Egg shell calcifiaction of the hilar nodes is seen in-
Eggshell calcification is a radiographic term describing abnormal hilar or mediastinal lymph nodes. According to Fraser and Pare, "Eggshell calcification is uncommon; it consists of a ring of calcification around the periphery of a lymph node and occurs most typically in silicosis. Ref Davidson 23rd edition pg 599
Asbestosis
Berylliosis
Silicosis
Coal worker's pneumoconiosis
Miscellaneous