Lung metastasis

Lung metastasis, also pulmonary metastasis and metastatic lung disease, is relatively common and generally carries a poor prognosis.

Lung metastasis
Diagnosis in short
Lung metastasis (Ewing sarcoma). H&E stain.
LM DDx	primary lung cancer
IHC	TTF-1 (-ve useful if non-squamous), CK20 (+ve suggestive colorectal carcinoma), CK7 (-ve useful if non-squamous), GATA3 (+ve suggestive UCC)
Site	lung
Clinical history	+/-hx of cancer
Prevalence	relatively common
Radiology	peripheral lung lesions, multiple
Prognosis	usually poor
Clin. DDx	lung primary, abscess

General

• Relatively common.

Microscopic

Features:

• Variable - dependent on site of origin.

Colorectal adenocarcinoma - usually distinctive morphologically:

• Typically gland forming.
  • Ellipsoid/elongated pseudostratified nuclei with moderate nuclear atypia.
  • +/-Dirty necrosis.

Others:

• Urothelial carcinoma - may mimic squamous cell carcinoma of the lung.
• Upper GI adenocarcinoma (e.g. gastric adenocarcinoma) - may mimic lung adenocarcinoma.
• Breast carcinoma - esp. ductal carcinoma of the breast - may mimic lung adenocarcinoma.

Images

• 

  Lung metastasis (ES) - intermed. mag.

• 

  Lung metastasis (ES) - high mag.

• 

  Lung metastasis (ES) - very high mag.

IHC

• TTF-1 -ve/+ve.
  • Negative suggestive of metastasis... unless it is squamous carcinoma.
• CK20 +ve/-ve.
  • Positive in colorectal carcinoma - very useful.
  • Negative in lung primaries.
• GATA3 +ve/-ve.
  • Usu. +ve in urothelial carcinoma.
  • Negative in lung primaries.
• CK7 -ve/+ve.
  • Positive in lung adenocarcinoma and small carcinoma of the lung.
  • Positive in a number of other tumours - breast, upper GI tract, thyroid, mesothelioma, salivary gland.
  • Negative in poorly differentiated carcinoma of the lung and squamous carcinoma of the lung.

See also

• Metastasis.