36.A 60-year-old man presents with dyspnea and non-productive cough. Imaging reveals a peripheral lung
mass. Biopsy shows malignant glands producing mucin with irregular, infiltrative growth and desmoplastic stroma. Which additional finding would most strongly support a primary lung adenocarcinoma rather than a metastasis from the colon?
(A) Presence of signet-ring cells in the tumor
(B) Strong, diffuse cytoplasmic CDX2 positivity p
(C) Immunoreactivity for thyroid transcription factor-1 (TTF-1)
(D) Loss of expression of E-cadherin