Ann Thorac Surg 1998;66:952-954
© 1998 The Society of Thoracic Surgeons
Case Reports
Tophaceous pseudogout of the mitral valve
Marc R. Moon, MDa,
James I. Fann, MDa,
Prakash C. Deedwania, MDb,
Rollington Ferguson, MDb,
Jon C. Kosek, MDc,
Thomas A. Burdon, MDa
a Division of Cardiothoracic Surgery, Veterans Affairs Health Care System, Palo Alto, California, USA
b Division of Cardiology, Veterans Affairs Health Care System, Palo Alto, California, USA
c Department of Pathology, Veterans Affairs Health Care System, Palo Alto and Fresno, California, USA
Accepted for publication April 6, 1998.
Address reprint requests to Dr Moon, Department of Cardiothoracic Surgery, Washington University, St. Louis, MO 63110-1013
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Abstract
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This report describes a 61-year-old patient on chronic hemodialysis with multiple, left-sided, intracardiac masses causing intermittent coronary obstruction. Mitral valve replacement was performed. Massive deposition of calcium pyrophosphate crystals in and around the valve cusps led to the diagnosis of tophaceous pseudogout (tumoral calcinosis) of the mitral valve.
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Introduction
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Tophaceous pseudogout or tumoral calcinosis is a rare disorder characterized by hyperphosphatemia and normocalcemia with extensive soft-tissue deposition of calcium pyrophosphate crystals [1, 2]. Although the etiology remains unknown, the incidence appears to be greater in patients with chronic renal failure and secondary hyperparathyroidism [1]. The lesions of tumoral calcinosis are typically slow-growing, nontender nodules adjacent to large joints (hips, elbows, shoulders); they remain asymptomatic until progressive enlargement impinges on normal articular function. Visceral calcium deposition is common in patients with chronic renal failure [3, 4]; here we describe intracardiac tumoral calcinosis.
A 61-year-old man presented with intermittent, substernal chest pain that was unresponsive to sublingual nitroglycerin and would resolve spontaneously. For 10 years, the patient had been on hemodialysis for chronic renal failure due to hypertension and diabetes. The patient denied fever, chills, or history of exertional chest pain. Physical examination revealed a soft systolic murmur at the left sternal border. Electrocardiogram demonstrated first-degree heart block but no ischemic changes. Transesophageal echocardiography revealed a thickened, calcified mitral valve with mild mitral regurgitation and normal left ventricular function; the left atrium was mildly enlarged. Three dense, calcified, intracavitary masses were visualized: one mobile, pedunculated mass on the atrial surface of the anterior mitral leaflet (1.2 x 1.0 cm) and two masses in the left ventricular outflow tract at the junction between the mitral valve and the noncoronary cusp of the aortic valve (1.3 x 1.0 cm mobile, pedunculated; 0.8 x 0.8 cm sessile) (Fig 1). Laboratory data included a white blood cell count of 7,700/µL, calcium level of 9.5 mg/dL (normal, 8.5 to 10.5 mg/dL), phosphorus level of 8.3 mg/dL (normal, 2.3 to 4.7 mg/dL), calcium-phosphorus product of 78.9 mg/dL2 (normal, 25 to 45 mg/dL2), and a parathyroid hormone level of 400 pg/mL (normal, 10 to 65 pg/mL). Cardiac catheterization revealed normal coronary anatomy without atherosclerotic changes. The differential diagnosis included vegetations, tumor, and thrombus with coronary embolization. Operation was performed for diagnosis and debridement or excision of these masses.
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Fig 1. Transesophageal echocardiography demonstrated multiple distinct intracardiac masses. In this long-axis view, masses are clearly visualized in the left ventricular outflow tract (large arrow) and on the atrial surface of the anterior mitral valve leaflet (small arrow).
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Inspection through the aortic valve revealed two white, calcified, friable, chalky masses abutting the ventricular surface of the anterior mitral leaflet. One mass (1.3 x 1.0 cm) was attached to the leaflet by a short stalk; the other was more sessile and could not be removed intact. Inspection through a longitudinal left atriotomy revealed a similar mass on the atrial surface of the anterior mitral leaflet and extensive calcification of the posterior annulus; the anterior annulus was relatively spared. After excision of the valve and subvalvular apparatus and debridement of the posterior annulus, mitral valve replacement was performed with a 29-mm bileaflet mechanical valve (St. Jude Medical, Minneapolis, MN) to avoid early calcification of a bioprosthetic valve.
