useful in the diagnostic work-up of DPLDs avoiding a SLB in 80% of the patients. However, surgical biopsies, performed as a second step after TBLCs because of an indefinite diagnosis or a NSIP pattern, provide additional information supporting the interest of a sequential approach in these patients.

The mechanisms of brain death (BD)-induced lung injury remain incompletely understood, as uncertainties persist about time-course and relative importance of mechanical and humoral perturbations.Brain death was induced by slow intracranial blood infusion in anesthetized pigs after randomization to placebo (n = 11) or to methylprednisolone (n = 8) to inhibit the expression of pro-inflammatory mediators. Pulmonary artery pressure (PAP), wedged PAP (PAWP), pulmonary vascular resistance (PVR) and effective pulmonary capillary pressure (PCP) were measured 1 and 5 hours after Cushing reflex. Lung tissue was sampled to determine gene expressions of cytokines and oxidative stress molecules, and pathologically score lung injury.Intracranial hypertension caused a transient increase in blood pressure followed, after brain death was diagnosed, by persistent increases in PAP, PCP and the venous component of PVR, while PAWP did not change. Arterial PO2/fraction of inspired O2 (PaO2/FiO2) decreased. Brain death was associated with an accumulation of neutrophils and an increased apoptotic rate in lung tissue together with increased pro-inflammatory interleukin (IL)-6/IL-10 ratio and increased heme oxygenase(HO)-1 and hypoxia inducible factor(HIF)-1 alpha expression. Blood expressions of IL-6 and IL-1β were also increased. Methylprednisolone pre-treatment was associated with a blunting of increased PCP and PVR venous component, which returned to baseline 5 hours after BD, and partially corrected lung tissue biological perturbations. PaO2/FiO2 was inversely correlated to PCP and lung injury score.Brain death-induced lung injury may be best explained by an initial excessive increase in pulmonary capillary pressure with increased pulmonary venous resistance, and was associated with lung activation of inflammatory apoptotic processes which were partially prevented by methylprednisolone.

ObjectivesThere is a classical distinction based on clinical criteria between acquired and congenital cholesteatomas. To determine if these two types of lesions show different immunohistochemical features, we have studied the expression patterns of three distinctive galectins (animal lectins implied especially in cellular proliferation and apoptosis) in both types of cholesteatomas and compared it to their expression patterns in external auditory canal skin.MethodsOur study is based on nine acquired and eight congenital cholesteatomas, obtained from children during ear surgery. Six specimens of normal adult auditory meatal skin served as control. Specimens were analyzed by immunohistochemistry using monoclonal antibodies with galectin-1 and galectin-3, and a polyclonal antibody with galectin-7.ResultsWe did not observe any differences in the galectin distribution pattern between congenital and acquired pediatric cholesteatomas. Compared to the control group, cholesteatomas present some particular features. There was no expression of galectin-1 and a lower expression of galectin-3 in the epithelium. Furthermore, we observed a preferentially nuclear distribution of galectin-7 in cholesteatomas, whereas it is essentially cytoplasmic in the control group.ConclusionThe data reported in this study suggest, on the basis of a lesser marked galectin-3 in cholesteatomas epithelium compared with an external auditory canal skin, that an immature keratinocytes population is at the origin of these lesions and that galectin-3 and galectin-7 play a part in the capacity as apoptosis modulators. Our study does not establish a difference in the galectin expressions of congenital and acquired cholesteatomas, but it constitutes however an additional argument in favor of the "undifferentiated" origin of keratinocytes in cholesteatomas.

Recently, Next Generation Sequencing (NGS) has begun to supplant other technologies for gene mutation testing that is now required for targeted therapies. However, transfer of NGS technology to clinical daily practice requires validation.We validated the Ion Torrent AmpliSeq Colon and Lung cancer panel interrogating 1850 hotspots in 22 genes using the Ion Torrent Personal Genome Machine. First, we used commercial reference standards that carry mutations at defined allelic frequency (AF). Then, 51 colorectal adenocarcinomas (CRC) and 39 non small cell lung carcinomas (NSCLC) were retrospectively analyzed.Sensitivity and accuracy for detecting variants at an AF >4% was 100% for commercial reference standards. Among the 90 cases, 89 (98.9%) were successfully sequenced. Among the 86 samples for which NGS and the reference test were both informative, 83 showed concordant results between NGS and the reference test; i.e. KRAS and BRAF for CRC and EGFR for NSCLC, with the 3 discordant cases each characterized by an AF

