Non-canonical EphA2 activation underpins PTEN-mediated metastatic migration and poor clinical outcome in prostate cancer.

BACKGROUND: The key process of mesenchymal to amoeboid transition (MAT), which enables prostate cancer (PCa) transendothelial migration and subsequent development of metastases in red bone marrow stroma, is driven by phosphorylation of EphA2S897 by pAkt, which is induced by the omega-6 polyunsaturated fatty acid arachidonic acid. Here we investigate the influence of EphA2 signalling in PCa progression and long-term survival. METHODS: The mechanisms underpinning metastatic biopotential of altered EphA2 signalling in relation to PTEN status were assessed in vitro using canonical (EphA2D739N) and non-canonical (EphA2S897G) PC3-M mutants, interrogation of publicly available PTEN-stratified databases and clinical validation using a PCa TMA (n = 177) with long-term follow-up data. Spatial heterogeneity of EphA2 was assessed using a radical prostatectomy cohort (n = 67). RESULTS: Non-canonical EphA2 signalling via pEphA2S897 is required for PCa transendothelial invasion of bone marrow endothelium. High expression of EphA2 or pEphA2S897 in a PTENlow background is associated with poor overall survival. Expression of EphA2, pEphA2S897 and the associated MAT marker pMLC2 are spatially regulated with the highest levels found within lesion areas within 500 µm of the prostate margin. CONCLUSION: EphA2 MAT-related signalling confers transendothelial invasion. This is associated with a substantially worse prognosis in PTEN-deficient PCa.

Human Papilloma Virus (HPV) status may impact treatment outcomes in patients with pre-cancerous penile lesions (an eUROGEN Study).

Penile intra-epithelial neoplasia (PeIN) is a known precursor for penile cancer. It may be undifferentiated or differentiated. The former is related to high-risk Human Papilloma Virus (HPV) and associated with p16 over-expression. Patients may present with red patches or lesions on the penis which on occasion may affect sexual activity.This study will assess associations between p16 status, patient parameters, treatment choice and outcomes. Data were collected on patients diagnosed with PeIN, who were referred to a single European Network, between 2008 and 2018. The following parameters were collected utilising patient records: demographics, smoking status, performance status, comorbidities, HPV/p16 status, lichen sclerosus (LS) status, treatment and clinical response. Log rank, Kaplan-Meier, Pearson Chi-Squared and Fishers Exact test were utilised to determine significance. One hundred thirty-seven patients were identified with PeIN and no invasive cancer. Staining for p16 was available in 91 patients and 74 patients were p16+. There were no significant differences in disease-free survival (DFS) for smoking status, performance status, comorbidities and lichen sclerosus, although patients with lichen sclerosus tended to recur sooner. Overall, p16+ patients showed significantly better DFS over p16- patients (n = 67; 10.4 vs 7.4 months; p = 0.023). In p16+ patients receiving treatment with imiquimod alone or with surgery, response rates were 100% vs 54% without imiquimod (n = 56; p = 0.017). In p16- patients receiving treatment with imiquimod alone or with surgery, response rates were 100% vs 56% without imiquimod (n = 17; p = 0.99). Overall 13.6% of patients progressed to cancer. The results indicate treatment combinations with immunotherapy tend to provide better responses despite p16 status. Patients with p16+ disease have a longer disease-free survival. Approximately 14% of patients progress to invasive disease. However, given the limitations in this study, further research is required to confirm these findings.

Intraductal carcinoma of the prostate is an aggressive form of invasive carcinoma and should be graded.

Infiltration of the prostatic ducts by prostatic adenocarcinoma occurs relatively frequently, being most commonly associated with high grade disease. It is now recognised that intraductal carcinoma of the prostate (IDCP) has an associated poor prognosis and this is reflected in its histological, molecular and immunohistochemical features. The current recommendation of the World Health Organization is that IDCP not be taken into consideration when grading prostate adenocarcinoma. It is apparent that Gleason did not differentiate between IDCP and stromal invasive carcinoma when developing and validating his grading system, and recent studies suggest that the incorporation of IDCP grading into the overall grading of the specimen provides additional prognostic information.

Controversial issues in Gleason and International Society of Urological Pathology (ISUP) prostate cancer grading: proposed recommendations for international implementation.

