Blood cyst pathology
BCs of the cardiac valves are usually described as round or oval-shaped masses, either bluish or yellowish in colour, at times pedunculated and of variable sizes.
Mean maximum size of MV BCs was 20±8 mm, ranging from 3 to 46 mm; in 4 cases the cyst was considered as ‘giant’ despite a large variability of sizes7,9,26,32. The most frequent location of the cysts was the anterior mitral valve leaflet (AML) occurring in 33 cases, followed by the anterior papillary muscle in 8, the posterior mitral leaflet (PML) in 5 and the posterior papillary muscle in 4. The cyst was described to be attached to the chordae tendinae in one, to the mitral annulus in one and to an unspecified papillary muscle in one; in one patient with 2 BCs both AML and PML were involved14. In 3 patients 2 BC were found6,14,30. Some BCs have been described as multilobulated9,12,17,50.
The maximum size of TV BCs ranged from 18 to 33 mm (mean, 24±5 mm); in 3 cases the size of the BC was not indicated54,58,61. BCs were located on the septal TV leaflet in 4, anterior TV leaflet in 2 and the posterior TV leaflet in 1 case; in one patient location of the BC was not reported58.
The maximum size of the 3 PV BCs was 8, 30 and 40 mm, respectively; according to the authors’ description BCs were located on the posterior PV cusp in 1 case and on the right PV cusp in 1; in 1 case the location is not clearly indicated64.
Histology of the excised tissue has not been reported in all the surgical cases. When available histologic data, regardless of BC location, have been substantially uniform in describing the BC wall as composed mainly by fibrous tissue of various thickness (Fig. 2A), at times with a myxoid stroma. In many cases the inner BC wall was lined with typical endothelium while smooth calcific spots were occasionally seen19,49. The fibrous nature of the BC wall is also confirmed by immunohistochemistry (Fig. 2B). Interestingly, no ultrastructural images have been reported in BCs excised from cardiac valves of human beings.