Histopathology
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There have been few reports on immunoglobulin-G4 (IgG4)-related interstitial pneumonia (IP), and its clinical features remain unclear. The objective of this study was to assess whether IP with marked IgG4-positive plasma cell infiltration without extrathoracic lesions of IgG4-related disease (RD) should be diagnosed as a subtype of IgG4-RD or a separate entity. ⋯ IP with marked IgG4-positive plasma cell infiltration without extrathoracic lesions of IgG4-RD had different pathological features from those of IgG4-RD, and it is appropriate to regard this as a separate entity.
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Pulmonary Langerhans cell histiocytosis (PLCH) is an idiopathic cigarette smoking-related disorder of the lung. Molecular changes in cellular or fibrotic stages of PLCH have not been investigated. We studied the prevalence of extracellular signal-regulated kinase (ERK) pathway mutations in different PLCH stages and other non-PLCH smoking-related lung diseases. ⋯ The presence of identical but mutually exclusive ERK pathway mutations in multi-focal PLCH supports a neoplastic/clonal origin for this disease. Patient age and mutation type differed between cellular and fibrotic histology and may indicate a natural progression or a mutation-specific pathogenicity.
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A new approach to the management of non-small-cell lung cancer (NSCLC) has recently emerged that works by manipulating the immune checkpoint controlled by programmed death receptor 1 (PD-1) and its ligand programmed death ligand 1 (PD-L1). Several drugs targeting PD-1 (pembrolizumab and nivolumab) or PD-L1 (atezolizumab, durvalumab, and avelumab) have been approved or are in the late stages of development. Inevitably, the introduction of these drugs will put pressure on healthcare systems, and there is a need to stratify patients to identify those who are most likely to benefit from such treatment. ⋯ Key factors to consider include the source and timing of sample collection, pre-analytical steps (sample tracking, fixation, tissue processing, sectioning, and tissue prioritization), analytical decisions (choice of biomarker assay/kit and automated staining platform, with verification of standardized assays or validation of laboratory-devised techniques, internal and external quality assurance, and audit), and reporting and interpretation of the results. This review addresses the need for integration of PD-L1 immunohistochemistry with other tests as part of locally agreed pathways and protocols. There remain areas of uncertainty, and guidance should be updated regularly as new information becomes available.
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The separation of fibrotic non-specific interstitial pneumonia (FNSIP) and usual interstitial pneumonia (UIP) is important for patient treatment and prognosis, but is sometimes a difficult diagnostic problem. Most authors believe that fibroblast foci are rare in NSIP, and that the finding of multiple fibroblast foci suggests a diagnosis of UIP. Similarly, architectural distortion is viewed as favouring a diagnosis of UIP. This study aims to assess these criteria for their diagnostic utility. ⋯ Otherwise typical FNSIP cases can show architectural distortion caused by confluence or marked expansion of fibrotic alveolar walls. These areas tend to be associated with fibroblast foci. These findings do not imply a poor prognosis, and should not be confused with UIP.
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Large B cell lymphomas with MYC and BCL6/3q27 rearrangements, designated MYC/BCL6 DHL, are uncommon. Our aim was to better characterize this group of tumours. ⋯ MYC/BCL6 DHL is an aggressive B cell lymphoma and patients often have an aggressive clinical course and poor prognosis, similar to patients with MYC/BCL2 DHL.