A labourer presented with chronic cough. X-ray shows "egg shell" calcification in hilar nodes which are diagnostic of:

Very early silicosis may be seen only on CT, although in the later stages of the process, the small nodules and conglomerate masses are readily seen on either conventional radiographs or CT images. Hilar and mediastinal lymph nodes may calcify in the periphery of the lymph node, a type of calcification known as eggshell calcification. An acute form of silicosis radiographically resembles pulmonary edema. Ref: Chiles C., Gulla S.M. (2011). Chapter 4. Radiology of the Chest. In M.Y. Chen, T.L. Pope, D.J. Ott (Eds), Basic Radiology, 2e.