Melissa L. Rosado-de-Christenson, MD, FACR

Axial CECT shows multiple bilateral peripheral well-defined lung nodules from hematogenous metastases. Note the feeding vessel sign image.

Axial NECT shows lobular multifocal peripheral nodules and masses of various sizes from hematogenous metastases from adenoid cystic carcinoma.



  • Metastasis: Spread of disease from 1 organ to another nonadjacent organ or body part

    • Used to describe spread of malignant neoplasms and infections

  • Ability to metastasize is hallmark of malignancy

  • Metastatic pathways: Hematogenous, lymphatic, and endobronchial

  • Proposed mechanism of hematogenous metastases

    • Invasion of vascular structures by tumor cells

    • Transport of tumor cells in bloodstream

    • Arrest of tumor cells in filtering organ

    • Adherence to vessel walls and subsequent extravasation into tissues

    • Micrometastasis

  • Lung is most common site of metastases: Up to 50% at autopsy

    • Filtering organ; receives systemic venous drainage

    • “Seed and soil” hypothesis of chemokine-modulated “homing” of tumor cells to specific organs


General Features

  • Best diagnostic clue: Multifocal bilateral pulmonary nodules &/or masses

  • Patient position/location

    • Lung bases

    • Lung periphery; subpleural; outer 1/3 of lung

  • Size: Variable; 2-4 mm (miliary) to several centimeters

  • Morphology

    • Spherical with smooth margins

    • Also lobular and irregular-shaped

CT Findings

  • Multifocal bilateral pulmonary nodules and masses

  • More numerous in lung bases (dominant pulmonary arterial flow) and subpleural lung periphery (outer 1/3)

  • Variable size

    • Miliary nodules: Thyroid cancer, renal cell cancer, and melanoma

    • Large masses: Sarcomas, colon, and renal cancer

  • Morphology: Typically spherical

  • Margins: Well defined, smooth, lobular, irregular

  • Attenuation: Typically solid nodules

    • Ground-glass nodules: Hemorrhagic metastases, endobronchial dissemination, metastatic adenocarcinoma

    • Mixed attenuation nodules: Solid nodule surrounded by ground-glass; CT halo sign

  • Random or uniform distribution of nodules with respect to normal structures

  • Feeding vessel sign; association of nodule with pulmonary artery

  • Variable attenuation

    • Most are solid nodules

    • Ground-glass nodules: Metastatic adenocarcinoma

    • Nodules with surrounding ground-glass; hemorrhagic lesions

  • Lymphangitic carcinomatosis

    • Advanced adenocarcinoma

    • Hematogenous or lymphatic dissemination

    • Smooth &/or nodular thickening of interlobular septa

      • Peripheral reticular opacities

      • Central polygonal arcades

    • Thickening of peribronchovascular interstitium

      • Prominent central dot; thick centrilobular bronchovascular bundle

    • Asymmetric involvement (50%)

    • Normal pulmonary architecture

    • Lymphadenopathy (30-50%), pleural effusion (30%)

  • Unusual manifestations

    • Solitary nodule (2-10%)

      • Colon and kidney primaries, melanoma, sarcoma

      • New primary lung cancer must be excluded

    • Cavitation (4%): Typically from central necrosis

      • Cavity walls usually thick and nodular

      • Squamous cell carcinomas: Head & neck and cervical cancer

      • Adenocarcinomas and sarcomas

      • Treated metastases

      • Metastatic osteosarcoma may result in spontaneous pneumothorax

    • Calcification typically in bone-forming neoplasms

      • Osteosarcomas, chondrosarcomas; also mucinous adenocarcinomas

    • Endobronchial metastases (2%)

      • Typically renal cell carcinoma; also melanoma, breast cancer

      • May mimic central primary lung cancer

      • May produce mucus plugs, atelectasis, postobstructive pneumonia

    • Intravascular tumor emboli

      • 2.5% of autopsied malignancies

      • Occlusion and enlargement of pulmonary arteries by tumor

      • Branching nodular enlargement of small and medium-sized pulmonary arteries

  • Other thoracic metastases

    • Pleural metastases

      • Pleural effusion, exudate, may be large

      • Solid pleural nodules

      • Pleural effusion and solid pleural nodules

      • Circumferential nodular pleural thickening

    • Lymphadenopathy

      • Genitourinary, breast, head and neck primaries, melanoma

      • Typically right paratracheal; other lymph node groups affected

Radiographic Findings

  • Pulmonary nodules

    • Multifocal, bilateral, lower lobe predominant

    • Well-defined or ill-defined margins

    • Variable size

    • Rarely: Solitary nodule, calcification, cavitation, endobronchial metastasis

  • Lymphangitic carcinomatosis

    • Asymmetric reticular opacities

    • Thick interlobular septa; Kerley B lines

    • Pleural effusion; lymphadenopathy

  • Pleural metastases

    • Pleural effusion

    • Pleural masses

    • Circumferential nodular pleural thickening

  • Mediastinal lymphadenopathy

    • Genitourinary malignancies, breast cancer, head and neck cancer

    • Right paratracheal lymphadenopathy

Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Metastases

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