Benign Tumors of Lungs

Question 1

Prevelence of benign lung tumors

Answer 1

• uncommon (<1% of all resected lung tumors)
• overall 2-5% of primary lung tumors

Question 2

General categorization of benign lung tumors

Answer 2

• Based upon location
  
  • Endobronchial
  • Parenchymal
• Histology (cell of origin)

Question 3

Definition of solitary pulmonary nodule (SPN)

Answer 3

Rounded lesion with well-demarcated margins ranging in size from mm-cm

Question 4

Important considerations during radiolgic evaluation of SPN

Answer 4

• Doubling time
  
  • < 10 days or >450 days most likely benign
• Calcification pattern (benign)
  
  • central
  • diffuse
  • speckled
  • laminar
  • popcorn appearance

Question 5

Calcification of malignant appearing SPN

Answer 5

Eccentric calcifications

Question 6

CT scanning sensitiviety in determining malignancy for SPN

Answer 6

CT scan (1 mm cuts):

91% sensitive

Question 7

CT characteristics of malignancy with SPN

Answer 7

• Ill-defined boarders
• Spiculation
• Involvment of bronchi

Question 8

Efficacy of CT guided core needle biopsy (CNB) of SPN

Answer 8

82% accuracy in providing definitive diagnosis

(FNA 17% accurate)

Question 9

Sensitivity of PET in distinguishing benign vs. malignant SPN

Answer 9

90% sensitivity when nodule >= 10 mm in size

Question 10

Glucose avid nodule with SUV >= 2.5 on PET scan has _% of chance of being malignant

Answer 10

>90% chance of malignancy

Question 11

2 primary indications for sugical excision of SPN

Answer 11

• Nodules > 10 mm with malignant characteristics
• Indeterminate SPN by other means

Question 12

Lung lesion:

Mixed lesion arising from epithelial and mesodermal cells

Answer 12

Hamartomas

Most common benign lesion of lung (75% of all bening lung tumors)

8% of radiologic “coin lesions”

Question 13

Characteristics of hamartoma

Answer 13

Slow growing (~3-5 mm/year)

More common men

Usually found in 6-7th decade of life

Peripheral location MC (may occur centrally or endobronchially)

Question 14

CT appearance of hamartoma

Answer 14

1 - 3 mm smooth, lobulated, well-circumscribed, smoothly marginated, peripheral lesion with mixed fat and smooth tissue attenuation

Question 15

ID the Lesion:

Answer 15

Lung Harartoma:

1 - 3 mm smooth, lobulated, well-circumscribed, smoothly marginated, peripheral lesion with mixed fat and smooth tissue attenuation

Question 16

Presence of fatty tissue within SPN lesion highly suggestive of

Answer 16

Lung harmartoma

Present ~ 50% of time

Question 17

On CXR, popcorn-like calcifications can occur with hemartomas in ~ _% of cases

Answer 17

10-30%

Question 18

Management of hamartoma

Answer 18

• If stable, observation
  
  • Regular followup and serial imaging essential if lesion not resected
    
    • Rate, but real rate of malignant transformation

Question 19

Benign tumors of epithelial origin

Answer 19

• Endobronchial
  
  • Papillomas
  • Mucus gland adenoma
• Parenchymal
  
  • Mucinous cystadenoma
  • Alveolar adenoma
  • Pleomorphic adenoma

Question 20

Characteristics of papillomas

Answer 20

• Relatively common
• Endobronchial location
• Adults
  
  • Solitary
  • Men, 50-60 years, smoker
• Children:
  
  • Multiple
  • Vocal cord or tracheal involvement

Question 21

Histologic characteristics of papillomas

Answer 21

Clara cells

Question 22

TOC for papillomas

Answer 22

Laser ablation or endoscopic removal

Risk of malignant degeneration

Question 23

Characteristics of Mucus Gland Adenomas

Answer 23

• Arise from submucosal mucus glands in lobar or segmental bronchi
• Coin like lesions on CT

Question 24

Tumors of mesodermal origin

Answer 24

• Endobronchial
  
  • Benign endobronchial histiocytoma
• Parenchymal
  
  • Intrapulmonary fibrous tumor
  • Hemangioma
    
    • Cavernous hemangioma
    • Sclerosing hemangioma
    • Pulmonary capillary hemangioma
  • Chondroma
  • Leiomyoma

Question 25

Benign tumor arising from visceral pleura, presenting as large, asymptomatic mass

Answer 25

Intrapulmonary fibrous tumor

(aka localized pleural mesothelioma, pleural fibroma, solitary fibrous tumor of pleura)

• Appear to make an obtuse angle with the chest wall, revealing they arise from pleura and not lung on imaging.
• Not associated with asbestos
• Associated with paraneoplastic syndrome: 3-4% of cases
  
  • hyperglycemia (insulin-like substance secreted from tumor)

Question 26

Benign lung tumor associated with paraneoplastic disorder (hyperglycemia) due to insulin-like hormone secretion

Answer 26

Intrapulmonary fibrous tumor

Question 27

Presence of _ should raise suspicious of Osler-Weber-Rendu syndrome (hereditary hemorrhagic telangiectasia)

Answer 27

Pulmonary cavernous hemangioma

Question 28

Presence of pulmonary chrondroma should raise suspicous of __

Answer 28

Carney’s Triad:

• Pulmonary chondroma
• GIST tumor
• Extra-adrenal paraganglioma

Question 29

Carney’s Triad

Answer 29

1. Pulmonary chondroma
2. GIST tumor
3. Extra-adrenal paraganglioma

• MC in females

Question 30

Characteristics of leiomyomas

Answer 30

• Can occur endobronchially or in lung parenchyma
• 2% of bening lung lesions
• MC in femals and young adults
• Considered metastasizing when occuring concurrently with uterine leiomyomas
  
  • Can be fatal

Question 31

TOC for lung leiomyoma

Answer 31

Surgical resection

Chemotherapy

Hormonal manipulation

Question 32

Benign lung lesion associated wtih multiple myeloma

Answer 32

Nodular amyloid

• 3 cm in size
• esosinophilic deposits with “apple-green birefrigence” on histology
• Long-term followup necessary d/t association with macroglobulinemia and lymphoma

Question 33

Benign lung lesion with prsence of thymic tissue in intrapulmonary locations

Answer 33

Primary pulmonary thymoma

• Very rare
• Likely d/t embrologic descent of thymic tissue to position more inferior than nl