The Gleason Grading system has been used for over 50 years to prognosticate and guide the treatment for patients with prostate cancer. At consensus conferences in 2005 and 2014 under the guidance of the International Society of Urological Pathology (ISUP), the system has undergone major modifications to reflect modern diagnostic and therapeutic practices. The 2014 consensus conference yielded recommendations regarding cribriform, mucinous, glomeruloid and intraductal patterns, the most significant of which was the removal of any cribriform pattern from Gleason grade 3. Furthermore, a Gleason score grouping system was endorsed which consisted of five grades where Gleason score 6 (3+3) was classified as grade 1 which better reflected the mostly indolent behaviour of these tumours. Another issue discussed at the meeting and subsequently endorsed was that in Gleason score 7 cases, the percentage pattern 4 should be recorded. This is especially important in situations where modern active surveillance protocols expand to include men with low volume pattern 4. While major progress was made at the conference, several issues were either not resolved or not discussed at all. Most of these items relate to details of assignment of Gleason score and ISUP grade in specific specimen types and grading scenarios. This detailed review looks at the 2014 ISUP conference results and subsequent literature from an international perspective and proposes several recommendations. The specific issues addressed are percentage pattern 4 in Gleason score 7 tumours, percentage patterns 4 and 5 or 4/5 in Gleason score 8-10 disease, minor (≤5%) high grade patterns when either 2 or 3 patterns are present, level of reporting (core, specimen, case), dealing with grade diversity among site (highest and composite scores) and reporting scores in radical prostatectomy specimens with multifocal disease. It is recognised that for many of these issues, a strong evidence base does not exist, and further research studies are required. The proposed recommendations mostly reflect consolidated expert opinion and they are classified as established if there was prior agreement by consensus and provisional if there was no previous agreement or if the item was not discussed at prior consensus conferences. For some items there are reporting options that reflect the local requirements and diverse practice models of the international urological pathology community. The proposed recommendations provide a framework for discussion at future consensus meetings.

Data Set for the Reporting of Carcinoma of the Renal Pelvis and Ureter-Nephroureterectomy and Ureterectomy Specimens: Recommendations From the International Collaboration on Cancer Reporting (ICCR).

Cancer reporting guidelines have been developed and utilized in many countries throughout the world. The International Collaboration on Cancer Reporting (ICCR), through an alliance of colleges and other pathology organizations in Australasia, United Kingdom, Ireland, Europe, USA, and Canada, has developed comprehensive standardized data sets to provide for global usage and promote uniformity in cancer reporting. Structured reporting facilitates provision of all necessary information, which ensures accurate and comprehensive data collection, with the ultimate aim of improving cancer diagnostics and treatment. The data set for primary carcinoma of the renal pelvis and ureter treated with nephroureterectomy or ureterectomy had input from an expert panel of international uropathologists. This data set was based on current evidence-based practice and incorporated information from the 2016 fourth edition of the World Health Organization (WHO) Bluebook on tumors of the urinary and male genital systems and the 2017 American Joint Committee on Cancer (AJCC) TNM staging eighth edition. This protocol applies to both noninvasive and invasive carcinomas in these locations. Reporting elements are considered to be essential (required) or nonessential (recommended). Required elements include operative procedure, specimens submitted, tumor location, focality and size, histologic tumor type, subtype/variant of urothelial carcinoma, WHO grade, extent of invasion, presence or absence of vascular invasion, status of the resection margins and lymph nodes and pathologic stage. The data set provides a detailed template for the collection of data and it is anticipated that this will facilitate appropriate patient management with the potential to foster collaborative research internationally.

Dataset for reporting of carcinoma of the urethra (in urethrectomy specimens): recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) is a not-for-profit organisation sponsored by the Royal Colleges of Pathologists of Australasia and the United Kingdom, the College of American Pathologists, the Canadian Association of Pathologists in association with the Canadian Partnership Against Cancer, the European Society of Pathology, the American Society of Clinical Pathology and the Faculty of Pathology, Royal College of Physicians of Ireland. Its goal is to produce standardised, internationally agreed-upon, evidence-based datasets for cancer pathology reporting throughout the world. This paper describes the development of a cancer dataset by the multidisciplinary ICCR expert panel for the reporting of carcinoma of the urethra in urethrectomy specimens. The dataset is composed of 'required' (mandatory) and 'recommended' (non-mandatory) elements, which are based on a review of the most recent evidence and supported by explanatory commentary. Fourteen required elements and eight recommended elements were agreed by the international dataset authoring committee to represent the essential/required (core) and recommended (non-core) information for the reporting of carcinoma of the urethra in urethrectomy specimens. Use of an internationally agreed, structured pathology dataset for reporting carcinoma of the urethra (in urethrectomy specimens) will provide the necessary information for optimal patient management, will facilitate consistent data collection and will provide valuable data for research and international benchmarking. The dataset will be valuable for those countries and institutions that are not in a position to develop their own datasets.

