Pain experienced in or around the shoulder blade (scapular pain) is a common complaint. While cancer can cause pain in this region, the vast majority of cases are not due to malignancy. The pain most often stems from mechanical issues in the muscles and joints or is referred from non-cancerous internal organ systems. Understanding the less common, serious causes is important for knowing when to seek professional medical evaluation.
Common Musculoskeletal Sources of Pain
The most frequent origin of pain between or beneath the shoulder blades is a localized musculoskeletal problem. This pain often results from muscle strain, particularly involving the rhomboids and trapezius muscles, which stabilize and move the scapula. Activities like heavy lifting, repetitive arm movements, or poor sleeping positions can lead to micro-tears or spasms.
Poor posture, sometimes termed “tech neck,” is a prevalent modern cause. A forward head and rounded shoulder position places chronic strain on the upper back musculature. This sustained tension causes a deep, aching sensation that worsens throughout the day, especially when sitting for long periods. The pain is typically aggravated by specific movements or static positions and is relieved by rest or changing posture.
Mechanical dysfunction of the shoulder girdle, such as scapular dyskinesis, also contributes to localized pain. This condition involves an alteration in the normal position of the scapula during movement, often due to muscle weakness or imbalance. The abnormal motion can irritate surrounding soft tissues, leading to discomfort perceived as being under the shoulder blade.
Irritation to the rotator cuff tendons or bursitis in the shoulder joint can cause discomfort that radiates backward toward the scapula. Although the primary issue is in the shoulder joint, surrounding nerves transmit the pain signal to the upper back. In these common cases, the pain is usually reproducible by physical examination and directly related to activity or position.
Referred Pain from Internal Systems
Pain felt near the shoulder blade can be referred pain, originating from an organ or structure separate from the perceived location. The thoracic spine is a frequent source of referred pain due to issues like nerve compression from a herniated disc or facet joint arthritis. This pain often presents as a sharp, burning sensation that may be accompanied by tingling or numbness radiating along a nerve path.
Conditions affecting the thoracic cavity, such as pleurisy (inflammation of the lining surrounding the lungs), can cause sharp pain felt in the upper back or shoulder blade area. This occurs due to shared nerve pathways between the pleural lining and the sensory nerves of the shoulder. Pulmonary issues can therefore mimic a muscle strain.
Digestive and abdominal issues are a significant source of referred scapular pain. Gallbladder disease, particularly gallstones, commonly causes pain that radiates to the right shoulder blade, especially after eating fatty foods. Similarly, peptic ulcers or irritation of the diaphragm from severe acid reflux can cause pain referred to the left shoulder blade due to phrenic nerve irritation.
Cardiac conditions, such as a heart attack or angina, can present with pain that radiates to the left shoulder, neck, or between the shoulder blades. This referred pain pattern results from the complex way the nervous system processes pain signals from the chest. Shoulder blade pain combined with symptoms like shortness of breath or chest discomfort warrants immediate medical attention.
Understanding the Link to Cancer
While rare, cancer can cause shoulder blade pain, typically through three main mechanisms: direct invasion, bone metastasis, or nerve compression. The location of the pain often raises suspicion for malignancy, as tumors in the upper chest or spine can directly affect nearby nerves and bones.
Lung cancer, specifically a Pancoast tumor, is a recognized cause of shoulder blade pain. These tumors develop in the apex of the lung and can invade surrounding structures, including the upper ribs and the brachial plexus (a network of nerves supplying the shoulder and arm). This invasion often results in intense, sharp shoulder pain that radiates down the arm, frequently presenting as the first symptom.
The scapula and surrounding spine are common sites for bone metastasis (the spread of cancer from a primary tumor elsewhere). Cancers that frequently metastasize to the bone (such as breast, lung, and prostate cancer) can cause destructive lesions that weaken the bone structure. This bone involvement leads to a deep, persistent, and dull ache in the shoulder blade region that is unrelated to movement or position.
Cancer-related pain is typically constant, progressive, and may worsen at night, often disrupting sleep. Unlike musculoskeletal pain, which usually improves with rest, this type of pain is not relieved by common pain relievers or positional changes. Primary bone cancers, such as sarcoma, can also originate in the scapula, presenting as a mass and causing pain that gradually increases in severity.
Diagnostic Steps and Urgent Symptoms
When shoulder blade pain is persistent, a medical evaluation is warranted to differentiate between benign and serious causes. A physician will begin with a thorough physical examination, assessing the range of motion, muscle strength, and palpating the area to see if the pain can be reproduced by movement. This is followed by a detailed history, focusing on the quality of the pain, alleviating factors, and associated symptoms.
Certain accompanying symptoms, often called “red flags,” increase the urgency of the medical consultation and raise suspicion for a systemic illness like cancer. These symptoms include:
- Unexplained and significant weight loss.
- Night sweats.
- A persistent fever that cannot be attributed to an infection.
- Pain that is constant and fails to improve with rest, physical therapy, or over-the-counter pain medication.
Neurological changes, such as new weakness, numbness, or tingling in the arm or hand, suggest nerve involvement that requires prompt investigation. The diagnostic process often involves imaging studies, beginning with X-rays to visualize the bones and look for signs of a tumor or bone erosion. If the X-ray is inconclusive, advanced imaging like a CT scan or MRI may be ordered to better view soft tissues and the spine.