Signet ring cell adenocarcinoma of the lung with an EML4-ALK fusion gene mimicking mucinous (colloid) adenocarcinoma: A case report

We herein report a case of signet ring cell adenocarcinoma of the lung with an EML4-ALK fusion gene mimicking mucinous (colloid) adenocarcinoma. A 79-year-old female presented with a pulmonary tumor located in the right lower lobe measuring 21 mm in size. A right lower lobectomy was performed. The postoperative pathological examination revealed signet ring cell carcinoma with abundant mucin pools, and a multiplex RT-PCR analysis revealed the variant 2 inversion of the EML4-ALK gene.