Background. Based on the information obtained so far, COVID- 19 is relatively mild in children. We will present a 6-month-old male patient infected with COVID -19 in April 2020, while receiving HLH 2004 chemotherapy protocol with the diagnosis of familial (Genetic / Primary) Hemophagocytic Lymphohistiocytosis (HLH).

Case. Herein we present a case accompanied by a defective perforin gene defect in the primary HLH pathogenesis, Covid-19 infection with the presence of fever and hyperferritinemia, which was evaluated in favor of reactivation and the patient was given both the HLH-2004 chemotherapy protocol treatment and COVID -19 therapy as recommended by the guidelines. Our patient improved clinically and in terms of laboratory test results at the end of the 15 < sup > th < /sup > day of hospitalization and was discharged.

Conclusions. It should be remembered that COVID-19 can be seen with different clinical manifestations in the pediatric age group, and COVID-19 tests should be recommended, especially in children with immunosuppression and fever.

Keywords: COVID-19, hemophagocytic lymphohistiocytosis, perforin