[A case of amylase-producing lung cancer]

A 72-year-old man was admitted to our hospital because of progressive dyspnea due to pulmonary emphysema. Chest CT revealed a nodular lesion in the right S6 and swollen right hilar lymph nodes. The diagnosis was not confirmed bronchoscopically. A subsequent biopsy of a subcutaneous mass in the left lateral pectoral region demonstrated metastatic cancer. Laboratory data on admission showed marked elevation of amylase activity in both serum and urine. Amylase isozyme patterns identified the salivary types. The pancreas and salivary glands were unlikely to have any clinical involvement in the hyperamylasemia, but lung cancer with subcutaneous metastasis was strongly suspected clinically as the source. Chemotherapy failed to prevent tumor progression and the patient eventually died of respiratory failure. Immunohistological examination of the subcutaneous lesion showed positive staining for salivary-type amylase, whereas that of the lung primary lesion disclosed small cell carcinoma and negative staining for amylase. In most cases, amylase-producing lung cancers have been diagnosed as adenocarcinoma. Amylase-producing small cell carcinoma is very rare.