Lung metastasis

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)
Gross	lung nodules - typically multiple and peripheral
Site	lung
Clinical history	+/-hx of cancer
Prevalence	relatively common
Radiology	peripheral lung lesions, typically multiple
Prognosis	usually poor
Clin. DDx	lung primary, abscess

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

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.