Sail and Spinnaker Sail Signs

‘There are numerous variations in structure and function, in posture and in the position of organs, which fall within natural limits, but have nevertheless been frequently misinterpreted as pathological findings.’ These words introduce the 1948 article by Kemp and colleagues ¹ that pointed out a sail-like appearance of the normal thymus (Figures 1 and 2). ‘The radiographs of a number of young children, in the Child Health Survey conducted by the Institute of Social Medicine at Oxford, show a sail-like triangular opacity projecting from the mediastinum, which investigation has proved to be the thymus gland.’ ¹ The sail sign was seen in 44 (8.8%) of 498 children examined at 6 months of age. None had pulmonary or cardiac symptoms. Three cases had autopsy proof. The authors credit Sir James Brailsford for being the first to suggest ‘that this shadow was the thymus.’ Figure 1 Chest radiograph with sail-like thymus. Reprinted from Kemp et al.<xref ref-type="bibr" rid="ref73_1"> ¹ </xref> A sail-like triangular projection from the mediastinum a radiographic appearance of the thymus gland. <italic>Br. J. Radiol.,</italic> 1948,21, 618–624, with permission of the British Institute of Radiology https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig73_1_B.jpg"/> Figure 2 Sloop with triangular sails. Photo courtesy of United States Navy https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003076568/34c29fd5-5662-4e8f-b58c-badd7fa5d724/content/fig73_2_B.jpg"/>