Diphtheritic myocarditis: a case report, with toxinmediated complications and multi-organ involvement

The re-emergence of diphtheria in South Africa in recent years warns of incomplete vaccination coverage. Recent outbreaks have been associated with a high mortality rate, due to late presentation, limited access to antitoxin and the occurrence of serious systemic complications. Death due to diphtheria is most commonly associated with diphtheritic myocarditis, which presents with heart failure, cardiogenic shock and conduction abnormalities. This case highlights the key clinical features and systemic complications, and examines the reasons for the return of diphtheria in our community.

A high-resolution 3D atlas of the spectrum of tuberculous and COVID-19 lung lesions

Our current understanding of the spectrum of TB and COVID-19 lesions in the human lung is limited by a reliance on low-resolution imaging platforms that cannot provide accurate 3D representations of lesion types within the context of the whole lung. To characterize TB and COVID-19 lesions in 3D, we applied micro/nanocomputed tomography to surgically resected, postmortem, and paraffin-embedded human lung tissue. We define a spectrum of TB pathologies, including cavitary lesions, calcium deposits outside and inside necrotic granulomas and mycetomas, and vascular rearrangement. We identified an unusual spatial arrangement of vasculature within an entire COVID-19 lobe, and 3D segmentation of blood vessels revealed microangiopathy associated with hemorrhage. Notably, segmentation of pathological anomalies reveals hidden pathological structures that might otherwise be disregarded, demonstrating a powerful method to visualize pathologies in 3D in TB lung tissue and whole COVID-19 lobes. These findings provide unexpected new insight into the spatial organization of the spectrum of TB and COVID-19 lesions within the framework of the entire lung.

Chemokine Receptor-4 Targeted PET/CT Imaging with 68Ga-Pentixafor in Head and Neck Cancer-A Comparison with 18F-FDG and CXCR4 Immunohistochemistry

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is common, and its incidence is increasing, particularly in HIV-infected individuals who present with more aggressive disease. Despite aggressive treatment, the prognosis remains poor because of resistance to chemoradiation therapy. So far, studies report very low [68Ga]Ga-Pentixafor avidity in HNSCC. This study investigated the diagnostic performance of CXCR4-directed imaging of carcinoma of the oral cavity, oropharynx, and nasopharynx with positron emission tomography/computed tomography (PET/CT) using the radiolabelled chemokine ligand [68Ga]Ga-Pentixafor and explored its ability to quantify CXCR4 expression in vivo.

MATERIALS AND METHODS

In this prospective cross-sectional study, twenty-three (23) patients aged 52.9 ± 10.4 (19.6), 17 males and 6 females with primarily diagnosed (n = 17) or pre-treated (n = 6) SCC of the oral cavity (OCSCC, n = 11), oropharynx (OPSCC, n = 9), nasopharynx (NPSCC, n = 2) and unknown primary (n = 1) underwent imaging with [68Ga]Ga-Pentixafor-PET/CT. In 16/23 patients 2-[18F]fluoro-2-deoxy-D-glucose ([18F]F-FDG) served as a standard reference. All lesions were visually rated using a 5-point Likert scale. For both tracers, maximum standardized uptake values (SUVmax) and the total lesion uptake (TLU) were recorded and compared using the Wilcox-signed rank test. In addition, the tumor-to-background ratios were derived using the liver (TLR), spleen (TSR), and posterior cervical muscles (TMR) as background. The relationships between the SUVs of the two tracers were assessed using the Spearman correlation. CXCR4 immunohistochemistry (IHC) staining was correlated with 68Ga-Pentixafor-PET/CT in 21/23 patients.

RESULTS

Ninety-one percent (21/23) of tumors were visually detected on [68Ga]Ga-Pentixafor; however, [68Ga]Ga-Pentixafor was less intense compared with [18F]F-FDG-PET. Quantitative analysis showed higher [18F]F-FDG SUVmax in comparison with [68Ga]Ga-Pentixafor (16 ± 6.7 vs. 5.8 ± 2.6 g/mL, p = 0.011) and SUVmean (9.3 ± 4.1 vs. 3± 1.6 g/mL, p < 0.001) and TBR 4.9 ± 2.3 vs. 2.36 ± 1.4 p = 0.014. Nasopharyngeal cancer demonstrated more intense tracer accumulation than oropharyngeal and oral cavity malignancies. CXCR4 IHC staining was positive in 15/21 patients, and there was a statistically significant correlation between IHC staining and [68Ga]Ga-Pentixafor SUVmean r = 0.5 p = 0.027, and performance status r = 0.83 p = 0.0104.

