FREQUENTLY, PATIENTS see their doctors bringing their chest X-ray plates showing a “spot” in their lungs. Also called a “coin” lesion by doctors, a “spot” is a solitary lung nodule which is round or oval, as seen with a chest X-ray or CT scan. The common lay impression of a “spot” in the lungs is that it’s due to tuberculosis (TB). But these “spots” in the lungs on X-ray or CT scan could range from anything benign to something potentially life-threatening such as lung cancer.
Dr. Allison R. Quicoy or Dr. Allicoy—as friends fondly call her—from the University of the Philippines College of Medicine, wrote for the October issue of H&L magazine an interesting and informative article on how to go about evaluating patients presenting with a “coin” lesion or a solitary pulmonary nodule (SPN). A thorough evaluation of these patients is imperative so as to come up with the proper course of action in treating them.
Less than 3 cm
A “coin” lesion is generally less than three centimeters in greatest diameter. It is usually surrounded by normal lung tissues with no other significant findings on X-ray like collapse of parts of the lungs (atelectasis) or enlargement of the lymph nodes. “Many patients come to their doctors complaining of an abnormal chest X-ray with no other symptoms or complaints, just a “spot” on a routine X-ray that may have cost the patient his or her job, or may have caused sleepless nights due to anxiety,” Allicoy writes.
Allicoy explains that majority of coin or solitary pulmonary nodules (SPNs) are benign or noncancerous, caused by a variety of conditions such as TB, benign tumors, infections, swelling, and rarely, autoimmune disorders such as Lupus, and blood-vessel abnormalities. “However, a significant percentage (30–40 percent) of SPNs are still malignant or cancerous in nature,” Allicoy warns, “most commonly primary lung cancer, carcinoid tumors, or metastatic tumors from other sites.” Twenty to thirty percent of primary lung cancers initially present as SPNs.
Even in the absence of other sophisticated laboratory exams, the chest X-ray can be very informative in assessing a coin lesion. The radiologist evaluates the characteristics of the SPN including size, regularity of the border and the presence of calcifications.
Small nodules, which are less than 2 cm in diameter, are generally benign. SPNs bigger than 3 cm have a higher risk of being cancerous. The size, however, has to be correlated with other features as there are SPNs which are small but could turn out to be malignant or cancerous.
Benign SPN
Allicoy describes the benign SPN: “They have well-circumscribed, smooth borders, while irregular, lobulated, or spiculated borders, which imply uneven growth, are associated with malignant tumors.” She cites a study which has shown that the presence of irregular borders was associated with a fourfold increase in the likelihood of malignancy. It is not unusual, however for cancerous nodules to also present with smooth contours.
The presence of calcifications suggests more a benign nature of the coin lesion. A thin-walled cavity (less than 1 mm) also suggests a benign lesion, “while a thick-walled cavity may represent either a benign or malignant disease,” Allicoy explains.
Sometimes, what appears to be a coin lesion in the lungs on X-ray is actually located outside the lungs; on a frontal view of the X-ray, it just looks like it’s part of the lungs. Examples of this would be a rib fracture or even a thickened skin lesion on the chest or back. The doctor then requests for a lateral or side view of the X-ray or a CT scan which is a lot more sensitive in delineating the structure and location of the SPN. The CT scan can give additional information to differentiate a cancerous from a noncancerous SPN.
In some cases, Allicoy says a serial or repeat chest X-ray or CT scan may need to be done.
Cancerous SPNs can double their size within days to months. If it does not increase in size or takes more than a year or two to double its size, an SPN is likely to be benign.
PET
Some modern medical centers in the country offer a positron-emission tomography (PET) scan to assess the activity of tissues including SPNs. It uses a glucose analogue 18-F-2 fluorodeoxyglucose (FDG) to determine the metabolic activity of tumors. “Malignant nodules have increased glucose consumption compared with benign lesions and healthy tissues, and hence show higher FDG uptake values,” Allicoy explains.
She adds though that false-positives may occur with other metabolically-active pulmonary nodules such as infectious or inflammatory nodules, and it may not be able to detect small malignant lesions which are less than 2 cm.
When the attending physician is still not sure of the nature of an SPN, he may choose additional tests which may include a needle aspiration biopsy of the SPN guided by ultrasound or CT scan. Sometimes, the surgeon may be called in to operate on the patient and excise the coin lesion, or do a more extensive surgery if it turns out to be cancerous.
“If a patient with a pulmonary nodule is with an intermediate probability (50-60 percent) of having cancer, a biopsy is the best initial diagnostic procedure,” Allicoy advises. “However, in lesions with a high probability of malignancy, surgical resection instead of a biopsy is optimal.”
So, if you’ve got a “coin” in your lungs, it’s best to consult your physician to determine if it’s benign or malignant “currency.” Keeping rare coins may be a good form of investment, but definitely not this one.