Carcinosarcoma
(Subset of sarcomatoid carcinoma)
Epidemiology and Etiology:
- Rare (4% of 0.1-0.4% sarcomatoid
carcinomas)
- Men > Women (7-8:1)
- Median 65 years
- Heavy smokers mostly
- Asbestos exposure (rarely)
Common sites:
Gross features:
- Grey-white, necrotic, hemorrhagic mass
Histologic features:
- Mixture of NSCLC (typically SqCC
or ADC) and sarcoma-containing heterologous elements:
- NSCLC component:
- SqCC is most common NSCLC component
- Most conventional NSCLC component
- High-grade fetal adenocarcinoma
- Clear cell adenocarcinoma
- Sarcomatous components in order of decreasing frequency:
- Rhabdomyosarcoma
- Chondrosarcoma
- Osteosarcoma
- Liposarcoma (rare)
- Angiosarcoma (rare)
- Diagnosis should list all histological types of
carcinoma and sarcoma present.
- Metastases may contain carcinoma, sarcoma, or
both
- Rare occurrence of neuroendocrine components is
better classified as combined small cell lung carcinoma or combined large
cell neuroendocrine carcinoma with associated sarcoma elements
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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S100
(chondrosarcoma
elements)
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Desmin
(rhabdomyosarcoma
elements)
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Myogenin
(rhabdomyosarcoma
elements)
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B-catenin
(strikingly restricted to the membrane of the epithelial component, unlike
classical pulmonary blastoma)
(high-grade
fetal adenocarcinoma component)
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Molecular features:
- TP53 mutations (frequent)
- KRAS mutation (less frequent)
- Not EGFR mutation (very uncommon)
Other features:
- Aggressive clinical behavior
- Poor prognosis (dependent on TNM factors)
- Distant metastases common
References:
- Travis et al.
WHO Classification of Tumours of the Lung,
Pleura, Thymus, and Heart, 4th ed. (2015)