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Thymic sail sign

Case contributed by Claire Isidro


Term newborn baby boy born via c-section due to fetal distress was transferred to the NICU for mild respiratory distress.

Patient Data

Age: Neonate
Gender: Male

A homogeneous soft tissue opacity in the right upper anterior and superior mediastinum extending laterally into the right upper lung zone consistent with a thymic sail sign is noted.

There is diffuse hyperinflation and mild pulmonary interstitial edema consistent with transient tachypnea of the newborn (TTN).

No pleural effusion or pneumothorax.

Case Discussion

The thymus is a lymphoid organ that undergoes variations in size and shape with age and disease. It consists of right and left lobes. As a primary lymphoid organ, it is where T cells mature. With age, the thymus grows rapidly and gradually involutes. In healthy children, it is at its greatest size in the first few years of life. Because of this, it can be visualized in chest radiographs of healthy children up to the age of 3 years with no pathological significance. 

Radiographically, it can be identified as a triangular-shaped opacity extending laterally from the right side of the mediastinum resembling a ship's sail. The thymus has no mass effect on adjacent structures. This normal finding should not be confused with a mass or lesion.

Also, we can see vessels through the thymic opacity and the thymus is bounded by the horizontal fissure seen as a thin horizontal line traversing through the right mid zone as in this case.

This case was submitted with supervision and input from:

Soni C Chawla, M.D.
Associate Professor
Department of Radiological Sciences
David Geffen School of Medicine at UCLA
Olive View - UCLA Medical Center

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Case information

rID: 76278
Published: 18th Apr 2020
Last edited: 18th Apr 2020
Inclusion in quiz mode: Included
Institution: David Geffen School of Medicine

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