The coexistence of non-small-cell lung cancer (NSCLC) with an EGFR mutation and adenocarcinoma of the ampulla of Vater represents a rare diagnostic and therapeutic challenge. A 66-year-old female patient with NSCLC harboring the p.(Leu858Arg) substitution in exon 21 underwent surgical treatment followed by osimertinib therapy due to recurrence. During treatment, imaging revealed ambiguous lesions in the liver and bile ducts, accompanied by cholestasis requiring repeated stenting. Histopathological examination of the ampulla of Vater demonstrated a moderately differentiated grade 2 (G2) adenocarcinoma with Ki-67 positivity and TTF-1 expression. The absence of EGFR mutation in the ampullary tumor supported the diagnosis of a second primary malignancy, leading to surgical qualification and discontinuation of osimertinib. This case highlights the importance of integrating clinical, imaging, pathological, and molecular data in distinguishing between metastatic disease and synchronous primary tumors.
Litkowska et al. (Wed,) studied this question.