A distinctive chronic lymphoproliferative disorder is hairy cell leukemia (HCL). It is linked with autoimmune disorders and can impersonate or coexist with clonal hematologic disorders. It ought to be engaged as a different diagnosis in patients with cytopenias being assigned the diagnosis of aplastic anemia, hypoplastic myelodysplastic syndrome, atypical chronic lymphocytic leukemia, B-prolymphocytic leukemia, or idiopathic myelofibrosis. Even though nonspecific chromosomal and molecular changes have been detailed, causative etiology or molecular defects stay vague. A middle-aged man with an incidental finding of pancytopenia, splenomegaly, and inaspirable bone marrow is a standard presentation. Incredibly high, durable, overall, and complete response rates are seen when purine analog, cladribine, or pentostatin are administered as part of the treatment. However, relapses and resistance to treatment were also noticed. A variant subtype is regularly linked with poor response. As initial therapy, cladribine is regularly utilized because of its simplified dosing scheme. The duration of the previous remission determines the treatment process of the relapsed hairy cell leukemia. The same original agent can be utilized to treat the relapsed disease successfully after a lengthy remission. The alternate purine analog is used to treat the resistance in regular hairy cell leukemia. The assessment of new agents, such as BL22 and rituximab, are continuing and they demonstrated promising outcomes in both hairy cell leukemia subtypes. The review utilizes two patients with aplastic anemia to deliberate the hairy cell leukemia’s biology, pathogenesis, clinical presentation, diagnostic evaluation, and treatment options.