CONCLUSIONS

In conclusion, although [68Ga]Ga-Pentixafor cannot replace [18F]F-FDG as a diagnostic tool because of its lower avidity, the correlation between CXCR4 targeted 68Ga-Pentixafor PET imaging and CXCR4 IHC staining indicates the potential of 68Ga-Pentixafor as an effective tool for selecting patients who may benefit from therapies targeting CXCR4. In addition, [68Ga]Ga-Pentixafor has no physiological brown fat uptake, which often obscures cervical lesions on [18F]F-FDG PET/CT imaging.

Detection of Mycobacterium tuberculosis in human tissue via RNA in situ hybridization

Rationale

Accurate TB diagnosis is hampered by the variable efficacy of the widely-used Ziehl-Neelsen (ZN) staining method to identify Mycobacterium tuberculosis ( Mtb ) acid-fast bacilli (AFB). Here, we sought to circumvent this current limitation through direct detection of Mtb mRNA.

Objectives

To employ RNAscope to determine the spatial distribution of Mtb mRNA within tuberculous human tissue, to appraise ZN-negative tissue from confirmed TB patients, and to provide proof-of-concept of RNAscope as a platform to inform TB diagnosis and Mtb biology.

Methods

We examined ante- and postmortem human TB tissue using RNAscope to detect Mtb mRNA and a dual ZN/immunohistochemistry staining approach to identify AFB and bacilli producing antigen 85B (Ag85B).

Measurements and main results

We adapted RNAscope for Mtb and identified intact and disintegrated Mtb bacilli and intra- and extracellular Mtb mRNA. Mtb mRNA was distributed zonally within necrotic and non-necrotic granulomas. We also found Mtb mRNA within, and adjacent to, necrotic granulomas in ZN-negative lung tissue and in Ag85B-positive bronchial epithelium. Intriguingly, we observed accumulation of Mtb mRNA and Ag85B in the cytoplasm of host cells. Notably, many AFB were negative for Ag85B staining. Mtb mRNA was observed in ZN-negative antemortem lymph node biopsies.

Conclusions

RNAscope has diagnostic potential and can guide therapeutic intervention as it detects Mtb mRNA and morphology in ZN-negative tissues from TB patients, and Mtb mRNA in ZN-negative antemortem biopsies, respectively. Lastly, our data provide evidence that at least two phenotypically distinct populations of Mtb bacilli exist in vivo .

Evolution of testing for the diagnosis of human papillomavirus (HPV) status in head and neck squamous cell carcinoma: Where from and where to?

Human papillomavirus (HPV) is causally associated with head and neck squamous cell carcinomas with the strongest association in the oropharynx. HPV-associated oropharyngeal carcinomas have a different pathogenesis with distinct clinical features and better prognosis than HPV-negative oropharyngeal carcinomas which impacts staging and prognosis. It is, therefore, of clinical significance to accurately determine the HPV status, particularly in oropharyngeal carcinomas. In this review, the different test methods that are used for characterizing HPV status in head and neck squamous cell carcinomas, both conventional methods (p16 immunohistochemistry, HPV DNA in-situ hybridization, HPV DNA PCR, HPV E6/E7 mRNA RT-PCR, HPV RNA in-situ hybridization) as well as emerging novel approaches (HPV circulating tumour DNA, HPV16 E6 antibodies, oral HPV DNA/mRNA PCR), are discussed. Currently, a combined testing approach is favoured, using a sequential strategy of screening with p16 immunohistochemistry and confirming with HPV DNA PCR. HPV RNA in-situ hybridization could potentially serve as a single test owing to its good sensitivity and specificity. The use of liquid biopsies is gaining momentum with HPV circulating tumour DNA as the frontrunner in demonstrating promising clinical utility for early detection in HPV-associated oropharyngeal carcinomas. HPV16 E6 antibodies and oral HPV DNA PCR has potential utility as adjunct tests to aid diagnosis. In this rapidly evolving HPV testing landscape, we as clinicians and laboratorians must evolve and advocate for access to cost-effective accurate HPV testing globally.

Spatial distribution of Mycobacterium tuberculosis mRNA and secreted antigens in acid-fast negative human antemortem and resected tissue

BACKGROUND

The ability to detect evidence of Mycobacterium tuberculosis (Mtb) infection within human tissues is critical to the study of Mtb physiology, tropism, and spatial distribution within TB lesions. The capacity of the widely-used Ziehl-Neelsen (ZN) staining method for identifying Mtb acid-fast bacilli (AFB) in tissue is highly variable, which can limit detection of Mtb bacilli for research and diagnostic purposes. Here, we sought to circumvent these limitations via detection of Mtb mRNA and secreted antigens in human tuberculous tissue.

METHODS

We adapted RNAscope, an RNA in situ hybridisation (RISH) technique, to detect Mtb mRNA in ante- and postmortem human TB tissues and developed a dual ZN/immunohistochemistry staining approach to identify AFB and bacilli producing antigen 85B (Ag85B).

