Bochdalek flower basket sign

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A 62-year-old male patient complained of recurrent headaches for one month. On routine computed tomography imaging, linear calcification was noted in the fourth ventricle extending laterally into foramen of Luschka, described radiological as Bochdalek flower basket sign [Figure 1a-c].

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Figure 1:

(a) Axial computed tomography of brain, (b) maximum intensity projection computed tomography, (c) schematic diagram of fourth ventricle choroid plexus demonstrating the classical flower basket appearance (black arrows), the medial vertical segment of the choroid plexus (open arrows), and horizontal segment of choroid plexus (arrow heads) that project into foramen of Luschka.

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Bochdalek flower basket sign is an eponymous word described by Vincent Bochdalek, a Czech anatomist, for protruded fourth ventricle choroid plexus through foramen of Luschka into cerebellopontine-cistern. Calcification of fourth ventricle choroid plexus is noted in 8% of patients aged about 60. However, complete calcification with a typical flower basket appearance is rare.

Developmentally fourth ventricle choroid plexus is composed of two inverted L-shaped structures. Two vertical limbs on each side of the midline extend into foramen of Magendie. Two transverse limbs extend laterally through foramen of Luschka and reach cerebellopontine fissures. These terminal parts of lateral segments protruding through foramen of Luschka have been named Bochdalek’s flower basket.^[1] It is essential radiologically to recognize the entity, as it could be misdiagnosed as a subarachnoid hemorrhage or vertebral artery/posterior inferior cerebellar artery aneurysm or even bilateral choroid plexus lymphomas.^[2]