Sarcomatoid carcinoma of the lung pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Trusha Tank, M.D.[2]

Overview

The exact pathogenesis of [disease name] is not fully understood.

OR

It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].

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[Pathogen name] is usually transmitted via the [transmission route] route to the human host.

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Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.

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[Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].

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The progression to [disease name] usually involves the [molecular pathway].

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The pathophysiology of [disease/malignancy] depends on the histological subtype.

Pathophysiology

Physiology

The normal physiology of [name of process] can be understood as follows:

Pathogenesis

• The pathogenesis of sarcomatoid carcinoma of the lung is characterized by a rare epithelial origin and morphologic features suggestive of a malignant mesenchymal tumor.
• Four major hypotheses may explain sarcomatoid neoplasms:
  • The embryonic rest hypothesis: This theory suggests that sarcomatoid tumors are the result of misplaced “mini-organs” that has epithelial and stromal component.
  • The collision hypothesis: This theory implies separate but concomitant malignant proliferation of epithelium and mesenchyme.
  • The stromal induction/metaplasia hypothesis: This theory suggests that sarcomatous elements are an atypical response to the growth of a carcinoma.
  • Totipotential hypothesis: This hypothesis proposes an origin from a single totipotential stem cell that differentiates into epithelial and mesenchymal components.

Genetics

• The development of sarcomatoid carcinoma is the result of multiple genetic mutations such as:
• EGFR
• K-ras

Associated Conditions

Conditions associated with [disease name] include:

• [Condition 1]
• [Condition 2]
• [Condition 3]

Gross Pathology

• Sarcomatoid carcinomas can arise centrally or peripherally.
• Most commonly present as poorly circumscribed solitary peripheral masses.
• Sarcomatoid carcinoma is commonly found in upper lobe of lungs.
• Tumors are large, ranging from 1 to 13 cm, with a median of 4.9 cm, and often invade the chest wall.
• Tumor consistency is described as soft and fleshy or firm, hard, or rubbery.
• Cut surfaces vary from white-grey to yellow, frequently show hemorrhagic and necrotic foci, and occasionally demonstrate cavitation.

Microscopic Pathology

• On microscopic histopathologically sarcomatoid carcinoma is classified into 5 subtypes:
  • Pleomorphic carcinoma
    • Poorly differentiated, sarcomatoid carcinoma composed of malignant, spindle and giant cells.
    • Spindle cell may vary from epithelioid to strikingly spindled and are arranged in haphazard fascicles or storiform pattern.
    • Giant cells are discohesive, uni/multinucleated, have moderate to abundant, dense, eosinophilic cytoplasm which may show emperipolesis by polymorphonuclear leukocytes or lymphocytes.
    • Giant cells are anaplastic, with many bizarre forms.
    • Tumor cells are embedded in a fibrous or myxoid stroma.
  • Spindle cell carcinoma
    • Sarcomatoid carcinoma composed only of spindle-shaped tumor cells.
  • Giant cell carcinoma
    • Sarcomatoid carcinoma composed only of anaplastic, giant tumor cells.
  • Carcinosarcoma
    • A mixture of carcinoma and true sarcomas such as osteosarcoma, chondrosarcoma or rhabdomyosarcoma.
    • The carcinoma component may be squamous cell carcinoma, adenocarcinoma, adenocarcinoma mixed with squamous cell carcinoma, and large cell carcinoma, whereas the sarcoma component may be rhabdomyosarcoma, osteosarcoma mixed with chondrosarcoma, and osteosarcoma.
  • Pulmonary blastoma
    • A biphasic tumor composed of a primitive epithelial component with well-differentiated, fetal adenocarcinoma and a primitive mesenchymal stroma that may contain rhabdomyosarcoma, osteosarcoma, or chondrosarcoma.