Pulmonary metastasis is common, with the lungs acting as a filter for cancer cells from the lymphatic system. While multiple, round nodules in random distribution are typical, atypical presentations can include poorly-defined lesions, cavitation, calcification, hemorrhage, pneumothorax, airspace opacities, tumor emboli, endobronchial growths, solitary masses, or vessels within tumors. Certain primary cancers like sarcomas are also linked to specific radiologic appearances of pulmonary metastases. Awareness of atypical presentations helps avoid misdiagnosis versus primary lung disease.

1. Atypical pulmonary metastasis
Chest Conference
THORSANG CHAYOVAN
26.08.2014

4. Principle of pulmonary metastasis
• Lung is a filter-like organ
– The venous return contains lymphatic fluid from the
body tissues flows into the lung
• Pulmonary metastasis is extremely common
• Incidence of metastases to lung parenchyma
– 20% to 54% of patients who died of malignancy
• The common primary organs are:
– Breast, colon, kidney, uterus, H&N
– Choriocarcinoma, osteosarcoma, testis, melanoma,
Ewing’s sarcoma, thyroid carcinoma

5. Pathogenesis of pulmonary metastasis
• 5 mechanisms
1. Pulmonary or bronchial artery
2. Lymphatics
3. pleural space
4. Airway
5. Direct neoplastic invasion
• Hematogenous spread--most common
– Most reach the arterioles and capillary beds
– Some survive and grow into the interstitium

6. Typical pulmonary metastasis
• Hematogenous
-> Random distribution
-> Multiple
-> Round-shaped
-> Variable-sized
• Diffuse thickening of the interstitium
(lymphangitic carcinomatosis)

7. Atypical pulmonary metastasis
• Unusual radiologic features of metastases
– Poorly-defined/irregulary-marginate nodules
– Cavitation
– Calcification
– Hemorrhage around the metastatic nodules
– Pneumothorax
– Air-space pattern
– Tumor embolism
– Endobronchial metastasis
– Solitary mass
– Dilated vessels within a mass
– Sterilized metastasis

8. Nodule
• The most common presentation of metastasis
• Spherical nodules of varying size
• Random or peripheral
• Basal portion of the lung

9. • Tumor cells hematogenously transferred to
the lung proliferate into the perivascular
interstitium
– > interstitial lesions: clear, smooth margins
• Tumors grow out of vessels into the
interstitium and alveolar air space
– > lung parenchymal lesions
Nodule

10. • At autopsy,
– 38% well-defined, smooth margins
– 16% well-defined, irregular margins
– 16% poorly-defined, smooth margins
– 30% poorly defined, irregular margins

11. Comparison of HRCT to
histopathological characteristics
• Well-defined, smooth margins
– Expanding type
– Alveolar space-filling type
• Poorly-defined margins
– Alveolar cell type
• Irregular margins
– Interstitial proliferating type

12. Correlation between the histological
type of the primary tumor and the CT
appearance
• Well-defined smooth margin
– Expanding type
– Observed in most metastatic HCC
• Metastatic adenocarcinomas
– Poorly defined, either irregular or smooth margins
– alveolar cell type and interstitial proliferation type
• Irregular margins
– Metastatic squamous cell carcinomas
• Irregular margins
– Metastases after chemotherapy

13. Well-defined, smooth margin
HCC
Expanding type

14. Adenocarcinoma
Poorly-defined,
irregular margin
Alveolar cell type

15. Cavitation
• Incidence
– 4% in metastases
– 9% in primary lung cancer
• 70% are metastatic squamous cell carcinomas
• The most common primary organ
– Head and neck in males
– Genitalia in females
• Metastatic adenocarcinoma
– no statistically significant difference in the frequency of
cavitation between the two histologic types.
• Metastatic sarcoma
– Pneumothorax is a frequent complication
• Chemotherapy is known to induce cavitation
• Indeterminate mechanism

16. Aquamous cell CA

17. Adenocarcinoma of rectum

18. Angiosarcoma of scalp with
pneumothorax and hemorrhage

19. Squamous cell CA S/P chemotherapy

20. Calcification
• Benign nodules
– Granuloma
– Hamartoma: less common
• Calcification in metastasis

21. Calcification in metastasis
• Morphology-specific
1. Dense eccentric—osteosarcoma
2. Multifocal—osteosarcoma, chondrosarcoma
3. Dystrophic—after treatment
• Morphology-nonspecific
– Synovial sarcoma, giant cell tumor, colon, ovary,
breast, thyroid, choriocarcinoma

22. Osteosarcoma

23. Hemorrhage around metastatic
nodules
• CT halo sign
– nodular attenuation surrounded by a halo of ground-
glass opacity
• Ill-defined fuzzy margins NON-SPECIFIC!!
• Invasive aspergillosis
• Candidiasis
• Wegener granulomatosis
• Tuberculoma
• Bronchioloalveolar carcinoma
• Lymphoma

