Atypical pulmonary metastasis

Chest Conference

THORSANG CHAYOVAN

26.08.2014

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

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

Typical pulmonary metastasis

• Hematogenous

-> Random distribution

-> Multiple

-> Round-shaped

-> Variable-sized

• Diffuse thickening of the interstitium (lymphangitic carcinomatosis)

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

Nodule

• The most common presentation of metastasis

• Spherical nodules of varying size

• Random or peripheral

• Basal portion of the lung

• 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

• At autopsy,

– 38% well-defined, smooth margins

– 16% well-defined, irregular margins

– 16% poorly-defined, smooth margins

– 30% poorly defined, irregular margins

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

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

Well-defined, smooth margin

HCC

Expanding type

Adenocarcinoma Poorly-defined, irregular margin

Alveolar cell type

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

Aquamous cell CA

Adenocarcinoma of rectum

Angiosarcoma of scalp with pneumothorax and hemorrhage

Squamous cell CA S/P chemotherapy

Calcification

• Benign nodules

– Granuloma

– Hamartoma: less common

• Calcification in metastasis

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

Osteosarcoma

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

Hemorrhagic metastatic nodules

• Examples

– Angiosarcoma

– Choriocarcinoma

Choriocarcinoma with hemorrhagic metastasis Multiple nodular attenuation with surrounding GGO

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

Osteosarcoma with pneumothorax

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

Adenocarcinoma of stomach

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

HCC with massive tumor emboli

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

• Kidney, breast, and colorectal cancers

• The most common radiologic appearance

– Lobar atelectasis

RCC

Endobronchial metastasis

RCC with endobronchial

metastasis

• 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

• 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

Dilated vessels within mass

• Engorged tumor vessels

– Suggest hypervascularity

– Sarcoma

• Alveolar soft-part sarcoma

• Leiomyosarcoma

Dilated vessels in alveolar soft-part sarcoma metastasis

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

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

Benign metastasis from a uterine leiomyoma

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

Typical pulmonary metastasis

• Random distribution

• Lower distribution

• Multiple

• Round shape

• Variable size

Atypical pulmonary metastasis

• Poorly-defined/irregulary-marginate nodules

• Cavitation

• Calcification

• Hemorrhage

Atypical pulmonary metastasis

• Pneumothorax

• Air-space pattern

• Tumor embolism

• Endobronchial metastasis

• Solitary mass

• Dilated vessels within a mass

• Sterilized metastasis

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