Question

A $68$-year-old man presents to the clinic complaining of progressive shortness of breath on exertion and a dry cough that has slowly worsened over the past year. He denies any fever, chills, chest pain, or productive sputum. The patient worked as a pipefitter in a naval shipyard for $30$ years before retiring. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $130/80\text{ mm Hg}$, pulse is $78/\text{min}$, and respiratory rate is $18/\text{min}$. Physical examination reveals clubbing of the fingers and fine, dry end-inspiratory crackles at both lung bases. There is no jugular venous distension, and heart sounds are normal without murmurs. Laboratory studies show a normal complete blood count and a serum thyroid-stimulating hormone (TSH) level of $1.8\text{ }\mu\text{U/mL}$ (normal: $0.4-4.0\text{ }\mu\text{U/mL}$). A chest radiograph demonstrates bilateral reticulonodular interstitial opacities most prominent in the lower lobes, along with distinct calcified plaques on the diaphragmatic pleura. Which of the following is the most likely diagnosis?