Genomic Evaluation of Multiparametric Magnetic Resonance Imaging-visible and -nonvisible Lesions in Clinically Localised Prostate Cancer.

BACKGROUND: The prostate cancer (PCa) diagnostic pathway is undergoing a radical change with the introduction of multiparametric magnetic resonance imaging (mpMRI), genomic testing, and different prostate biopsy techniques. It has been proposed that these tests should be used in a sequential manner to optimise risk stratification. OBJECTIVE: To characterise the genomic, epigenomic, and transcriptomic features of mpMRI-visible and -nonvisible PCa in clinically localised disease. DESIGN, SETTING, AND PARTICIPANTS: Multicore analysis of fresh prostate tissue sampled immediately after radical prostatectomy was performed for intermediate- to high-risk PCa. INTERVENTION: Low-pass whole-genome, exome, methylation, and transcriptome profiling of patient tissue cores taken from microscopically benign and cancerous areas in the same prostate. Circulating free and germline DNA was assessed from the blood of five patients. OUTCOME MEASUREMENT AND STATISTICAL ANALYSIS: Correlations between preoperative mpMRI and genomic characteristics of tumour and benign prostate samples were assessed. Gene profiles for individual tumour cores were correlated with existing genomic classifiers currently used for prognostication. RESULTS AND LIMITATIONS: A total of 43 prostate cores (22 tumour and 21 benign) were profiled from six whole prostate glands. Of the 22 tumour cores, 16 were tumours visible and six were tumours nonvisible on mpMRI. Intratumour genomic, epigenomic, and transcriptomic heterogeneity was found within mpMRI-visible lesions. This could potentially lead to misclassification of patients using signatures based on copy number or RNA expression. Moreover, three of the six cores obtained from mpMRI-nonvisible tumours harboured one or more genetic alterations commonly observed in metastatic castration-resistant PCa. No circulating free DNA alterations were found. Limitations include the small cohort size and lack of follow-up. CONCLUSIONS: Our study supports the continued use of systematic prostate sampling in addition to mpMRI, as avoidance of systematic biopsies in patients with negative mpMRI may mean that clinically significant tumours harbouring genetic alterations commonly seen in metastatic PCa are missed. Furthermore, there is inconsistency in individual genomics when genomic classifiers are applied. PATIENT SUMMARY: Our study shows that tumour heterogeneity within prostate tumours visible on multiparametric magnetic resonance imaging (mpMRI) can lead to misclassification of patients if only one core is used for genomic analysis. In addition, some cancers that were missed by mpMRI had genomic aberrations that are commonly seen in advanced metastatic prostate cancer. Avoiding biopsies in mpMRI-negative cases may mean that such potentially lethal cancers are missed.

Infrared spectral histopathology using haematoxylin and eosin (H&E) stained glass slides: a major step forward towards clinical translation.

Infrared spectral histopathology has shown great promise as an important diagnostic tool, with the potential to complement current pathological methods. While promising, clinical translation has been hindered by the impracticalities of using infrared transmissive substrates which are both fragile and prohibitively very expensive. Recently, glass has been proposed as a potential replacement which, although largely opaque in the infrared, allows unrestricted access to the high wavenumber region (2500-3800 cm-1). Recent studies using unstained tissue on glass have shown that despite utilising only the amide A band, good discrimination between histological classes could be achieved, and suggest the potential of discriminating between normal and malignant tissue. However unstained tissue on glass has the potential to disrupt the pathologist workflow, since it needs to be stained following infrared chemical imaging. In light of this, we report on the very first infrared Spectral Histopathology SHP study utilising coverslipped H&E stained tissue on glass using samples as received from the pathologist. In this paper we present a rigorous study using results obtained from an extended patient sample set consisting of 182 prostate tissue cores obtained from 100 different patients, on 18 separate H&E slides. Utilising a Random Forest classification model we demonstrate that we can rapidly classify four classes of histology of an independent test set with a high degree of accuracy (>90%). We investigate different degrees of staining using nine separate prostate serial sections, and demonstrate that we discriminate on biomarkers rather than the presence of the stain. Finally, using a four-class model we show that we can discriminate normal epithelium, malignant epithelium, normal stroma and cancer associated stroma with classification accuracies over 95%.

