Distinguishing immune-mediated aplastic anaemia (AA) from inherited bone marrow failure syndromes (IBMFS) is critical but challenging. The diagnostic value of paroxysmal nocturnal haemoglobinuria (PNH) clones in this context remains uncertain. We prospectively studied 222 AA patients (median-age 21.5 years, range 0.8–67) who underwent high-sensitivity PNH flow-cytometry (≥0.01%) and next-generation sequencing. Patients were classified as Category 1 (pathogenic/likely pathogenic variants fully explaining phenotype; confirmed IBMFS), Category 2 (single heterozygous variants), Categories 3/4 (variants of uncertain significance or no variants). PNH clones ≥0.01% were detected in 124/222 (55.9%), ≥1% in 73/222 (32.9%), and ≥10% in 27/222 (12.2%). Category 1 IBMFS was identified in 17/222 (7.7%). Among Category 1 patients, only 1/17 (5.9%) had clones ≥1%, and, critically, none had clones ≥10%. At the ≥1% threshold, PNH detection showed 94.1% specificity and 98.3% positive predictive value against IBMFS (odds ratio 9.2, p=0.013). Category 2 patients (15/222, 6.8%) demonstrated PNH frequencies (40.0% at ≥1%) indistinguishable from those of acquired AA (36.4%; p=0.785), supporting an immune-mediated disease mechanism on a genetically permissive background. In this comprehensive single-centre cohort, PNH clones ≥1% demonstrated high specificity (94.1%) and positive predictive value (98.3%) for immune-mediated disease. Notably, heterozygous germline carriers exhibited PNH clone distributions indistinguishable from those in acquired AA. These findings warrant validation in larger multicentre cohorts to establish generalisable diagnostic thresholds.
Sclerosing epithelioid fibrosarcoma (SEF) initially presenting as pulmonary masses is exceptionally rare, and pathological diagnosis based on lung biopsy specimens is challenging. To enhance the understanding of its clinicopathological characteristics and improve diagnostic accuracy, we performed a comprehensive analysis of four such cases, including clinical, radiological, histological, immunohistochemical, and molecular characteristics. The mean age was 43 years, comprising three females and one male. Radiologically, the lesions appeared as solitary or multiple pulmonary masses. Morphologically, in addition to the classic appearance of monomorphic epithelioid cells in cords, nests, or sheets within a sclerotic stroma, the tumours also displayed alveolar-like architecture, pseudoalveolar pattern, adenofibroma-like morphology, and spread through air spaces. Significant pleomorphism and necrosis were observed in some cases, and the stroma could be collagen-poor or lymphocyte-rich. Morphological mimicry was evident: the tumours resembled adenofibroma when entrapping respiratory epithelium, lymphoma in lymphocyte-rich areas, neuroendocrine tumours in biopsies containing compressed atypical cells, and normal alveoli when arranged in an alveolar-like architecture. Immunohistochemically, all cases were positive for MUC4. Molecular analysis revealed EWSR1 rearrangement by fluorescence in situ hybridisation (FISH) in two cases. Notably, one case showed a deletion of chromosome 22 and no EWSR1 rearrangement by FISH, but harboured an EWSR1::CREB3L2 fusion by next-generation sequencing. Furthermore, a separate case exhibited FUS rearrangement independent of EWSR1 involvement. This study demonstrates the diverse morphological characteristics of SEF initially presenting as pulmonary masses, and highlights key diagnostic challenges, which may contribute to improved diagnostic accuracy for such lesions.
Perinatal autopsy services provide critical information to help families understand the cause of a stillbirth or neonatal death, inform future pregnancy care, and contribute to public health data. A well-structured perinatal autopsy service integrates pathology with clinical care, supporting families, healthcare providers, and public health outcomes. Investment in good-quality practice standards, workforce training, and equitable access is essential to realise these benefits. This review discusses the practical considerations for establishing and sustaining a high-quality perinatal autopsy service. Key elements include infrastructure, governance, sustainable funding and the role of a skilled multi-disciplinary team. The importance of standardised reporting using a minimum dataset, culturally sensitive consent processes, and continuing education for referring clinicians is highlighted. Current challenges within the Australian context are discussed.
Hydrops fetalis is defined by abnormal fluid accumulation in at least two fetal compartments, resulting from a range of underlying pathological processes, and with a high mortality at the severe end of the spectrum. Identifying the specific cause is crucial for managing both current and future pregnancies. Despite comprehensive antenatal investigations, including obstetric imaging, serology and genetic testing, many cases of non-immune hydrops fetalis (NIHF) remain unexplained at delivery. Some diagnostic features may not be apparent on ultrasound, with perinatal autopsy providing additional valuable information particularly when structural fetal anomalies are absent. In this review, a structured, phenotype-based approach to autopsy has been developed for cases of indeterminate aetiology, with categories including: NIHF with bilateral cystic hygromas; the pale hydropic baby; NIHF associated with cardiovascular system abnormalities; NIHF with no obvious structural abnormality; and NIHF with prominent ascites. Both genetic and non-genetic causes are considered across all groups, with a particular focus on recently described entities and newly identified underlying aetiologies. Placental examination is also vital and may offer key diagnostic clues, though certain pitfalls must be avoided. Comprehensive evaluation by specialist perinatal pathologists can provide crucial diagnostic information in investigation of NIHF.
