A significant proportion of classic Hodgkin lymphoma recurrences represents clonally unrelated second primary lymphoma.

Despite high cure rates in classic Hodgkin lymphoma (cHL), relapses are observed. Whether relapsed cHL represents second primary lymphoma or an underlying T-cell lymphoma (TCL) mimicking cHL is underinvestigated. To analyze the nature of cHL recurrences, in-depth clonality testing of immunoglobulin (Ig) and T-cell receptor (TCR) rearrangements was performed in paired cHL diagnoses and recurrences among 60 patients, supported by targeted mutation analysis of lymphoma-associated genes. Clonal Ig rearrangements were detected by next-generation sequencing (NGS) in 69 of 120 (58%) diagnoses and recurrence samples. The clonal relationship could be established in 34 cases, identifying clonally related relapsed cHL in 24 of 34 patients (71%). Clonally unrelated cHL was observed in 10 of 34 patients (29%) as determined by IG-NGS clonality assessment and confirmed by the identification of predominantly mutually exclusive gene mutations in the paired cHL samples. In recurrences of >2 years, ∼60% of patients with cHL for whom the clonal relationship could be established showed a second primary cHL. Clonal TCR gene rearrangements were identified in 14 of 125 samples (11%), and TCL-associated gene mutations were detected in 7 of 14 samples. Retrospective pathology review with integration of the molecular findings were consistent with an underlying TCL in 5 patients aged >50 years. This study shows that cHL recurrences, especially after 2 years, sometimes represent a new primary cHL or TCL mimicking cHL, as uncovered by NGS-based Ig/TCR clonality testing and gene mutation analysis. Given the significant therapeutic consequences, molecular testing of a presumed relapse in cHL is crucial for subsequent appropriate treatment strategies adapted to the specific lymphoma presentation.

Reliability of whole mount radical prostatectomy histopathology as the ground truth for artificial intelligence assisted prostate imaging.

The development of artificial intelligence-based imaging techniques for prostate cancer (PCa) detection and diagnosis requires a reliable ground truth, which is generally based on histopathology from radical prostatectomy specimens. This study proposes a comprehensive protocol for the annotation of prostatectomy pathology slides. To evaluate the reliability of the protocol, interobserver variability was assessed between five pathologists, who annotated ten radical prostatectomy specimens consisting of 74 whole mount pathology slides. Interobserver variability was assessed for both the localization and grading of PCa. The results indicate excellent overall agreement on the localization of PCa (Gleason pattern ≥ 3) and clinically significant PCa (Gleason pattern ≥ 4), with Dice similarity coefficients (DSC) of 0.91 and 0.88, respectively. On a per-slide level, agreement for primary and secondary Gleason pattern was almost perfect and substantial, with Fleiss Kappa of .819 (95% CI .659-.980) and .726 (95% CI .573-.878), respectively. Agreement on International Society of Urological Pathology Grade Group was evaluated for the index lesions and showed agreement in 70% of cases, with a mean DSC of 0.92 for all index lesions. These findings show that a standardized protocol for prostatectomy pathology annotation provides reliable data on PCa localization and grading, with relatively high levels of interobserver agreement. More complicated tissue characterization, such as the presence of cribriform growth and intraductal carcinoma, remains a source of interobserver variability and should be treated with care when used in ground truth datasets.

Discrepancies in digital hematopathology diagnoses for consultation and expert panel analysis.

Digital pathology with whole-slide imaging (WSI) has a large potential to make the process of expert consultation and expert panel diagnosis more rapid and more efficient. However, comparison with the current methods is necessary for validation of the technique. In this study, we determined if digital assessment of whole-slide images of hematopathology specimens with a focus on the assessment of lymphoma can be used for consultation and panel diagnostics. Ninety-three histological specimens with a suspicion for lymphoma were assessed both with conventional microscopy and digital microscopy with a wash out period between assessments. A consensus diagnosis was based on full concordance between the pathologists or, in case of discordances, was reached at a joint session at a multi-headed microscope. In 81% of the cases, there was a full concordance between digital and light microscopical assessment for all three pathologists. Discordances between conventional microscopy and digital pathology were present in 3% of assessments. In comparison with the consensus diagnosis, discordant diagnoses were made in 5 cases with digital microscopy and in 3 cases with light microscopy. The reported level of confidence and need for additional investigations were similar between assessment by conventional and by digital microscopy. In conclusion, the performance of assessment by digital pathology is in general comparable with that of conventional light microscopy and pathologists feel confident using digital pathology for this subspecialty.

Coxiella burnetii in non-Hodgkin lymphoma tissue samples: Innocent until proven otherwise?

PURPOSE: Coxiella burnetii has been suggested as a potential cause of B-cell non-Hodgkin lymphoma (B-NHL), as C. burnetii was detected in B-NHL tissues. To further investigate this potential relationship, we hypothesized that among subjects previously exposed to C. burnetii, the bacterium is more frequently detectable in tissues of patients with B-NHL (cases) compared to patients without B-NHL (controls). METHODS: We aimed to evaluate this hypothesis by assessing the presence of C. burnetii with polymerase chain reaction (PCR), immunofluorescence staining (IF) and fluorescent in-situ hybridization (FISH). Eligible patients were those previously exposed to C. burnetii. RESULTS: Samples were available for 13 cases and 16 controls. C. burnetii was demonstrated in tissues of 8/29 patients in total (28%), with either PCR, IF or FISH: in 5/13 cases (38%) and 3/16 controls (19%), p = 0.41. Negative and positive control samples were all negative and positive appropriately for all three diagnostic methods. CONCLUSIONS: In patients previously exposed to C. burnetii the bacterium was detected in tissue samples from subjects with and without B-NHL, without significant differences in the proportion positive samples. Therefore, we conclude that detection of C. burnetii in tissues of patients previously exposed to C. burnetii is a non-specific finding.

Case report: Coxiella burnetii vascular infection and lymphoma in the Netherlands.

OBJECTIVES AND DESIGN: Non-Hodgkin lymphoma has been linked to infection with Coxiella burnetii, potentially through overproduction of IL-10 during infection with C. burnetii. MATERIALS AND METHODS: Description of a case report. RESULTS: We describe a patient with retroperitoneal non-Hodgkin lymphoma and vascular infection with C. burnetii. Immunofluorescence staining and fluorescence in situ hybridization targeting specific C. burnetii 16S rRNA were performed on the retroperitoneal lymphoma tissue sample obtained at diagnosis of NHL. Both were strongly positive for the presence of C. burnetii. CONCLUSIONS: This case provokes questions regarding a potential association between C. burnetii and NHL, and underlines the importance of further exploration of this association.

EGFR and KRAS mutations in lung carcinomas in the Dutch population: increased EGFR mutation frequency in malignant pleural effusion of lung adenocarcinoma.

BACKGROUND: Frequencies of EGFR and KRAS mutations in non-small cell lung cancer (NSCLC) have predominantly been determined in East Asian and North American populations, showing large differences between these populations. The aim of the present study was to determine the frequency of EGFR and KRAS mutations in NSCLC in the West European Dutch population in primary carcinomas and different metastatic locations. METHODS: EGFR (exons 19, 20 and 21) and KRAS (exons 2 and 3) mutation test results of NSCLC samples of patients in 13 hospitals were collected. The tests were performed on paraffin-embedded tissue or cytological material of primary and metastatic lung carcinomas. RESULTS: EGFR mutations were detected in 71/778 (9.1 %) tested patients; in 66/620 (10.6 %) adenocarcinomas. EGFR mutations were significantly more often detected in female than in male patients (13.4 % vs. 5.5 %, p < 0.001). KRAS mutations were found in 277 out of 832 (33.3 %) tested patients; in 244/662 (36.9 %) adenocarcinomas. A significantly increased frequency of EGFR mutations was observed in patients with malignant pleural/pericardial effusions (26.5 %; odds ratio (OR) 2.80, 95 % confidence interval (CI) 1.22-6.41), whereas the frequency of KRAS mutations was significantly decreased (18.8 %; OR 0.35, 95 % CI 0.14-0.86). CONCLUSIONS: In the investigated Dutch cohort, patients with malignant pleural/pericardial effusion of lung adenocarcinoma have an increased frequency of EGFR mutations. The overall frequency of EGFR mutations in lung adenocarcinomas in this West European population is within the frequency range of North American and South European populations, whereas KRAS mutation frequency is higher than in any population described to date.

A girl with autoimmune cytopenias, nonmalignant lymphadenopathy, and recurrent infections.

We describe a girl, now 9 years of age, with chronic idiopathic thrombocytopenic purpura, persistent nonmalignant lymphadenopathy, splenomegaly, recurrent infections, and autoimmune hemolytic anemia. Her symptoms partly fit the definitions of both autoimmune lymphoproliferative syndrome (ALPS) and common variable immunodeficiency disorders (CVIDs). Genetic analysis showed no abnormalities in the ALPS-genes FAS, FASLG, and CASP10. The CVID-associated TACI gene showed a homozygous polymorphism (Pro251Leu), which is found also in healthy controls.