Pancoast tumor is
**Core Concept:** Pancoast tumor is a type of lung cancer that arises from the superior lobe of the lung, specifically the posterior superior lobe. It is named after Dr. Thomas Pancoast, who first described this condition in 1935. Pancoast tumors can compress adjacent structures, leading to various symptoms.
**Why the Correct Answer is Right:**
Pancoast tumors are a group of neoplasms that originate from the upper lobe of the lung, typically the posterior superior lobe. They can grow in three dimensions, compressing adjacent structures such as the brachial plexus, subclavian vein, and the thoracic duct. This compression leads to characteristic symptoms, including pain radiating to the supraclavicular fossa, arm, and shoulder, as well as motor and sensory deficits involving the C8 and T1 roots of the brachial plexus.
**Why Each Wrong Option is Incorrect:**
A) Option A (Supraclavicular lymph node enlargement) is incorrect because Pancoast tumors primarily affect the brachial plexus and spinal cord, rather than lymph nodes.
B) Option B (Chest wall deformity or pleural effusion) is not the primary feature of Pancoast tumors. These tumors primarily affect the brachial plexus and spinal cord, causing symptoms rather than appearing as a physical sign.
C) Option D (Lymph node enlargement) is not the primary feature of Pancoast tumors. As mentioned earlier, these tumors primarily affect the brachial plexus and spinal cord, causing symptoms rather than appearing as a physical sign.
**Clinical Pearl:**
Pancoast tumors are often mistaken for other conditions, such as cervical ribs, subclavian vein thrombosis, or brachial plexopathy. A high index of suspicion is required for diagnosis, as the symptoms often overlap with those of other conditions. Thoracic radiograph, CT or MRI scans of the chest, and nerve conduction studies can aid in the diagnosis.
**Correct Answer:** D. Lymph node enlargement (Option D) is the correct answer because the tumor can cause lymph node enlargement as a secondary manifestation. This is due to the tumor compressing the brachial plexus, leading to the production of cytokines and secondary lymphadenopathy.