This particular variant of lung cancer is usually asymptomatic and is found after chest x-rays are taken for other reasons. Hemoptysis is seen occasionally and, in some cases, distal obstruction of bronchi by blood clots or mucus plugs produces cough and/or infection. Lesions often enlarge and progress slowly, over many years. The 1999 World Health Organization classification system defined MCACL as a cystic adenocarcinoma with copious mucin production that, histologically, resembles (the more common) mucus-producing<unk> s originating in the ovary, breast and pancreas. The 2004 revision of the WHO classification noted that the tumors tend to be well circumscribed by a partial fibrous tissue capsule with central cystic change and copious mucin pooling. The thin, fibrous wall circumscribing the tumor is highly characteristic of this lesion. It can sometimes occur within a pulmonary bronchocele, and this tumor entity should be kept in mind after identification of a bronchocele with suspicious or non-prototypical imaging characteristics. Microscopically, the neoplastic epithelial cells tend to grow along the alveolar walls, in a fashion similar to the<unk>  variant of bronchioloalveolar carcinoma, a more common form of adenocarcinoma. Hemoptysis is seen occasionally. Positron Emission Tomography (PET) scanning can be of assistance in diagnosing MCACL, as these lesions show intense uptake, typically in the wall of the tumor. CA 19-9 has been reported to be elevated in MCACL. Differential diagnosis of MCACL includes secondary metastatic<unk> tous lesions, particularly from the pancreas or ovary, mucoepidermoid carcinoma, and pulmonary<unk>  bronchioloalveolar carcinoma. The mouse monoclonal antibody 1D3, developed to detect a high molecular weight mucin found in a number of cystic malignancies of various organs, may be of use in differentiating primary<unk>  from metastatic lung tumors due to<unk>  cystic lesions of the uterus and pancreas, as well as those primary in the colon and stomach.
Mucinous cystadenocarcinoma of the lung
Epithelial-myoepithelial carcinoma of the lung
Atypical pulmonary carcinoid tumour
Salivary gland–like carcinoma of the lung
Large cell neuroendocrine carcinoma of the lung
Giant-cell carcinoma of the lung
Sarcomatoid carcinoma of the lung
Basaloid large cell carcinoma of the lung