Intraductal carcinoma of prostate reporting practice: a survey of expert European uropathologists.

BACKGROUND: It is unclear whether the reported variation in the diagnosis of intraductal carcinoma of the prostate (IDC-P) is due to variable interpretation of borderline morphology, use of different diagnostic criteria or both. AIMS: We sought to determine the degree of variation in the diagnostic criteria and reporting rules for IDC-P in prostate biopsies employed by expert uropathologists. METHODS: A questionnaire survey was circulated to 23 expert uropathologists from 11 European countries. RESULTS: Criteria used for diagnosis of IDC-P included solid intraductal growth (100%), dense cribriform (96%), loose cribriform/micropapillary with nuclear size >6× normal (83%) or comedonecrosis (74%) and dilated ducts >2× normal (39%). 'Nuclear size' was interpreted as nuclear area by 74% and nuclear diameter by 21%. Pure IDC-P in needle biopsies was reported by 100% and Gleason graded by 30%. All would perform immunohistochemistry in such cases to rule out invasive cancer. An IDC-P component associated with invasive cancer would be included in the determination of tumour extent and number of cores involved by 74% and 83%, respectively. 52% would include IDC-P component when grading invasive cancer. 48% would perform immunohistochemistry in solid or cribriform nests with comedonecrosis to exclude IDC-P (17% routinely, 30% if the focus appeared to have basal cells on H&E). 48% graded such foci as Gleason pattern 5 even if immunohistochemistry demonstrated the presence of basal cells. CONCLUSIONS: There is a need for more clarity in the definition of some of the diagnostic criteria for IDC-P as well as for greater standardisation of IDC-P reporting.

Dynamic sentinel lymph node biopsy for penile cancer: a comparison between 1- and 2-day protocols.

OBJECTIVE: To determine the outcome of clinically negative node (cN0) patients with penile cancer undergoing dynamic sentinel node biopsy (DSNB), comparing the results of a 1- and 2-day protocol that can be used as a minimal invasive procedure for staging of penile cancer. PATIENTS AND METHODS: This is a retrospective analysis of 151 cN0 patients who underwent DSNB from 2008 to 2013 for newly diagnosed penile cancer. Data were analysed per groin and separated into groups according to the protocol followed. The comparison of the two protocols involved the number of nodes excised, γ-counts, false-negative rates (FNR), and complication rates (Clavien-Dindo grading system). RESULTS: In all, 280 groins from 151 patients underwent DSNB after a negative ultrasound ± fine-needle aspiration cytology. The 1-day protocol was performed in 65 groins and the 2-day protocol in 215. Statistically significantly more nodes were harvested with the 1-day protocol (1.92/groin) compared with the 2-day protocol (1.60/groin). The FNRs were 0%, 6.8% and 5.1%, for the 1-day protocol, 2-day protocol, and overall, respectively. Morbidity of the DSNB was 21.4% for all groins, and 26.2% and 20.1% for the 1-day and 2-day protocols, respectively. Most of the complications were of Clavien-Dindo Grade 1-2. CONCLUSIONS: DSNB is safe for staging patients with penile cancer. There is a trend towards a 1-day protocol having a lower FNR than a 2-day protocol, albeit at the expense of a slightly higher complication rate.

Intraductal carcinoma of the prostate: interobserver reproducibility survey of 39 urologic pathologists.

