TTF1 and cholangiocarcinoma: The positive expression of CK7 and CK19, commonly associated with CCA, coupled with the absence of TTF-1 and napsin, indicates a distinctive immunostaining pattern.[5] This intricate diagnostic process was further enriched by a tumor board discussion, in which multidisciplinary experts collectively reviewed the patient’s case, incorporating past medical records highlighting a history of CCA and subsequent brain metastasis.