Based on the findings, the patient was diagnosed with sarcoidosis. A brief course of steroids significantly improved her symptoms.
This case is of interest as it illustrates how sarcoidosis may not always present with classic hilar lymphadenopathy and may require a careful review of chest x-ray to screen for subtle clues of this condition, if clinical suspicion for sarcoidosis remains high.
The doughnut sign on a lateral chest x-ray represents a radiopaque ring. It is bordered by enlarged lymph nodes at hilar and subcarinal region, located around intermedius bronchus, and normal profiles of right and left pulmonary arteries and aortic arch anteriorly and superiorly. This radiopaque ring resembles the appearance of a doughnut. A fullness in the lymph nodes may indicate lymphadenopathy and would warrant further investigation.
Chiarenza A, Esposto Ultimo L, Falsaperla D, et al. Chest imaging using signs, symbols, and naturalistic images: a practical guide for radiologists and non-radiologists. Insights into Imaging. 2019;10(114). doi:10.1186/s13244-019-0789-4