The diagnosis of intraductal carcinoma (IDC) of the prostate remains subjective because 3 sets of diagnostic criteria are in use. An internet survey was compiled from 38 photomicrographs showing duct proliferations: 14 signed out as high-grade prostatic intraepithelial neoplasia (HGPIN), 17 IDC, and 7 invasive cribriform/ductal carcinoma. Each image was assessed for the presence of 9 histologic criteria ascribed to IDC. Thirty-nine respondents were asked to rate images as (1) benign/reactive, (2) HGPIN, (3) borderline between HGPIN and IDC, (4) IDC, or (5) invasive cribriform/ductal carcinoma. Intraclass correlation coefficient was 0.68. There was 70% overall agreement with HGPIN, 43% with IDC, and 73% with invasive carcinoma (P < .001, χ(2)). Respondents considered 19 (50%) of 38 cases as IDC candidates, of which 5 (26%) had a two-thirds consensus for IDC; two-thirds consensus for either borderline or IDC was reached in 9 (47%). Two-thirds consensus other than IDC was reached in the remaining 19 of 38 cases, with 15 supporting HGPIN and 4 supporting invasive carcinoma. Findings that differed across diagnostic categories were lumen-spanning neoplastic cells (P < .001), 2× benign duct diameters (P < .001), duct space contours (round, irregular, and branched) (P < .001), papillary growth (P = .048), dense cribriform or solid growth (both P = .023), and comedonecrosis (P = .015). When the 19 of 38 images that attained consensus for HGPIN or invasive carcinoma were removed from consideration, lack of IDC consensus was most often attributable to only loose cribriform growth (5/19), central nuclear maturation (5/19), or comedonecrosis (3/19). Of the 9 histologic criteria, only 1 retained significant correlation with a consensus diagnosis of IDC: the presence of solid areas (P = .038). One case that attained IDC consensus had less than 2× duct enlargement yet still had severe nuclear atypia and nucleomegaly. Six fold nuclear enlargement was not significant (P = .083), although no image had both 6× nuclei and papillary or loose cribriform growth: a combination postulated as sufficient criteria for IDC. Finally, 20.5% of respondents agreed that an isolated diagnosis of IDC on needle biopsy warrants definitive therapy, 20.5% disagreed, and 59.0% considered the decision to depend upon clinicopathologic variables. Although IDC diagnosis remains challenging, we propose these criteria: a lumen-spanning proliferation of neoplastic cells in preexisting ducts with a dense cribriform or partial solid growth pattern. Solid growth, in any part of the duct space, emerges as the most reproducible finding to rule in a diagnosis of IDC. Comedonecrosis is a rarer finding, but in most cases, it should rule in IDC. Duct space enlargement to greater than 2× the diameter of the largest, adjacent benign spaces is usually present in IDC, although there may be rare exceptions.

Should centralized histopathological review in penile cancer be the global standard?

OBJECTIVE: To assess the role of centralized pathological review in penile cancer management. MATERIALS AND METHODS: Newly diagnosed squamous cell carcinomas (SCC) of the penis, including squamous cell carcinoma in situ (CIS), from biopsy specimens were referred from 15 centres to the regional supra-network multidisciplinary team (Sn-MDT) between 1 January 2008 and 30 March 2011. Biopsy histology reports and slides from the respective referring hospitals were reviewed by the Sn-MDT pathologists. The biopsy specimens' histological type, grade and stage reported by the Sn-MDT pathologist were compared with those given in the referring hospital pathology report, as well as with definitive surgery histology. Any changes in histological diagnosis were sub-divided into critical changes (i.e. those that could alter management) and non-critical changes (i.e. those that would not affect management). RESULTS: A total of 155 cases of squamous cell carcinoma or CIS of the penis were referred from 15 different centres in North-West England. After review by the Sn-MDT, the histological diagnosis was changed in 31% of cases and this difference was statistically significant. A total of 60.4% of the changes were deemed to be critical changes that resulted in a significant change in management. When comparing the biopsy histology reported by the Sn-MDT with the final histology from the definitive surgical specimens, a good correlation was generally found. CONCLUSIONS: In the present study a significant proportion of penile cancer histology reports were revised after review by the Sn-MDT. Many of these changes altered patient management. The present study shows that accurate pathological diagnosis plays a crucial role in determining the correct treatment and maximizing the potential for good clinical outcomes in penile cancer. In the case of histopathology, centralization has increased exposure to penile cancer and thereby increased diagnostic accuracy, and should therefore be considered the 'gold standard'.

Whole organ cross-section chemical imaging using label-free mega-mosaic FTIR microscopy.

FTIR chemical imaging has been demonstrated as a promising technique to construct automated systems to complement histopathological evaluation of biomedical tissue samples. The rapid chemical imaging of large areas of tissue has previously been a limiting factor in this application. Consequently, smaller areas of tissue have previously had to be sampled, possibly introducing sampling bias and potentially missing diagnostically important areas. In this report a high spatial resolution chemical image of a whole prostate cross section is shown comprising 66 million pixels. Each pixel represents an area 5.5 × 5.5 µm(2) of tissue and contains a full infrared spectrum providing a chemical fingerprint. The data acquisition time was 14 hours, thus showing that a clinical time frame of hours rather than days has been achieved.

FTIR microspectroscopy of selected rare diverse sub-variants of carcinoma of the urinary bladder.

