IMTs occur mainly in the soft tissues and are composed with predominantly of inflammatory and myofibroblastic cells. It is Brunn who described the first case of IMT in the lungs in 1939 . Although it has been described in various lesions, cardiac lesions are much more uncommon. With our best knowledge, less than 50 cases of cardiac IMTs have been published in English since the initial description made by Gonzalez-Crussi in 1975 . Owing to its extremely rarity, the etiology of IMT still remains unresolved and the immunologic and infectious postulates are still to be validated.
According to our literature review, it may seem premature to establish an epidemiologic profile of cardiac IMT owing to its rarity, but several features are concluded: no gender predominance, predilection for children and young adult. More than two thirds of the cardiac IMT cases have been reported in children and adolescents. To our best knowledge, less than 10 cases of cardiac IMT involving older adult patients have been published before, which makes our case much rarer.
Histologically, IMT consists of a proliferation of spindle-shaped cells associated with no remarkable atypia or mitotic activity, corresponding to fibroblasts and myofibroblasts arranged in a myxoid stroma made of a diffuse inflammatory infiltration with a heterogeneous cell admixture, dominated by histiocytes and plasmocytes. Immunohistochemical analysis is highly contributive to the differential diagnosis, objectifying universally positive for vimentin, universally negative for CD34 and generally positive for CD68 and smooth muscle actin antibodies .
The clinical presentation of IMT depends on multiple factors including patient age, tumor size, location, rate of growth and individual tolerance. Patients with cardiac IMT are usually asymptomatic until hemodynamic changes and local invasion leading to cardiac insufficiency. Decreased exercise tolerance may be the most common symptom in the patients with cardiac IMT. Arrhythmia may emerge when the conduction system is involved or ectopic excitation foci occurs. Once the valves are involved, symptoms related to valvular stenosis or regurgitation like lower extremity edema, dyspnea, syncope, chest pain may manifest. Moreover, fever of unknown origin is another possible symptom of IMT which suggested the nature of immunological-related.
The natural history of IMT is unpredictable. Patients undergoing surgical resection of the tumor usually have a favorable prognosis, while patients with an unresectable tumor may have a poor one because of the unpredictable progression of the tumor, like sudden death or embolism. Spontaneous or steroid –induced regression have also been reported in cardiac IMT [4, 5].
There is consensus about surgical treatment in symptomatic patients with cardiac IMT , but it is still controversial whether performing surgery in asymptomatic patients. Recurrence of IMT is more likely to occur in patients with incomplete tumor resection. No distant metastasis has been documented.