A case report of histiocytic sarcoma mimicking acute pericarditis.

Background: Pericardial masses are rare disease requiring incremental diagnostic workout to differentiate benignant from malignant lesions. No solid evidence exists regarding their management, and their treatment requires a case-by-case evaluation. Case summary: A 54-year-old man was diagnosed with a pericardial mass. After performing cardiac magnetic resonance and computed tomography, a high suspicion of malignancy was raised. Positron emission tomography and pericardial biopsy confirmed the presence of a primary histiocytic sarcoma. After multidisciplinary evaluation, the mass was considered not suitable for surgical removal, and a neoadjuvant chemotherapy strategy was started. The first chemotherapy regimen-consisting of cyclophosphamide, doxorubicin, etoposide, vincristine, and methylprednisolone-was not effective. Therefore, a second, more aggressive, regimen consisting of cladribine, cytarabine, granulocyte-colony stimulating factor, and mitoxantrone was started. Following the first cycle, the patient developed bone marrow aplasia and septic shock leading to the exitus. Discussion: Histiocytic sarcomas primarily involving the heart are extremely rare. Surgical excision represents the first therapeutic choice when feasible. When not pursuable, a neoadjuvant therapy is preferred, although no consensus exists regarding the chemotherapy regimen.