Renal amyloidosis is an important cause of kidney injury that is often associated with significant morbidity and mortality. In this study, we aim to characterise the clinicopathological patterns and identify potential prognostic factors in renal amyloidosis at an Australian tertiary referral centre over a decade. A total of 63 biopsy-diagnosed cases of renal amyloidosis from 2011 to 2021 were retrospectively reviewed. Cases were initially subtyped by immunofluorescence and immunohistochemistry. Mass spectrometry was performed when rare subtypes were suspected. Histological characteristics were correlated with clinical parameters at the time of biopsy. The primary outcome was severe renal impairment (SRI), defined as an estimated glomerular filtration rate (eGFR) <10 mL/min/1.73 m2 or commencement of renal replacement therapy. Amyloid light chain (AL) amyloidosis was the most common subtype (79%), followed by amyloid A (AA) (11%), and the rare subtypes included amyloid leukocyte cell-derived chemotactic factor-2 (3.2%); amyloid transthyretin wild-type (1.6%); amyloid apolipoprotein C-II (1.6%); amyloid fibrinogen (1.6%); and amyloid gelsolin amyloidosis (1.6%). Patients with AA amyloidosis were younger than those with other subtypes. The classic histological patterns of common and rare amyloid subtypes, as described in the literature, were replicated in our cohort. Interstitial fibrosis and tubular atrophy had a strong correlation with baseline eGFR and were important prognostic factors for SRI. Nephrotic-range proteinuria showed a trend towards SRI, but amyloid subtype (AL vs AA vs other) did not stratify outcome. Most AL amyloidosis cases (69%) were confirmed to be monoclonal gammopathy of undetermined significance, with a smaller proportion showing an underlying haematological malignancy. All patients with AA subtype had an underlying chronic inflammatory disease condition. We demonstrate classic histopathological features of common and rare subtypes of renal amyloidosis in an Australian cohort. Histological markers at biopsy, indicative of chronic renal damage, have value as prognostic factors.
A rapid method for triaging febrile patients by aetiology (e.g., viral or bacterial infection) using gene expression in peripheral blood (PB) is an intensively researched area. However, gene expression in blood represents a composite sum of gene expression of all the component cell types present in the sample. As a result, numerous genes are measured in most proposed signatures. Herein, we propose a simple ratio-based biomarker (RBB) called direct leukocyte subpopulation-transcript abundance assay (DIRECT LS-TA) that recapitulates gene expressions of a single cell type in PB (i.e., monocytes). Based on single-cell RNA sequencing (scRNAseq) data and bulk expression data, IFI27 and SIGLEC1 are found as interferon-stimulated genes (ISGs) predominantly expressed by monocytes. The DIRECT LS-TA method can use a simple ratio of two genes measured in PB as an RBB to represent the target gene expression in monocytes without the need for monocyte purification. Both scRNAseq and bulk RNA sequencing datasets were used to evaluate the correlation between ISG expression in monocytes and PB, with a particular focus on monocyte expression of IFI27. An iceberg plot of bulk transcriptome data was used to identify genes that were predominantly expressed by monocytes in PB. DIRECT LS-TA RBBs of the three genes (IFI27, IFI44L and SIGLEC1) were evaluated by group-wise comparison, receiver operating characteristic and meta-analysis. In addition, the conventional interferon (IFN) score was evaluated for comparison of diagnostic performance. In viral infection datasets, DIRECT LS-TA of IFI27 (IFI27/PSAP or IFI27/CTSS) was most intensely activated (p value by t test <1e-9) and had the best area under the curve (0.94) among the three potential monocyte ISGs analysed. DIRECT LS-TA SIGLEC1 was also another monocyte biomarker but showed a lower activation (p<9e-5). IFI27/PSAP showed better diagnostic performance than the conventional IFN score. On the other hand, IFI44L was not a predominant monocyte expression gene. DIRECT LS-TA of IFI27 (IFI27/PSAP or IFI27/CTSS) measured in PB was the best biomarker of viral infection and IFN activation among ISGs predominantly expressed by monocytes. It performed even better than the conventional IFN score which required quantification of eight genes. The results suggest that DIRECT LS-TA of IFI27 is a monocyte-informative biomarker which is easy to determine in PB without the need for cell sorting.
Legionnaires' disease (LD) is a severe pneumonia caused by Legionella species., with Legionella pneumophila serogroup 1 (SG1) responsible for 70-80% of cases in Europe and the United States. In parts of Asia and the Western Pacific, Legionella longbeachae is also a common cause. Most urinary antigen tests (UATs) target only L. pneumophila SG1, limiting detection of other species. We evaluated the performance of five UATs: BinaxNOW immunochromatographic test (ICT), Sofia FIA, STANDARD F FIA, ImmuView and LIAISON, against the Binax enzyme immunoassay, with culture and polymerase chain reaction (PCR) used where available to confirm the infecting Legionella species. A total of 81 urine samples were tested across all assays, except STANDARD F (n=80). BinaxNOW ICT had the highest sensitivity for L. pneumophila SG1 with 100% specificity. ImmuView showed 100% sensitivity and specificity for L. longbeachae and 92.6% sensitivity for L. pneumophila SG1. In regions where L. longbeachae represents a substantial proportion of Legionella infections, the ImmuView assay offers an effective primary screening approach since it can simultaneously detect both L. pneumophila SG1 and L. longbeachae in a single test, thereby minimising reliance on slower diagnostic methods such as culture or PCR.
Placental assessment following a stillbirth is a crucial investigation. It helps identify possible causes or contributing factors to stillbirth. It can help evaluate the risk of recurrence in future pregnancies and may indicate whether further tests are needed. It also provides guidance for managing subsequent pregnancies. In this review, we discuss practical considerations in placental assessment following stillbirth, including how both pre-analytical and analytical factors can influence the assessment. We outline the changes that occur in the placenta after stillbirth and explain how to distinguish these changes from antemortem placental pathology known to cause stillbirth. In addition, we highlight incidental findings and artefacts in the placenta that can be confused with true pathology. Finally, we address current controversies, identify areas for future research, and propose a practical approach to assessing the placenta in cases of stillbirth.
