Hi Steve, Becky has the JAK2 mutation which, from my understanding, makes primary ET more likely, along with the elevated platelets. The mutation can be indicative of a myeloproliferative disorder, such as ET, PV, myelofibrosis. A bone marrow biopsy would be necessary to check for megakaryocytes.
Secondary or reactive thrombocythemia is generally caused by chronic inflammatory conditions such as rheumatoid arthritis, chronic inflammatory bowel disease, acute infections, etc. You mentioned Lyme disease which can cause inflammation but I did a little research and only found cases of thrombocytopenia (reduced platelets) associated with Lyme.
Asking questions of her oncologist certainly isn’t pushing buttons. You’re both concerned and want to make sure this is the right diagnosis. You could ask for a bone marrow biopsy. And of course, you can also ask for a second opinion!
Do you have other hematology/oncology options nearby?