FINDINGS

We identified Mtb mRNA within intact and disintegrating bacilli as well as extrabacillary mRNA. Mtb mRNA was distributed zonally within necrotic and non-necrotic granulomas. We also found Mtb mRNA within, and adjacent to, necrotic granulomas in ZN-negative lung tissue and in Ag85B-positive bronchiolar epithelium. Intriguingly, we observed accumulation of Mtb mRNA and Ag85B in the cytoplasm of host cells. Notably, many AFB were negative for Ag85B staining. Mtb mRNA was observed in ZN-negative antemortem lymph node biopsies.

INTERPRETATION

RNAscope and dual ZN/immunohistochemistry staining are well-suited for identifying subsets of intact Mtb and/or bacillary remnants in human tissue. RNAscope can identify Mtb mRNA in ZN-negative tissues from patients with TB and may have diagnostic potential in complex TB cases.

FUNDING

Wellcome Leap Delta Tissue Program, Wellcome Strategic Core Award, the National Institutes of Health (NIH, USA), the Mary Heersink Institute for Global Health at UAB, the UAB Heersink School of Medicine.

Comparing 68Ga-Pentixafor,18F-FDG PET/CT and Chemokine Receptor 4 Immunohistochemistry Staining in Breast Cancer: A Prospective Cross Sectional Study

Background. CXCR4 is a chemokine receptor that is frequently overexpressed in invasive breast cancer and plays a major role in tumor proliferation, aggressiveness and metastasis. The aim of this prospective study was to establish the value of CXCR4-directed PET imaging in patients with breast cancer using the novel CXCR4-targeted PET probe 68Ga-Pentixafor by comparing it with 18F-FDG PET/CT (n = 40). Materials and methods. In this prospective cross-sectional study, fifty-one patients with breast cancer aged 36-81 (median (Q1-Q3) 51 (42.5-63)), n = 47 (92%) with initially diagnosed and n = 4 (8%) patients with recurrent breast cancer, underwent CXCR4-targeted PET imaging using 68Ga-Pentixafor. Maximum standardized uptake values (SUVmax), total lesion glycolysis (TLG) or total lesion uptake (TLU), metabolic tumor volume (MTV) and tumor-to-background ratios (TBR) of tumor lesions were measured and correlated with pathological prognostic factors, molecular subtypes and CXCR4 immunohistochemistry (IHC) staining. 18F-FDG PET/CT images were available in 40 of 51 cases (82%) and were compared semi-quantitatively. The patients were followed up for a median of 11 months (range 4-80 months) to determine whether CXCR4 expression correlated with survival. Results. 68Ga-Pentixafor-PET/CT was visually positive in 49/51 (96%) of the cases; in addition, [18F]FDG demonstrated a higher SUVmax compared to 68Ga-Pentixafor. The mean SUVmax was 7.26 ± 2.84 and 18.8 ± 9.1 for 68Ga-Pentixafor and [18F]FDG, respectively. Thirty-seven percent (18/51) of patients had triple-negative breast cancer and 25/51 (49%) had estrogen receptor (ER+) disease. There was a statistically significant correlation between tumor grade, proliferative index (Ki-67) and SUVmax obtained from 68Ga-Pentixafor PET p = 0.002. There was no correlation between the SUVmax obtained from 68Ga-Pentixafor and PET molecular subtypes, estrogen receptor (ER), progesterone receptor (PR) or human epidermal growth factor receptor 2 (HER2) status; however, triple-negative breast cancers had more avid 68Ga-Pentixafor accumulation compared to luminals A and B. The median (Q1-Q3) 68Ga-Pentixafor TLU was significantly higher in HIV-positive (376 (219-881)) compared to HIV-negative (174 (105-557)) breast cancer patients. Conclusions. In conclusion, 68Ga-Pentixafor had a sensitivity of 96% and a specificity of 100% for detecting primary breast cancer; in addition, 68Ga-Pentixafor exhibited significantly higher uptake in patients with higher tumor grade, high proliferative index and triple-negative breast cancer (TNBC), as well as HIV-infected breast cancer patients, highlighting the potential clinical utility and prognostic role of CXCR4-targeted PET imaging in aggressive breast cancer. Notably, 68Ga-Pentixafor complements 18F-FDG by detecting more metastasis in the brain and the skull where FDG has limitations, while 18F-FDG remains superior for detecting skeletal metastasis. Future research should further explore the potential of CXCR4-targeted PET imaging in selecting patients with triple-negative breast cancer and high-grade breast cancer who may benefit from CXCR4-targeted therapies, particularly in the context of HIV co-infection.