Urothelial carcinomas of the bladder are a heterogeneous group of tumours, although some histological sub-variants are rare and sparsely reported in the literature. Diagnosis of sub-variants from conventional urothelial carcinoma can be challenging, as they may mimic the morphology of other malignancies or benign tumours and therefore their distinction is important. For the first time, the spectral pathology of some of these sub-variants has been documented by infrared microspectroscopy and an attempt made to profile their biochemistry. It is important not only to identify and separate the cancer-associated epithelial tissue spectra from common tissue features such as stroma or blood, but also to detect the signatures of tumour sub-variants. As shown, their spectroscopic signals can change dramatically as a consequence of differentiation. Example cases are discussed and compared with histological evaluations.

Ultrastructurally confirmed myofibrosarcoma: a series of 10 new cases, with a discussion on diagnostic criteria.

Some view ultrastructure as key to myofibrosarcoma diagnosis, whereas others argue that electron microscopy is too little used in contemporary practice to be considered an important diagnostic tool. These views are discussed in the context of 10 ultrastructurally confirmed cases of myofibrosarcoma, some occurring at rare sites such as skin and penis. Patient age ranged from 21 to 83 years, with a 6:4 male to female ratio. Size ranged from 2 to 7.5 cm and all had infiltrative margins. Histologically, all consisted of variably cellular fascicles of spindle cells with mild to moderately pleomorphic nuclei, small punctate nucleoli, and eosinophilic cytoplasm. All cases showed α-smooth muscle actin positivity and 2 showed very focal weak positivity for desmin. Ultrastructurally, the tumor cells contained rough endoplasmic reticulum, mainly peripheral smooth-muscle myofilaments, and fibronectin fibrils or fibronexus junctions at the cell surface. The most confident diagnosis of myofibrosarcoma is provided by ultrastructural examination. However, given the right histological appearance, use of a panel of antibodies that includes α-smooth muscle actin, desmin, and h-caldesmon, serves as an acceptable practical way of diagnosing myofibrosarcoma.

Heterozygote FANCD2 mutations associated with childhood T Cell ALL and testicular seminoma.

Fanconi anaemia (FA) is an inherited disease with congenital and developmental abnormalities characterised by cellular cross linker hypersensitivity. FA is caused by mutations in any of so far 15 identified FANC genes, which encode proteins that interact in a common DNA damage response (DDR) pathway. Individuals with FA have a high risk of developing acute myeloid leukaemia (AML) and squamous cell carcinoma. An increased cancer risk has been firmly established for carriers of mutations in FANCD1/BRCA2, FANCJ/BRIP1, FANCN/PALB2, RAD51C/FANCO and link the FA pathway to inherited breast and ovarian cancer. We describe a pedigree with FANCD2 mutations c.458T > C (p.Leu153Ser) and c.2715 + 1G > A (p.Glu906LeufsX4) with mild phenotype FA in the index case, T cell ALL in the Leu153Ser heterozygous brother and testicular seminoma in the p.Glu906LeufsX4 heterozygous father. Both FANCD2 alleles were present in the T Cell ALL and the seminoma. This links specific FANCD2 mutations to T cell ALL and seminoma without evidence of allelic loss in the tumour tissue.

FTIR microscopy of biological cells and tissue: data analysis using resonant Mie scattering (RMieS) EMSC algorithm.

Transmission and transflection infrared microscopy of biological cells and tissue suffer from significant baseline distortions due to scattering effects, predominantly resonant Mie scattering (RMieS). This scattering can also distort peak shapes and apparent peak positions making interpretation difficult and often unreliable. A correction algorithm, the resonant Mie scattering extended multiplicative signal correction (RMieS-EMSC), has been developed that can be used to remove these distortions. The correction algorithm has two key user defined parameters that influence the accuracy of the correction. The first is the number of iterations used to obtain the best outcome. The second is the choice of the initial reference spectrum required for the fitting procedure. The choice of these parameters influences computational time. This is not a major concern when correcting individual spectra or small data sets of a few hundred spectra but becomes much more significant when correcting spectra from infrared images obtained using large focal plane array detectors which may contain tens of thousands of spectra. In this paper we show that, classification of images from tissue can be achieved easily with a few (<10) iterations but a reliable interpretation of the biochemical differences between classes could require more iterations. Regarding the choice of reference spectrum, it is apparent that the more similar it is to the pure absorption spectrum of the sample, the fewer iterations required to obtain an accurate corrected spectrum. Importantly however, we show that using three different non-ideal reference spectra, the same unique correction solution can be obtained.