Pancoast tumor is the type of lung cancer that is associated with invasion of the apical chest wall. The location of Pancoast tumor in the superior sulcus results in an invasion of adjacent structures and in its characteristic clinical presentation. The progression of Pancoast tumor usually involves spread across the pleural apex to invade the following structures by direct extension into lymphatic vessels in the endothoracic fascia, intercostal nerves, lower roots of brachial plexus, stellate ganglion, sympathetic chain, adjacent ribs, adjacent vertebra bodies, extension to the spinal cord can result in cord compression, subclavian artery or subclavian vein. The development of Pancoast syndrome is the result of tumors in the superior pulmonary sulcus is characterized by pain along ulnar nerve distribution and Horner’s syndrome.

• Pancoast tumor is the type of lung cancer that is associated with invasion of the apical chest wall. The location of Pancoast tumor in the superior sulcus results in an invasion of adjacent structures and in its characteristic clinical presentation.^[1][2][3][4]
• The progression of Pancoast tumor usually involves spread across the pleural apex to invade the following structures by direct extension:
  • Lymphatic vessels in the endothoracic fascia
  • Intercostal nerves
  • Lower roots of brachial plexus
  • Stellate ganglion
  • Sympathetic chain
  • The first, second, or third rib
  • First or second thoracic vertebra bodies or intervertebral foramina
  • Extension to the spinal cord can result in cord compression
  • Subclavian artery
  • Subclavian vein
• The development of Pancoast syndrome is the result of tumors in the superior pulmonary sulcus is characterized by pain along ulnar nerve distribution and Horner’s syndrome.

• On gross pathology, findings will depend on the histological subtype of Pancoast tumor.
• Lung adenocarcinoma gross pathology findings, include:^[5]

• Spherical tumor with well-defined borders
• Homogeneous gray-white cut surface
• Involvement of the thoracic wall
• Usually found in the peripheral lung

• Large cell lung cancer gross pathology findings, include:^[5]

• Well-defined borders
• Resemblance to gross findings in adenocarcinoma
• No signs of anthracosis
• Involvement of the thoracic wall

• Squamous cell lung cancer gross pathology findings, include:^[5]

• Lung mass
• Usually centrally located
• Associated with a large airway
• Usually have a central cavitation

On microscopic pathology, findings will depend on the histological type of Pancoast tumor.^[5]

• Lung adenocarcinoma microscopic pathology findings, include:

• Nuclear atypia
• Eccentrically placed nuclei
• Abundant cytoplasm with mucin vacuoles
• Often conspicuous nucleoli
• Lack of intercellular bridges.
• Different patterns, include: acinar, lepidic, micropapillary, papillary, and solid.

• Large cell lung cancer microscopic pathology findings, include:

• Large polygonal cells and anaplastic cells
• No squamous or glandular differentiation
• Moderately abundant cytoplasm
• Vesicular nuclei, prominent nucleoli

• Squamous cell lung cancer microscopic pathology findings include:

• Central nucleus
• Dense appearing cytoplasm, usually eosinophilic
• Small nucleolus
• Intracellular bridges (classic feature)

On immunohistochemistry, the findings depend on the histological type of Pancoast tumor.^[6][5]

• Common immunohistochemistry markers used for Pancoast tumor subtyping, include:

• TTF-1 for adenocarcinoma
• p63 and high-molecular-weight keratins for squamous cell carcinoma
• Lack of staining with neuroendocrine markers (chromogranin A, synaptophysin, and CD56)