Introduction: Histiocytic sarcomas are malignant proliferation of cell showing morphological and immunophenotypic characteristics of mature tissue histiocytes.
Objective : Is to report 3 years old girl presented with pyrexia of unknown origin and after echocardiography, MSCT on heart and MRI heart, the case was reported to have cardiac mass then after excisional biopsy of the mass and immunohistochemisrtry,histiocysticneoplasia was diagnosed.
Conclusion: Cardiac tumor should be excluded in the case of pyrexia of unknown origin.