Gastric Adenocarcinoma with Enteroblastic Differentiation Presenting as Lung Nodules: A Diagnostic Dilemma

Lung malignancy, primary or metastatic, can present as chronic cough. It is imperative for patients to undergo a thorough workup for a timely diagnosis. IHC plays a vital role in delineating the origin of the malignant cells. GPC3 expression is the most sensitive marker for GAED. High serum AFP levels directly correlate with the strength of immunostaining and are associated with a poor prognosis. High HER2 expression and PDL-1 immunostaining is commonly seen in GAED cases with the most common mutation being p53. Currently, there are no set guidelines for management of GAED. Unresectable, metastatic HER2 positive conventional adenocarcinoma is being managed using platinum-fluoropyrimidine doublet therapy with anti-HER2 monoclonal antibody trastuzumab. This case report calls for aggressive IHC staining for prompt diagnosis where necessary as well as proper guidelines for management.