24. Hemorrhagic metastatic nodules
• Examples
– Angiosarcoma
– Choriocarcinoma

25. Choriocarcinoma with hemorrhagic metastasis
Multiple nodular attenuation with surrounding GGO

26. Pneumothorax
• A result of tumor necrosis
• In aggressive and necrotic tumors
– Osteosarcoma: most frequent—5-7% of cases
– Other sarcomas
• Necrosis of subpleural metastases produces a
bronchopleural fistula -> Pneumothorax
• 10 of 1,143 cases with a spontaneous
pneumothorax have been attributed
to a malignancy
• A spontaneous pneumothorax in a
patient with a sarcoma should raise
the possibility of occult pulmonary

27. Osteosarcoma with pneumothorax

28. Air-space pattern
• Metastases from an adenocarcinoma, breast and
ovary origin
– May spread into the lung along the intact alveolar
walls (lepidic growth)
– Also in BAC
• The radiologic features mimic pneumonia
– Air-space nodules
– Consolidation containing an air bronchogram
– Focal or extensive ground-glass opacities
– CT halo signs

29. Adenocarcinoma
of stomach

30. Tumor embolism
• In small or medium arteries
• Diagnosis is difficult radiologically
– Multifocal dilatation and beading of the peripheral
subsegmental arteries
– Infarction: peripheral wedge-shaped areas of attenuation
– Large tumor emboli in the main, lobar, or segmental
pulmonary arteries
• Tumors frequently associated with pulmonary tumor
emboli
– Hepatomas, breast and renal cell carcinomas, gastric and
prostatic cancers, and choriocarcinomas

31. HCC
with massive
tumor emboli

32. Endobronchial metastasis
• Rare
• Major airway in only 2% of cases
• Two possible routes
1. Directly on the bronchial wall
– Aspiration of tumor cells
– Lymphatic spread
– Hematogenous metastasis to the bronchial wall
-> polypoid lesion inside the bronchial lumen
2. Tumor cells in the lymph nodes or lung parenchyma that
surround the bronchus grow along the bronchial tree
-> intraluminal lesion

33. • Kidney, breast, and colorectal cancers
• The most common radiologic appearance
– Lobar atelectasis
RCC
Endobronchial metastasis

34. RCC with
endobronchial
metastasis

35. • Solitary metastasis without a history of
malignancy
– CT: 0.4%–9.0%
– Chest radiograph: 25%
• Solitary pulmonary nodules detected in
patients with extrapulmonary malignancies
– 46% proved to be a metastasis
Solitary metastasis

36. • The likelihood that a solitary nodule
represents a pulmonary metastasis
– varies according to the histologic type of the
primary tumor and the patient’s age
• The most frequent malignancies
– melanoma; sarcoma; and cancer of the colon,
breast, kidney, bladder, and testis
Solitary metastasis

37. Dilated vessels within mass
• Engorged tumor vessels
– Suggest hypervascularity
– Sarcoma
• Alveolar soft-part sarcoma
• Leiomyosarcoma

38. Dilated vessels in alveolar soft-part
sarcoma metastasis

39. Sterilized metastasis
• After adequate chemotherapy
• Necrotic nodules with or without fibrosis and
without viable tumor cells
• Histologic confirmation is necessary
• Common: choriocarcinoma and testis
• Germ cell tumors can convert to a benign
mature teratoma after chemotherapy and
result in persistence of the masses

40. Benign Metastasizing Tumor
• Rare
• Generally originate from
– Leiomyoma of the uterus
– Hydatidiform mole of the uterus
– Giant cell tumor
– Chondroblastoma
– Pleomorphic adenoma of the salivary gland
– Meningioma
• Despite their metastatic spread, these tumors are
histologically benign.
• Indistinguishable from malignant tumors, however,
benign ones show very slow growth

41. Benign metastasis
from a uterine leiomyoma

42. Conslusion
• Radiological diagnoses--based on typical
findings
• Awareness of the spectrum of radiologic
manifestations in atypical pulmonary
metastases
• Presence of atypical radiologic features and
metastasis is suspected
– > tissue diagnosis is recommended

43. Typical pulmonary metastasis
• Random distribution
• Lower distribution
• Multiple
• Round shape
• Variable size

44. Atypical pulmonary metastasis
• Poorly-defined/irregulary-marginate nodules
• Cavitation
• Calcification
• Hemorrhage

45. Atypical pulmonary metastasis
• Pneumothorax
• Air-space pattern
• Tumor embolism
• Endobronchial metastasis
• Solitary mass
• Dilated vessels within a mass
• Sterilized metastasis

46. THANK YOU
• "Atypical Pulmonary Metastases: Spectrum of
Radiologic Findings."RadioGraphics:. N.p., n.d. Web.
24 Aug. 2014.
• "Atypical Pulmonary Metastases: Spectrum of
Radiologic Findings."RadioGraphics:. N.p., n.d. Web.
24 Aug. 2014
References