Pancoast tumor


Pancoast tumor

Description, Causes and Risk Factors:

Any carcinoma of the lung apex causing the Pancoast syndrome by invasion or compression of the brachial plexus and stellate ganglion.

Pancoast tumors are a subset of lung cancers that invades the apical chest wall. Because of their location in the pleural apex, they invade adjoining tissue. Although various other tumors may produce a similar clinical presentation because of their location at the thoracic inlet, the most common cause is generally believed to be a bronchogenic carcinoma arising in or near the superior sulcus and invading the adjacent extrathoracic structures by direct extension. The location of the tumor, rather than its pathology or histology of origin, is significant in producing its characteristic clinical pattern.

Carcinomas in the superior pulmonary sulcus produce Pancoast syndrome, thus causing pain in the shoulder and along the ulnar nerve distribution of the arm and hand. These apical lung tumors tend to be locally invasive early. In the absence of metastases and regional nodal involvement, these apical cancers can be successfully treated.

Causes include lymphomatoid granulomatosis, vascular aneurysms, amyloid nodules, and cervical rib syndrome. Inflammatory pseudotumor (plasma cell granuloma), mycotic subclavian artery aneurysm, and carotid pseudoaneurysm in a child (caused by a hydatid cyst) have been reported.

Risk factors are similar for almost all lung cancers. They include prior prolonged asbestos exposure, exposure to industrial elements (eg, gold, nickel), smoking, and secondary smoke exposure.

Staging is determined by the location of the lesion and its metastases. The true Pancoast tumor is usually T3, which describes the extension of the tumor through the visceral pleura into the parietal pleura and the chest wall. Pancoast tumors are classified as T4 when mediastinal invasion, cervical invasion, or both have occurred. Peripheral metastases signal a poor prognosis, and surgery is contraindicated in such cases.

Overall, Pancoast tumors are much less common than other lung cancers, accounting for fewer than 5% of these cancers.

Symptoms:

The symptoms are typical of the location of the tumor in the superior sulcus or thoracic inlet adjacent to the eighth cervical nerve roots, the first and second thoracic trunk distribution, the sympathetic chain, and the stellate ganglion. Initially, localized pain occurs in the shoulder and vertebral border of the scapula. Pain may later extend along an ulnar nerve distribution of the arm to the elbow and, ultimately, to the ulnar surface of the forearm and to the small and ring fingers of the hand (C8). Pain is frequently relentless and unremitting, often requiring narcotics for relief. The patient usually supports the elbow of the affected arm in the hand of the opposite upper extremity to ease the tension on the shoulder and upper arm.

Infrequently, a patient with a Pancoast tumor may also have features of a paraneoplastic syndrome. Most of the metabolic manifestations are the result of the secretion of endocrine chemicals by the tumor. Manifestations encompass Cushing syndrome, excessive antidiuretic hormone secretion, hypercalcemia, myopathies, hematological problems, and hypertrophic osteoarthropathy. The presence of paraneoplastic syndromes does not connote unresectability, but most of these are associated with small cell cancer.

Diagnosis:

Diagnosis of Pancoast tumors is frequently delayed for two reasons. These tumors are less likely to have typical lung cancer symptoms, such as shortness of breath and coughing, and people often first see an orthopedic surgeon or neurologist for their symptoms. Pancoast tumors are also difficult to see on chest x-rays due to their location. A combination of CT scans and MRI (to look for nerve involvement) is often done, followed by a biopsy to confirm the diagnosis.

Diagnosis via bronchoscopy is less helpful because most of these tumors are peripherally located. The flexible scope is more useful than the rigid scope in obtaining bronchoscopic aspirates and brush biopsy specimens.

Mediastinoscopy is used for staging to delineate the metastases to mediastinal lymph nodes. Cervical mediastinoscopy is indicated for right pulmonary lesions; a Chamberlain procedure (left second interspace mediastinoscopy) is indicated for left pulmonary lesions. Generally, mediastinoscopy is performed if the lymph nodes appear larger than 1 cm in diameter on a CT scan because the accuracy of CT scan results for predicting metastatic involvement in enlarged lymph nodes is only 70%. Conversely, if the CT scan does not reveal any enlarged lymph nodes, the patient is deemed operable. If the nodes in the mediastinum are positive, the prognosis is poor. The exception to this rule is an upper lobe lesion with positive nodes on the right side of the trachea only. If these are internodal, spread is considered local, and the tumor may still be resectable.

Liver, bone, and brain scans are performed to determine the presence of any metastatic disease. Although more than 90% of patients can be correctly diagnosed based on clinical and radiological findings alone, open biopsy of the tumor for pathological validation may be performed through a supraclavicular incision. Results from a needle biopsy through the supraclavicular or posterior triangle are also successful in confirming the diagnosis and in delineating the cell type prior to treatment. Even though clinical diagnosis is relatively simple, performing a tissue biopsy is still necessary.

Treatment:

The treatment of a Pancoast tumor may differ from that of other types of non-small cell lung cancer (NSCLC). Its position and close proximity to vital structures (such as nerves and spine) may make surgery difficult. As a result, and depending on the stage of the cancer, treatment may involve radiation and chemotherapy given prior to surgery (neoadjuvant treatment).

Surgery may consist of the removal of the upper lobe of a lung together with its associated structures (subclavian artery, vein, branches of the brachial plexus, ribs and vertebral bodies), as well as mediastinal lymphadenectomy. Surgical access may be via thoracotomy from the back or the front of the chest and modifications.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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