Using a series of 105 renal cell carcinomas (RCCs) we investigated whether features quantitatively describing the appearance of Feulgen‐stained nuclei and, more particularly, of their chromatin (on the basis of computer‐assisted microscopy) can contribute any significant prognostic information. Thirty morphonuclear and 8 nuclear DNA content‐related variables were thus generated. The actual prognostic values of this set of cytometric variables was compared (by means of discriminant statistical analysis) to conventional diagnostic and/or prognostic markers including histopathological grades, tumour invasion levels and the presence or absence of metastases. We obtained complete clinical follow‐ups for 49 of the 105 RCC patients under study, making it possible to define a subset of patients with a bad prognosis (i.e., who died in the 12 months following nephrectomy) and a subset of patients with a good prognosis (i.e., who survived at least 24 months following nephrectomy). An original method of data analysis related to artificial intelligence (decision tree induction) enabled a strong prognostic model to be set up. In the case of 10 new patients, this model identified all the dead patients as having a bad survival status, with a total of 8 correct predictions. Another prognostic model similarly generated enabled the correct predictions to be confirmed.

Primary graft dysfunction (PGD) and bronchiolitis obliterans (BO) are the leading causes of morbidity and mortality after lung transplantation. Reports from clinical and rodent models suggest the implication of IL-17A in either PGD or BO. We took advantage of the heterotopic trachea transplantation model in mice to study the direct role of IL-17A in post-transplant airway lesions. Across full MHC barrier, early lesions were controlled in IL-17A(-/-) or anti-IL17 treated recipients. In contrast, IL-17A deficiency did not prevent subsequent obliterative airway disease (OAD). Interestingly, this early protection occurred also in syngeneic grafts and was accompanied by a decrease in cellular stress, as attested by lower HSP70 mRNA levels, suggesting the involvement of IL-17A in ischemia-reperfusion injury (IRI). Furthermore, persistence of multipotent CK14(+) epithelial stem cells underlined allograft protection afforded by IL-17A deficiency or neutralisation. Recipient-derived γδ(+) and CD4(+) T cells were the major source of IL-17A. However, lesions still occurred in the absence of each subset, suggesting a high redundancy between the innate and adaptive IL-17A producing cells. Notably, a double depletion significantly diminished lesions. In conclusion, this work implicated IL-17A as mediator of early post-transplant airway lesions and could be considered as a potential therapeutic target in clinical transplantation.

Abstract??The autopsy has long been regarded as an important tool for clinical confrontation, education and quality assurance. The aims of this study were to examine the correlation between the clinical diagnosis and autopsy findings in adult patients who died in an intensive care unit (ICU) and to identify the types of errors in diagnosis to improve quality of care. Autopsies from 289 patients who died in the ICU during a 2-year period were studied. Post-mortem examination revealed unexpected findings in 61 patients (21%) including malignancy, pulmonary embolism, aspergillosis, myocardial or mesenteric infarction and unsuspected bacterial, viral or fungal infection. These unexpected findings were classified as Goldman class I errors in 17 (6%), class II in 38 (13%) and class III in six (2%) cases. Although the incidence of unexpected findings with clinical significance was low, post-mortem examination remains a valuable source of pertinent information that may improve the management of ICU patients. [ABSTRACT FROM AUTHOR]

Thyroid transcription factor 1 (TTF-1) plays a key role in morphogenesis of the lungs and is expressed in up to 90% of pulmonary small cell carcinomas. This explains why this marker is frequently used in the search for the primary origin of metastatic endocrine tumours. Here we report on a TTF-1 expressing mixed endocrine-exocrine carcinoma of the common bile duct in a patient with pulmonary nodules that did not appear to be neoplastic. TTF-1 positivity in pulmonary and extrapulmonary neuroendocrine tumours is reviewed, and we conclude that TTF-1 expression in neuroendocrine tumours of the small-cell type are not uncommon at extrapulmonary locations. Therefore, immunohistochemistry for TTF-1 in such tumours should be interpreted with caution.