Clinical History:

An 82-year-old woman was admitted to the hospital with a history of worsening, severe respiratory distress over the past two days. History revealed that she had undergone mastectomy seven months previously.

The chest radiograph shows multiple metastatic tumor nodules. Microscopically, many small vascular and lymphatic channels show masses of atypical epithelial cells with numerous mitotic figures. Some bronchi have also been infiltrated by tumor and this accounts for atypical epithelial cells in bronchi, which could have possibly been recognized in a sputum cytology specimen. Tumor cells show no distinct glandular or keratinizing features.

Questions:

1. What are typical routes for metastases? How do these routes differ in regard to the primary site and cell of origin?

Carcinomas often spread via lymphatics to regional lymph nodes. The primary site will determine which nodes are affected--thus enlarged hilar nodes suggest a lung primary, axillary nodes a breast primary, cervical nodes a head & neck primary, etc. Carcinomas may also spread locally by direct extension, to distant sites via the bloodstream, and by seeding through body cavities (such as over pleural or peritoneum. Sarcomas are less likely to use lymphatic spread and more likely to use hematogenous spread.

2. How did the metastases account for the clinical presentation?

The metastases occluded vascular channels in the lung (tumor emboli), leading to an appearance similar to pulmonary embolization. If larger metastatic lesions are present, they can compromise lung function by simply reducing lung capacity or obstructing bronchi.