A unique case of an alpha-fetoprotein-producing lung cancer with testicular metastasis.

Alpha-fetoprotein (AFP)-producing primary lung tumours are rare; we present the first case of an AFP-producing lung tumour with metastasis to testes. The patient, a 72-year-old man, presented with a history of flu-like symptoms and abdominal pain. On examination he had a hard, tender left scrotal mass. Imaging showed a 4.4-cm right lower lobe lung mass and the serum-AFP was raised (1189 ng/mL). Left orchidectomy excised a necrotic tumour. Microscopy showed complete hemorrhagic infarction and immunohistochemistry showed a lack of staining for AFP. Serum-AFP rose 3 days post-orchidectomy to 1466 ng/mL. The patient subsequently developed melaena and died. Autopsy revealed a 9 × 5-cm necrotic right lower lobe lung tumour. Immunohistochemistry showed the tumour cells reacted with a pan-cytokeratin antibody and less than 5% expressed AFP. Bilateral adrenal tumour deposits were also identified in addition to those in the bowel and spleen. The expression of AFP solely in the lung lesion and lack of expression in both testes, together with a rise in serum-AFP post-orchidectomy and the bilateral adrenal metastases, is overwhelming evidence for the reversal of the usual situation: a poorly differentiated AFP-secreting metastatic lung adenocarcinoma.