Final answer:
The patient's symptoms suggest Hairy Cell Leukemia (HCL), typically associated with a BRAF V600E gene mutation which leads to the uncontrolled growth of B lymphocytes.
Step-by-step explanation:
Diagnosis and Mutation
The patient's symptoms of cytopenia, splenomegaly, and the presence of atypical "hairy" lymphocytes are suggestive of Hairy Cell Leukemia (HCL), a rare type of chronic lymphoid leukemia. This disease is characterized by the abnormal accumulation of B lymphocytes. The classic mutation associated with HCL is in the BRAF gene, specifically the V600E mutation. The BRAF gene mutation leads to a constitutive activation of the BRAF protein kinase, which in turn promotes cell growth in a manner that contributes to the development of leukemia.
Patients with HCL may present with symptoms such as fatigue, recurrent infections due to immune suppression, and could have physical findings that include an enlarged spleen (splenomegaly) and low blood counts (cytopenia) affecting various cell lines. Treatment generally involves targeted therapies that specifically inhibit the BRAF protein kinase pathway, among other options based on the patient’s specific characteristics and needs.