Cardiac leiomyosarcoma

Last revised by Joachim Feger on 26 Dec 2021

Cardiac leiomyosarcomas are malignant smooth muscle tumors of the heart.

Cardiac leiomyosarcomas are rare primary malignant tumors of the heart accounting for less than one-fifth of cardiac sarcomas. They have been found in a wide age range from 6 months to 86 years with a mean age of 48 years and no gender predilection 1,2.

The diagnosis is based on the histological and immunohistochemical features 1.

Clinical signs and symptoms depend on the tumor location and might include dyspnea, cough, hemoptysis, palpitations, atrial fibrillation or peripheral edema, pleural effusion and ascites as well as non-specific symptoms like fatigue, malaise, fever or weight loss 1,2.

Cardiac leiomyosarcomas might cause the following 3,4:

Cardiac leiomyosarcomas are malignant mesenchymal tumors arising in the cardiac chambers that might be intracavitary or infiltrating. Rarely they might have a stalk 1,2.

Cardiac leiomyosarcomas most frequently arise from the left atrial free wall and less commonly from the right atrium or the ventricle and rarely from the interatrial septum 1,2.

Macroscopically, cardiac leiomyosarcomas have are multilobular nodular or polypoid, homogeneous sometimes whorled appearance with a white to tannish color and a firm consistency and variably areas of necrosis 1,2.

Microscopically, cardiac leiomyosarcomas are characterized by the following histological features 1,2:

  • intersecting fascicles of spindle-shaped or epithelioid cells
  • plump nuclei
  • moderate to abundant pale to bright eosinophilic cytoplasm
  • sometimes storiform or palisading patterns
  • mitosis readily seen
  • variably myxoid stroma
  • frequent necrosis in larger tumors

On immunohistochemistry cardiac leiomyosarcomas usually express smooth muscle actin and desmin 1.

Differentiation of cardiac leiomyosarcomas from other cardiac tumors is difficult. An associated pericardial effusion, a broad base and an immobile lesion point towards malignancy 3.

Echocardiography might show an echogenic mass of the cardiac chambers 3.

Cardiac leiomyosarcomas can be easily visualized with cardiac CT 2.

Cardiac MRI can detect tumors with high sensitivity and characterize the location and extent of the lesion 3-5.

  • T1: isointense
  • T2: hyperintense
  • T1C+ (Gd): heterogeneous early and late enhancement

The radiological report should include a description of the following:

  • type, location, extent and
  • lesion mobility
  • relation to other chambers and valves
  • extension to adjacent structures
  • pericardial effusion

Cardiac leiomyosarcomas are aggressive neoplasms. The mainstay in management consists of surgical excision with adjuvant chemotherapy or radiotherapy posing an uncertain asset. Local recurrences and distant metastasis are common with 5-year survival rates of approximately 25%. and a high mortality rate 1,2.

Condition or tumors that might mimic the imaging appearance of cardiac leiomyosarcomas include 1-3:

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