Abstract Hairy cell leukemia (HCL) is a distinct subset of chronic lymphoid leukemia, presents with unique features, including the characteristic "hairy" projections seen in neoplastic B cells. We reported a case on hairy cell leukemia (HCL), emphasizing the challenges posed by this rare hematological malignancy, especially in the context of concurrent health crises such as the COVID-19 pandemic. This malignancy, though uncommon, necessitates comprehensive diagnostic methodologies, such as peripheral blood studies, flow cytometry, and bone marrow biopsy. Treatment strategies for HCL involve tailored approaches based on symptomatic presentations. Purine analogs, cladribine and pentostatin, stand as first-line interventions, showcasing efficacy in inducing and sustaining remission. However, the prolonged immunosuppression resulting from these treatments warrants vigilant monitoring for potential infectious complications. Emerging therapies, such as the BRAF inhibitor vemurafenib, provide additional options for refractory or progressive cases. The post-treatment phase demands meticulous follow-up, with an emphasis on regular blood work assessments by an oncology nurse and primary care physician. Our case further highlights the need for heightened awareness among healthcare professionals, particularly in the post-COVID-19 phase, where persistent symptoms led to the discovery of an underlying hematological disorder. Keywords: Hairy cell leukemia, Evan syndrome, Covid-19.