BTK and B-cell chronic lymphocytic leukemia: Here, we describe a case of a 76-year-old Caucasian male patient who moved from California to Wisconsin with a history of coccidioidomycosis infection of the left knee that reactivated decades later in his prosthetic knee shortly after being initiated on ibrutinib (Imbruvica), a Bruton tyrosine kinase (BTK) inhibitor, for chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL).