Lung Neoplasms-General

Question 1

What are the general IHC findings in lung adenocarcinomas?

Answer 1

• Positive for:
  
  • TTF-1
  • Napsin-A
  • CK7
  • CEA
  • MOC-31

Question 2

What are the IHC markers associated with squamous cell carcinoma?

Answer 2

• Positive for:
  
  • CK7
  • CK5/6
  • MOC-31
  • p63
  • p40

Question 3

What are the markers associated with neuroendocrine carcinomas?

Answer 3

• Positive for:
  
  • CK7
  • CD56
  • CD57
  • Chromogranin
  • Synaptophysin

Question 4

What types of lung cancers are KRAS and BRAF mutations found preferentially in?

Answer 4

• Associated with smoking history
• 25% of cases harbor KRAS mutations
• 3% harbor BRAF
  
  • Note: BRAF is often seen in micropapillary subtype of lung carcinoma

Question 5

What clinical history are EGFR and ALK mutations associated with?

Answer 5

• ALK and EGFR are associated with no smoking history
• 20% of tumors have EGFR mutations
• 5 % have ALK mutations
• NOTE: ALK and EGFR mutations are usually mutually exclusive

Question 6

What is the pattern of involvement of lymphom in the lung?

Answer 6

• Lymphoma involves the lung in a nodular growth pattern that follows the lymphatic routes (follows bronchovascular bundles within interlobular septa)

Question 7

What is the differential diagnosis of a lung lymphatic pattern?

Answer 7

• macrophage disorders
• lymphoma (BALT/Marginal zone lymphoma)
• lymphangitic carcinoma
• sarcoid
• kaposi sarcoma
• lymphangiectasia (pediatric condition)
• lymphangiomatosis (pediatric condition- not LAM)

Question 8

What is one feature that can help differentiate the small cell variant of squamous cell carcinoma from small cell carcinoma?

Answer 8

Presence of nucleoli favors squamous cell, small cell variant

Question 9

What does TTF-1 stain positive for primary lung carcinomas?

Answer 9

• Positive in:
  
  • Small cell lung carcinoma
  • Majority of adenocarcinomas
  • Rarely positive in squamous cell

Note: most lung carcinomas are CDX2 negative, except for mucinous pulmonary adenocarcinomas.

Question 10

Mutations in Beta-catenin are seen in which pulmonary carcinoma?

Answer 10

• mutations in Beta-catenin are rare in pulmonary carcinomas
• associated with well differentiated fetal type adenocarcinoma

Question 11

What is a common mutation seen in squamous cell carcinomas?

Answer 11

• amplifications of chromosome 3q (involves the SOX2 gene)
• some cases p63

Question 12

When something is described radiologically as “popcorn calcifications” within the lung, what entity is this most referring to?

Answer 12

• Pulmonary Hamartoma
  
  • often carry cytogenetic abnormalities in chromosome 6 and 12
  • defined by 2 mesenchymal elements: often cartilage, bland mesenchymal cells or adipose tissue
  • often peripherally located

Note: some cases can have chondrosarcomas arise from them

Question 13

What are the 3 features of pulmonary hamartoma?

Answer 13

• areas of well-formed cartilage
• adipose tissue
• invaginated respiratory epithelium

Question 14

What is the differential diagnosis of pulmonary hamartomas?

Answer 14

• Bronchial chondroma
  
  • does not have invaginations of the epithelium
  • may be associated with gastric smooth muscle tumors
• Pleomorphic adenoma
• Chondrosarcoma (primary or metastatic)
• Bronchial lipomas
• Bronchial teratoma
  
  • will see 3 germinal layers (tissues arising from them)

Question 15

What is the definition of lymphomatoid granulomatosis of the lung?

Answer 15

• angiocentric lymphoproliferative disorder (key is the location) composed of EBV infected B cells admixed with reactive T cells
  
  • Transmural infiltration of small and medium sized vessels by atypical lymphocytes.
    
    • generally arises in a setting of immunodeficiency
      
      • AIDS, transplants, Wiskott-Aldrich syndrome
    • also affects skin and CNS
    • can transform to to DLBCL
    • decreased total T cells, CD4 and CD8

Question 16

What are the features of the fetal-type adenocarcinoma of the lung?

Answer 16

• composed of glandular elements of columnar cells with prominent subnuclear and supranuclear glycogen vacuoles
• squamoid morules are also a distinctive feature of this tumor
• no blastema component is seen
  
  • This is a feature often seen in blastematous elements
• tumor will be TTF-1 positive and PAX-8 negative

Question 17

What are features of pulmonary blastoma?

Answer 17

• this is considered a subset of sarcomatoid carcinomas
• biphasic tumor with a primitive epithelial component that ofte resembles a fetal adenocarcinoma
  
  • Also, there is a primitive spindled component which can have a blastemal component
  • Note: spindled component can have components including: rhabdomyosarcoma, chondrosarcoma, or osteosarcoma