Complications of fibrotic interstitial lung disease for the general radiologist

Interstitial lung diseases (ILDs) are a heterogeneous group of conditions characterised by non-infective inflammation and scarring of the lung parenchyma. They are not infrequently encountered by the general radiologist in both acute and outpatient reporting settings who may even be the first to make the diagnosis. In the acute setting, patients with ILD can present with respiratory deterioration due to a number of causes and in addition to the common causes of dyspnoea, an acute exacerbation of ILD needs to be considered. An exacerbation can be initiated by common triggers such as infection, pulmonary embolism (PE), and heart failure, and it can also be initiated by an insult to the lung or occur due to an unknown cause. Particular care needs to be taken when interpreting computed tomography (CT) examinations in these patients as the findings of an acute exacerbation are non-specific and patient and technical factors can cause spurious appearances including dependent changes, breathing artefact and contrast medium opacification. In the non-acute setting, patients with ILD are at increased risk of lung cancer and pulmonary hypertension (PH), with lung cancer being a particularly important consideration as treatments carry the risk of triggering an acute exacerbation or deterioration in lung function. Overall, this review aims to provide an overview for the general radiologist of additional factors to consider when interpreting scans in patients with ILD and how the presence of ILD impacts the differential diagnoses and complications that can occur in these patients in both acute and non-acute settings.

Clinical, genetic, and pathologic characterization of FKRP Mexican founder mutation c.1387A>G

Objective

To characterize the clinical phenotype, genetic origin, and muscle pathology of patients with the FKRP c.1387A>G mutation.

Methods

Standardized clinical data were collected for all patients known to the authors with c.1387A>G mutations in FKRP. Muscle biopsies were reviewed and used for histopathology, immunostaining, Western blotting, and DNA extraction. Genetic analysis was performed on extracted DNA.

Results

We report the clinical phenotypes of 6 patients homozygous for the c.1387A>G mutation in FKRP. Onset of symptoms was <2 years, and 5 of the 6 patients never learned to walk. Brain MRIs were normal. Cognition was normal to mildly impaired. Microarray analysis of 5 homozygous FKRP c.1387A>G patients revealed a 500-kb region of shared homozygosity at 19q13.32, including FKRP. All 4 muscle biopsies available for review showed end-stage dystrophic pathology, near absence of glycosylated α-dystroglycan (α-DG) by immunofluorescence, and reduced molecular weight of α-DG compared with controls and patients with homozygous FKRP c.826C>A limb-girdle muscular dystrophy.

Conclusions

The clinical features and muscle pathology in these newly reported patients homozygous for FKRP c.1387A>G confirm that this mutation causes congenital muscular dystrophy. The clinical severity might be explained by the greater reduction in α-DG glycosylation compared with that seen with the c.826C>A mutation. The shared region of homozygosity at 19q13.32 indicates that FKRP c.1387A>G is a founder mutation with an estimated age of 60 generations (∼1,200–1,500 years).

Endogenous Pulmonary Antibiotics

The human lung produces a variety of peptides and proteins which have intrinsic antimicrobial activity. In general these molecules have broad spectra of antimicrobial activity, kill micro-organisms rapidly, and evade resistance generated by pathogens. In recent years it has become increasingly apparent that the antimicrobial peptides (AMPs) simultaneously possess immunomodulatory functions, suggesting complex roles for these molecules in regulating the clearance of, and immune response to, invading pathogens. These collective properties have stimulated considerable interest in the potential clinical application of endogenous AMPs.

This article outlines the biology of AMPs, their pattern of expression in the lung, and their functions, with reference to both antimicrobial and immunomodulatory activity. We then consider the biological importance of AMPs, before concentrating on the potential to use AMPs to therapeutic effect. The principles discussed in the article apply to innate immune defence throughout the body, but particular emphasis is placed on AMPs in the lung and the potential application to pulmonary infection.

TPM3 deletions cause a hypercontractile congenital muscle stiffness phenotype

OBJECTIVE

Mutations in TPM3, encoding Tpm3.12, cause a clinically and histopathologically diverse group of myopathies characterized by muscle weakness. We report two patients with novel de novo Tpm3.12 single glutamic acid deletions at positions ΔE218 and ΔE224, resulting in a significant hypercontractile phenotype with congenital muscle stiffness, rather than weakness, and respiratory failure in one patient.

METHODS

The effect of the Tpm3.12 deletions on the contractile properties in dissected patient myofibers was measured. We used quantitative in vitro motility assay to measure Ca(2+) sensitivity of thin filaments reconstituted with recombinant Tpm3.12 ΔE218 and ΔE224.

RESULTS

Contractility studies on permeabilized myofibers demonstrated reduced maximal active tension from both patients with increased Ca(2+) sensitivity and altered cross-bridge cycling kinetics in ΔE224 fibers. In vitro motility studies showed a two-fold increase in Ca(2+) sensitivity of the fraction of filaments motile and the filament sliding velocity concentrations for both mutations.

INTERPRETATION

These data indicate that Tpm3.12 deletions ΔE218 and ΔE224 result in increased Ca(2+) sensitivity of the troponin-tropomyosin complex, resulting in abnormally active interaction of the actin and myosin complex. Both mutations are located in the charged motifs of the actin-binding residues of tropomyosin 3, thus disrupting the electrostatic interactions that facilitate accurate tropomyosin binding with actin necessary to prevent the on-state. The mutations destabilize the off-state and result in excessively sensitized excitation-contraction coupling of the contractile apparatus. This work expands the phenotypic spectrum of TPM3-related disease and provides insights into the pathophysiological mechanisms of the actin-tropomyosin complex.

Endobronchial ultrasound-guided fine-needle aspiration and liquid-based thin-layer cytology

BACKGROUND

Optimal management of patients with lung cancer requires accurate cell typing of tumours and staging at the time of diagnosis. Endobronchial ultrasound-guided lymph node aspiration as a method of diagnosing and staging lung cancer is a relatively new technique.

AIM

To report the use of liquid-based-thin-layer cytology for the processing and reporting of these specimens.

METHODS

The specimens obtained from 80 patients were processed using the ThinPrep system, with the remainder of the samples being processed as a cell block.

RESULTS

40 of the 81 procedures yielded malignant cells (30 non-small cell carcinoma, 8 small-cell carcinoma and 2 combined small-cell carcinoma/non-small-cell carcinoma). The cell blocks were found to contain sufficient material to allow the immunohistochemical characterisation of tumour cells with a range of antibodies.

CONCLUSION

The use of liquid-based-thin-layer cytological techniques provides high-quality specimens for diagnostic purposes. When used in conjunction with cell blocks, sufficient material may be obtained to allow immunohistochemical studies to confirm the tumour cell type. Given the current move towards centralisation of pathology services, this approach gives the pathologist high-quality specimens without the need for direct onsite support at the time of the procedure.