Panse, Prasad M.

An accurate differential diagnosis for diffuse lung disease can be confidently established by using a systematic approach to identify the predominant radiographic pattern, determine the distribution of disease, and assess for architectural or volume change.

Interlobular septal thickening (ILST) is a feature on chest computed tomography (CT) that is characterized by abnormal widening of the interlobular septa, which are thin connective tissues that separate secondary pulmonary lobules within the lung parenchyma. They contain pulmonary venules and lymphatic vessels. On CT, these septa are normally not visible in healthy patients. However, various pulmonary pathologic conditions can lead to ILST. If present, ILST can be categorized into 3 different patterns based on its morphologic appearance: smooth, nodular, and irregular/fibrotic. Each pattern occurs from different disease processes with little overlap. In this pictorial essay, we review common and rare etiologies for each type of ILST. For each disease, we discuss relevant pathophysiology, epidemiology, risk factors, symptoms, physical exam findings, labs, and management. Subsequently, we present the ILST features along with the distribution (eg, unilateral, bilateral, central, peripheral) and ancillary imaging findings that can support the diagnosis. Finally, characteristic and high-resolution figures are presented.

This essay describes diagnostic criteria for and thoracic imaging appearances of acute and chronic coccidioidal pneumonia, unusual disease manifestations, and disseminated disease appearances.

Abstract Erdheim-Chester disease (ECD) and Langerhans cell histiocytosis (LCH) are two rare diseases typically separated by clinical, radiologic, and histologic criteria. However, coexistence of both entities is rare, with fewer than 50 cases reported. Although there are reports of patients with LCH and ECD in the same organ, there have been no reported cases of the two diseases involving the lung. We report two cases of ECD-LCH “overlap syndrome” occurring in the lung. In both cases, the diagnoses were supported by typical immunohistochemical patterns, and in both cases, the BRAF V600E mutation was identified by next-generation sequencing and confirmed by droplet digital polymerase chain reaction. In neither case was either diagnosis suspected. The recognition of overlap histiocytoses is important. Although LCH and ECD may differ in treatment and prognosis, in some cases, such as the two patients reported here, they may have the same activating mutations and may be able to be treated with the same targeted therapy.

Abstract Introduction Atrial fibrillation (AF) is the most common arrhythmia worldwide. The role of the pulmonary veins (PV) in its' pathogenesis has been well described, as have the most frequently seen anatomical variants of these veins. Prior studies have shown conflicting evidence on the potential association of PV variants and incidence of AF. We sought to reassess this association. Methods We conducted a retrospective case-control study of patients with AF (cases) and without AF (control group) undergoing cardiac CT imaging. We documented patient characteristics and cardiac anatomical features including PV variants, LV ejection fraction (EF) and left atrial (LA) volume/diameter. Results 295 patients were included: 194 with AF and 101 without. 71% of AF cases were male. We showed a numerical difference for PV variants between the AF and control group that was not statistically significant (48.5% and 39.6%, p=0.15). The overall incidence of PV variants was higher than in previous studies. A significant association was identified between left atrial appendage (LAA) morphology and incidence of AF. Conclusion The suggested association between PV anatomical variants and the pathogenesis of AF may not be as clear-cut as previously thought. Our study is one of the largest of its kind and provides conflicting evidence with prior studies in this area. An improved understanding of the complex pathophysiology of AF and its relation to the pulmonary veins may help to guide future preventative and therapeutic strategies. Funding Acknowledgement Type of funding sources: None.

ObjectivesLeft ventricular (LV) septal hypertrophy in aortic stenosis raises diagnostic and therapeutic questions. However, the etiology and clinical consequences of this finding have not been well studied. The aim of this study was to perform a morphologic evaluation of the LV in aortic stenosis and to investigate the contributing factors and consequences of septal hypertrophy.MethodsPatients with moderate or severe aortic stenosis were prospectively enrolled. Patients with previous myocardial infarction, wall motion abnormalities, at least moderate valvular regurgitation, known cardiomyopathy, an LV ejection fraction of less than 50%, and age younger than 65 years were excluded.ResultsForty‐one patients underwent a final analysis. Septal hypertrophy (LV septal wall thickness ≥15 mm) was confirmed in 21 of 41 patients. The septal hypertrophy group had higher peak aortic valve velocity, a higher diabetes mellitus rate, and a higher rate and longer duration of hypertension than those without septal hypertrophy. The peak aortic valve velocity (odds ratio, 7.1; 95% confidence interval, 1.4–37.1) and diabetes mellitus (odds ratio, 7.4; 95% confidence interval, 1.2–46.2) were the significant factors associated with septal hypertrophy by multivariate analysis. Intraventricular conduction disturbance on electrocardiography was more frequent in the septal hypertrophy group (P = .021).ConclusionsLeft ventricular septal hypertrophy was commonly observed in elderly patients with aortic stenosis, and a higher aortic valve velocity, hypertension, and diabetes mellitus were associated factors. Intraventricular conduction disturbance occurred more often in patients with septal hypertrophy than those without, which implies the pathophysiologic consequence. Further studies are needed to determine the impact of septal hypertrophy and intraventricular conduction disturbance on the prognosis of patients after aortic valve interventions.