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Rationale: Chronic cough is characterized by frequent urges to cough and a heightened sensitivity to inhaled irritants. Airway sensory nerves trigger cough. We hypothesized that sensory nerve density is increased in chronic cough, which may contribute to excessive and persistent coughing. Objectives: To measure airway nerve density (axonal length) and complexity (nerve branching, neuropeptide expression) in humans with and without chronic cough. Methods: Bronchoscopic human airway biopsies were immunolabeled for nerves and the sensory neuropeptide substance P. Eosinophil peroxidase was also quantified given previous reports showing associations between eosinophils and nerve density. Three-dimensional image z-stacks of epithelium and subepithelium were generated using confocal microscopy, and from these z-stacks, total nerve length, the number of nerve branch points, substance P expression, and eosinophil peroxidase were quantified within each airway compartment. Measurements and Main Results: Nerve length and the number of branch points were significantly increased in epithelium, but not subepithelium, in chronic cough compared with healthy airways. Substance P expression was scarce and was similar in chronic cough and healthy airways. Nerve length and branching were not associated with eosinophil peroxidase nor with demographics such as age and sex in either group. Conclusions: Airway epithelial sensory nerve density is increased in chronic cough, suggesting sensory neuroplasticity contributes to cough hypersensitivity.

Case Presentation A 44-year-old man presented to the ED with acute massive hemoptysis and hypoxia. His history was notable for 1 year of progressively worsening shortness of breath at both rest and with exertion. He denied chest discomfort and endorsed near syncope while driving in recent months. He recently had been treated with antibiotics for two episodes of presumed pneumonia, based on right lower lobe opacification on chest radiography.

A fever of unknown origin is often pursued diagnostically under the framework of infectious, rheumatologic, and neoplastic causes. When encephalopathy ensues, the differential diagnosis narrows, but can remain elusive, particularly when dealing with rare diseases. We present the case of a patient with fever of unknown origin and intermittent encephalopathy that spanned multiple hospital admissions and ultimately yielded a diagnosis of intravascular large B cell lymphoma complicated by hemophagocytic lymphohistiocytosis. We review the varying presentations of this disease, when to consider this as a diagnosis, and how to most accurately make the diagnosis.