Definition/General
Introduction:
Pulmonary sarcomatoid carcinoma is a rare, aggressive subtype of NSCLC
Represents 0.1-0.4% of all lung cancers
Contains carcinomatous and sarcomatous components
Shows poor prognosis
Highly aggressive behavior.
Origin:
Arises from epithelial cells with sarcomatoid transformation
Shows epithelial-mesenchymal transition
Biphasic or monophasic patterns
Associated with smoking.
Classification:
WHO 2021: Pleomorphic carcinoma
Spindle cell carcinoma
Giant cell carcinoma
Carcinosarcoma
Pulmonary blastoma
Part of sarcomatoid carcinoma group.
Epidemiology:
Peak incidence 6th-7th decades
Male predominance (4:1)
Strong smoking association
Peripheral location
Large size at presentation.
Clinical Features
Presentation:
Cough
Dyspnea
Chest pain
Hemoptysis
Weight loss
Large peripheral mass
Advanced stage common.
Symptoms:
Persistent cough
Shortness of breath
Chest discomfort
Constitutional symptoms
Fatigue
Bone pain (metastases).
Risk Factors:
Heavy smoking
Male gender
Older age
Occupational exposures
Environmental carcinogens
Genetic predisposition.
Screening:
Chest CT
Large peripheral mass
Heterogeneous enhancement
Necrosis common
Staging workup
Tissue diagnosis essential.
Master Pulmonary Sarcomatoid Carcinoma Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Large, bulky mass
Gray-white, firm
Heterogeneous cut surface
Necrosis and hemorrhage
Peripheral location
Infiltrative margins.
Characteristics:
Fleshy consistency
Variegated appearance
Soft and firm areas
Extensive necrosis
Hemorrhage
Cystic change.
Size Location:
Peripheral/subpleural
Large size (>5 cm typical)
Upper lobe common
Pleural invasion
Chest wall extension.
Multifocality:
Usually solitary
Intrapulmonary metastases
Pleural implants
Distant metastases
Lymph node involvement.
Microscopic Description
Histological Features:
Biphasic pattern: carcinomatous and sarcomatous
Monophasic sarcomatoid
Spindle cell morphology
Giant cells
High-grade features
Extensive necrosis.
Cellular Characteristics:
Pleomorphic cells
Spindle cells
Giant cells
High nuclear grade
Abundant mitoses
Atypical mitoses.
Architectural Patterns:
Fascicular arrangement
Storiform pattern
Solid sheets
Carcinomatous areas (adenocarcinoma, squamous)
Heterologous elements (carcinosarcoma).
Grading Criteria:
High-grade by definition
Marked pleomorphism
High mitotic rate (>10/10 HPF)
Extensive necrosis.
Immunohistochemistry
Positive Markers:
Pan-cytokeratin - positive (focal)
CK7 - variable
EMA - positive
p53 - often positive
Vimentin - positive (sarcomatoid areas).
Negative Markers:
TTF1 - usually negative
Napsin A - negative
p40 - negative (unless squamous differentiation)
Desmin - negative
MyoD1 - negative.
Diagnostic Utility:
Cytokeratin positivity confirms epithelial origin
Vimentin highlights sarcomatoid areas
Organ-specific markers rule out metastases
Myogenic markers negative.
Molecular Subtypes:
Pleomorphic carcinoma: Mixed markers
Spindle cell carcinoma: Focal CK+
Giant cell carcinoma: Variable CK
Carcinosarcoma: Specific lineage markers.
Molecular/Genetic
Genetic Mutations:
TP53 mutations (90%)
KRAS mutations
STK11 mutations
KEAP1 mutations
PIK3CA mutations
Complex karyotype.
Molecular Markers:
p53 pathway disruption
PI3K/AKT activation
EMT pathway activation
DNA repair defects
Chromosomal instability.
Prognostic Significance:
Very poor prognosis
Median survival <12 months
High metastatic rate
Resistance to conventional therapy
Stage critical.
Therapeutic Targets:
Platinum-based chemotherapy
Immunotherapy (anti-PD-1/PD-L1)
Sarcoma regimens
Clinical trials
Aggressive multimodal treatment.
Differential Diagnosis
Similar Entities:
Primary pulmonary sarcoma
Metastatic sarcoma
Inflammatory myofibroblastic tumor
Solitary fibrous tumor
Mesothelioma (sarcomatoid).
Distinguishing Features:
Sarcomatoid carcinoma: Focal cytokeratin+
Primary sarcoma: CK negative
Metastatic: Clinical history
IMT: ALK+, younger age
SFT: STAT6+
Mesothelioma: Calretinin+.
Diagnostic Challenges:
Extensive sampling needed
Focal cytokeratin staining
Metastatic vs primary
Crush artifact
Heterologous elements.
Rare Variants:
Carcinosarcoma (heterologous elements)
Pulmonary blastoma
Giant cell carcinoma
Spindle cell carcinoma.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[Lobectomy/pneumonectomy] with large peripheral mass
Tumor Description
Large sarcomatoid carcinoma measuring [X] cm with heterogeneous appearance
Microscopic Features
High-grade malignant neoplasm with sarcomatoid morphology and pleomorphic cells
Component Assessment
[Biphasic: [%] carcinomatous, [%] sarcomatoid / Monophasic sarcomatoid]
Immunohistochemistry
Pan-cytokeratin: [Positive (focal)/Positive], Vimentin: Positive, TTF1: [Negative/Positive]
pT Stage
pT[stage] - [staging details]
Margins
Surgical margins: [status]
Lymph Nodes
[X] of [Y] lymph nodes positive
Final Diagnosis
Sarcomatoid carcinoma ([pleomorphic/spindle cell/giant cell] type), pT[stage]N[stage]
Prognosis
High-grade malignancy with poor prognosis. Aggressive multimodal treatment recommended.