Microscopic examination revealed dense, cell-poor, fibrous tissue and extensively crystallized, calcific material occasionally surrounded by a few multinucleated macrophages without evidence of active infection, microorganisms, or thrombi. Polarized light microscopy demonstrated that the heavily calcified material was weakly positively birefringent, characteristic of calcium pyrophosphate deposition (tophaceous pseudogout) (Fig 2).
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Fig 2. Weakly positive birefringent calcium pyrophosphate dihydrate crystal deposits admixed with cell-poor, dense fibrous tissue and rare inflammatory cells. (Hemotoxylin and eosin stain; x200 before 47% reduction.)
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After correction of a postoperative coagulopathy, the patient was discharged home in good health. Transthoracic echocardiography at 6 weeks demonstrated a well-seated prosthesis, no perivalvular leak, and absence of the previously visualized perivalvular masses. The patient is currently free of cardiac symptoms 1 year postoperatively.
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Comment
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Extraosseus calcium deposition has been described in various visceral organs including the lungs, kidneys, and heart of dialyzed uremic and hypercalcemic patients [3, 4]. Metastatic myocardial calcification is present in up to 50% of patients on chronic dialysis, causing a rhythm or contractile disturbance in approximately half of these patients. Terman and colleagues [3] presented a series of 6 patients on dialysis with parathyroid hyperplasia and metastatic myocardial calcification. Calcium deposition with fibrosis of the atrioventricular node or interventricular septum led to partial or complete heart block with an interventricular conduction defect in two thirds of the patients; congestive heart failure also occurred in patients with extensive calcification of the left ventricular myocardium. In all cases, calcium deposition was confined to the myocardial tissue. Tophaceous gout of the mitral valve with urate crystal deposition has been described in patients with a long-standing history of extracardiac gout; however, the nodules have been small, clinically insignificant, and only incidentally discovered during autopsy or open cardiac operations [5, 6]. A recent report from the Mayo Clinic [7] described 11 cases of calcified amorphous tumors of the heart encountered during a 30-year period; none of these cases were associated with chronic renal failure, suggesting azotemic pseudogout is a rare cause of calcified cardiac tumors.
Calcium pyrophosphate deposition disease includes a broad spectrum of clinical manifestations associated with calcium pyrophosphate crystals [1, 2]. Tophaceous pseudogout is a rare clinical form of calcium pyrophosphate deposition characterized by tumoral or massive growth (tumoral calcinosis) in large joints, often after repetitive trauma. Some lesions are surrounded by a pseudocapsule, whereas others extend fingerlike projections into surrounding tissues. Tophaceous pseudogout can be differentiated from tophaceous gout by the identification of weakly positive birefringent calcium pyrophosphate crystals instead of strongly negative monosodium urate crystals. Primary idiopathic tumoral calcinosis is a heritable error in phosphorus metabolism, which leads to extracellular deposition of calcium hydroxyapatite crystals in periarticular soft tissue masses [8]; secondary tumoral calcinosis occurs in patients with chronic renal failure. The lesions of tumoral calcinosis are characterized as large, neoplastic-appearing granular masses that occur in older individuals, can involve visceral organs, and are associated with metabolic disorders producing hyperphosphatemia [1, 2]. A serum calcium-phosphorus product greater than 70 mg/dL2 in patients with secondary hyperparathyroidism will often produce soft tissue calcification and tumoral calcinosis [1]. Medical treatment of tumoral calcinosis, including phosphate depletion, will stop progression of the disease, but the calcium deposits rarely regress. Parathyroidectomy and renal transplantation can reduce soft tissue metastatic calcification in selected patients [1, 3]. Recurrence after incomplete excision is common in peripheral nodules; therefore, complete resection of the tumoral calcinosis lesions with mitral valve replacement was performed in our case.
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References
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- Terman D.S., Alfrey A.C., Hammond W.S., Donndelinger T., Ogden D.A., Holmes J.H. Cardiac calcification in uremia. A clinical, biochemical and pathologic study. Am J Med 1971;50:744-755.[Medline]
- Alfrey A.C., Solomons C.C., Ciricillo J., Miller N.L. Extraosseous calcification. Evidence for abnormal pyrophosphate metabolism in uremia. J Clin Invest 1976;57:692-699.
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Abstract
Introduction
