Atypical pulmonary metastasis: imaging findings

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