Criteria for the diagnosis of eggshell calcification:
(1) peripheral shell-like calcification <= 2 mm in thickness affecting >= 2 lymph nodes
(2) >= 1 lymph node >= 1 cm in diameter
(3) complete ring-like shadow in >= 1 lymph node (may be broken in the other nodes)
Additional calcifications may be present in the center of the lymph node.
Conditions associated with eggshell calcification of lymph nodes:
(1) coal workers pneumoconiosis (common)
(2) other forms of silicosis (common)
(3) deep fungal infection (histoplasmosis, blastomycosis)
(4) sarcoidosis
(5) post-radiation change in Hodgkin’s disease
(6) amyloidosis
Differential diagnosis:
(1) cross-section of bronchus
(2) atherosclerosis of aorta
(3) thymic cyst
(4) parathyroid or thyroid tumor
(5) pulmonary artery in pulmonary hypertension
