Thymic carcinoma presenting as cardiac tamponade.

To the Editor: Thymic carcinoma is a rare malignancy of the thymus gland accounting for less than 0.06% of thymic neoplasms. As opposed to the more common and relatively benign thymoma, it is characterized by an aggressive course and a poor prognosis. (1) We describe a case of lymphoepithelioma-like thymic carcinoma that presented in association with cardiac tamponade, which, to our knowledge, has not been reported in the literature before.

A 56-year-old white man presented with worsening dyspnea and vague chest discomfort of 1 month's duration. The physical examination revealed a thin, wasted man in moderate respiratory distress. His vital signs were temperature 97.2[degrees]F, blood pressure 110/74 mm Hg, pulse rate 110 beats/min, and respiratory rate 28 breaths/min. He had marked elevation of jugular venous pressure and bilateral lower-extremity edema. The ECG obtained at admission showed low-voltage QRS complexes. A transthoracic echocardiogram confirmed the presence of massive pericardial effusion. A computed tomographic scan of the thorax showed large pericardial and bilateral pleural effusions with a large necrotic anterior mediastinal mass infiltrating the pericardium. A decision was made to proceed with operative drainage of pericardial effusion with pericardial biopsy. In the operating room, just before the planned procedure, the patient decompensated and developed clinical cardiac tamponade, becoming markedly tachypneic and tachycardiac. He developed pulsus paradoxus and Kussmaul's sign. Central venous pressure was markedly elevated at 45 cm. The patient improved dramatically after an emergent subxiphoid pericardiotomy. The histopathologic report of the biopsy specimen revealed the presence of lymphoepithelioma-like thymic carcinoma. The patient died 11 months later after showing an initial partial response to multiagent chemotherapy.

Thymic carcinoma is an entity distinct from the more common and relatively less aggressive thymoma. Aggressive local and metastatic spread and poor response to treatment characterize it. Most commonly, patients with thymic carcinoma present with symptoms directly attributable to their anterior mediastinal mass (ie, chest pain, dyspnea, cough, dysphagia, superior vena cava obstruction). (2)

This report describes a unique initial presentation of lymphoepithelioma-like thymic carcinoma that, to our knowledge, has not been reported previously. The treatment of thymic carcinoma involves a multimodality approach that includes surgical resection, postoperative radiotherapy, and chemotherapy. Complete surgical resection is seldom possible. There is a tendency toward improved survival with postoperative radiotherapy. Chemotherapy is commonly used, but no significant beneficial effect has been documented. (3)

It should be emphasized that the definition of cardiac tamponade is clinical, and although echocardiography is the noninvasive diagnostic test of choice, overreliance on the echocardiographic signs of right atrial collapse and right ventricular diastolic collapse can be misleading. (4) Both false-positive and false-negative cases have been well described in the literature.

The presentation of malignancy with cardiac tamponade seems to be uncommon. A study found 73 such cases reported in the medical literature during a 60-year period. (5) Delay in diagnosis of cardiac tamponade--even in the face of typical features--has been a consistent feature in reported cases. Malignancy should be considered in the differential diagnosis of unexplained cardiac tamponade. Tamponade may present insidiously in patients with large pericardial effusions, and close observation of such patients is recommended.

References

(1.) Suster S, Rosai J. Thymic carcinoma: A clinicopathologic study of 60 cases. Cancer 1991;67:1025-1032.

(2.) Chung DA. Thymic carcinoma: Analysis of nineteen clinicopathological studies. Thorac Cardiovasc Surg 2000;48:114-119.

(3.) Ogawa K, Toita T, Uno T, et al. Treatment and prognosis of thymic carcinoma: Retrospective analysis of 40 cases. Cancer 2002; 94(12): 3115-3119

(4.) Fowler NO. Cardiac tamponade: A clinical or an echocardiographic diagnosis? Circulation 1993;87:1738-1741.

(5.) Muir KW, Rodger JC. Cardiac tamponade as the initial presentation of malignancy: Is it as rare as previously supposed? Postgrad Med J 1994;70:703-707.

Abid Yaqub, MD

Nancy J. Munn, MD, FCCP

Division of Pulmonary Medicine

Department of Medicine

Rebecca S. Wolfer, MD, FACS, FCCP

Division of Thoracic Surgery

Department of Surgery

Joan C Edwards School of Medicine

Marshall University

Veterans Affairs Medical Center

Huntington, WV