Caseous Mitral Annular Calcification

Case Study: Caseous Mitral Annular Calcification

Introduction

Caseous mitral annular calcification is considered to be a rare and incidental echocardiographic finding with no ‘mass-related events’ detected by Harpaz et al. They describe diagnosis of caseous calcification had little impact on patient symptoms and morbidity. In this case study however, extrusion of the caseous mass was associated with an episode of acute pulmonary oedema with new significant mitral regurgitation.

Caseous calcification of the mitral annulus has been reported as an uncommon variation of mitral annular calcification. Described previously in the literature as a soft, periannular extensive calcification, it can be readily picked up on both transthoracic and transoesophageal echo. Commonly misdiagnosed on echocardiography as a tumour or myocardial abscess in cases where cardiotomy has been performed, the entity has been discovered to contain a mixture of calcium, fatty acids and cholesterol with a toothpaste like texture.

Transthoracic echocardiography cases describe a large round mass sometimes with central echolucencies, situated in the posterior mitral annulus. Concluding that this impressive lesion appeared to carry a benign prognosis, conservative treatment was recommended. When the patient presented with acute pulmonary oedema, serial echocardiograms described an undocumented finding.

Case Report:

An 82y.o asymptomatic female presented to our clinic for assessment of a suspected left atrial mass. First detected on routine transthoracic echo five years earlier, assessment of any progression in mass morphology was requested.

Transthoracic echocardiography revealed a large homogenous circumscribed and echo dense mass arising from the posterior mitral annulus. The mass was well demarcated with mitral chordal attachment, suggesting incorporation and replacement of the posterior mitral leaflet. The mass was measured from 2D echocardiography as 2.9 x 2.2 x 3.5cm. Other echocardiographic findings included normal left ventricular function (EF 55%) with moderate left ventricular hypertrophy (LV mass index 139gm/m2). Mild pulmonary hypertension (PASP 44mmHg) centrally directed mitral regurgitation and normal left atrial volume were also recorded (20cc/m2).

The mass was identified as severe posterior mitral annular calcification and referred back to the patients local doctor. No intervention was deemed necessary.
Three weeks later the patient presented to the emergency centre of a major public hospital with shortness of breath. Echocardiography showed the mitral annular mass was now an echodense sclerotic capsule with echolucent interior. A mobile echodensity was observed on the posterior leaflet which was determined unlikely to be chordal rupture or a flail mitral leaflet.

The left ventricular function was normal and the pulmonary artery pressure was 70mmHg. There was also a dilated left atrium and severe mitral regurgitation. The patient developed pulmonary oedema which settled after treatment with oxygen and Frusimide. Repeated blood cultures were negative as were all other stigmata for infective endocarditis.

Discussion

Caseous mitral annular calcification has been defined in a rare subgroup of patients that is yet to be widely recognised nor described by echocardiographers.
The diagnosis of caseous mitral annular calcification is difficult based on patient clinical symptoms due to the lack of correlation between its presence and clinical findings. Incidence in the general population has been reported as very low but until this classification is more widely recognised and reported, its true incidence is uncertain.

Echocardiography immediately following the development of acute pulmonary oedema showed the development of significant mitral regurgitation. The predominantly anteriorly directed jet with broad spray pattern suggested an acute event involving the posterior mitral valve leaflet and its support structures. The discovery of the small mobile echodensity attached to the posterior annular mass following patient symptoms was another interesting development detected on the transthoracic echocardiogram. Its appearance was not suggestive of a flail mitral leaflet nor a ruptured chordae tendinae. Initially it was thought likely to be a vegetation, however all other indications of infective endocarditis were absent. Hence it was proposed that this mobile echodensity may represent part of the ruptured capsule of the mitral annular mass. Further echocardiogram studies showed no significant change over time.

Transthoracic echo has proved a good tool for diagnosing caseous calcification of the mitral annulus and its delineation from more common mitral annular calcification. In diagnosed cases where transoesophageal echocardiography has been undertaken for further entity assessment, results determined that transoesophageal echo produced clearer images of the structure and the central liquefaction, but did not provide significant additional information to influence in patient treatment.


Figure 1 - Pre-rupture, Parasternal Long Axis View

Figure 1 - Pre-rupture, Parasternal Long Axis View

Figure 2 - Pre-rupture, Parasternal Long Axis View

Figure 2 - Pre-rupture, Parasternal Long Axis View

Figure 3 - Post, Parasternal Long Axis View

Figure 3 - Post, Parasternal Long Axis View

Figure 4: Post, Parasternal Long Axis View

Figure 4: Post, Parasternal Long Axis View


References

  1. Harpaz D, Auerbach I, Vered Z, Motro M, Tobar A, Rosenblatt S. Caseous calcification of the mitral annulus: A neglected, unrecognised diagnosis. J Am Soc Echocardiogr 2001;14:825-31.
  2. Teja k, Gibson RS, Nolan SP. Atrial extension of mitral annular calcification mimicking intracardiac tumor Clin Cardiol 1987;10:546-8.
  3. Borowski A, Korb H, Voth E, de Vivie ER. Asymptomatic myocardial abscess. Thorac Cardiovasc Surg 1988;36:338-40.
  4. Gilbert HM, Grodman R, Chung MH, Hartman G, Krieger KH, Hartman BJ. Sterile, caseous mitral valve “abscess” mimicking infective endocarditis. Clin Infect Dis 1997;24:1015-6.
  5. Kautzner J, Vondracek V, Jirasek A, Belohlavek M. Tumor-like mitral annular calcification with central liquefaction. Echocardiography 1993;10:459-63.
  6. Pomerance A. Pathological and clinical study of calcification of the mitral valve ring. J Clin Pathol 1970;23:354-61
  7. Kronzon I, Winer HE, Cohen ML. Sterile, caseous mitral annular abscess. J am Coll Cardiol 1983;2:186-90

 

Author:

Narelle Cranston Adams
Senior Echocardiographer
CardioVascular Services
Perth, WA
Australia

 

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