Finding a lump on top of your shoulder can be an unsettling experience. While many shoulder lumps are harmless and resolve on their own, understanding the various potential causes is important. Knowing when to seek professional medical advice is equally important for an accurate diagnosis and appropriate management.
Lumps Originating in Soft Tissues
Lumps on the shoulder often arise from the soft tissues, which include fat, muscles, and connective tissues just beneath the skin. These are frequently benign and may not require extensive treatment.
Lipomas
Lipomas are among the most common soft tissue tumors in adults, appearing as slow-growing, fatty lumps located just under the skin. They are typically soft, doughy, and movable when pressed. While generally painless, they can cause discomfort if they press on nearby nerves or blood vessels. They commonly appear on the shoulders, arms, chest, and back in individuals aged 40-60 years.
Cysts
Cysts, such as sebaceous cysts, are fluid-filled sacs that form when a sebaceous gland becomes blocked. They typically present as small, round or oval lumps that are firm but mobile under the skin. Cysts are usually non-cancerous and painless, though they can become tender, red, warm, or infected if they rupture or become inflamed.
Muscle knots
Muscle knots, scientifically termed myofascial trigger points, are tense, contracted areas within muscle fibers that can form painful nodules. These firm, tender areas commonly affect the back, shoulders, and neck, causing localized pain, stiffness, and sometimes referred pain. Muscle knots often result from overuse, poor posture, stress, or injury.
Fibromas
Fibromas are benign growths composed of fibrous tissue and can occur almost anywhere on or in the body. While many fibromas do not cause symptoms, some types, like elastofibroma dorsi, can appear in the subscapular area of the chest wall, potentially causing shoulder pain or a snapping sensation. Nuchal-type fibromas, a rare form, present as firm, poorly defined subcutaneous masses, though they are usually asymptomatic.
Lumps Related to Bones and Joints
Lumps on the shoulder can also be directly associated with the underlying bone and joint structures. These conditions involve changes to the skeletal system or its surrounding protective elements.
Bone spurs
Bone spurs, known medically as osteophytes, are extra bone growths that form around joints, often due to conditions like osteoarthritis or general wear and tear. In the shoulder, these bony projections commonly appear near the acromion or glenohumeral joint. While initially symptomless, they can cause pain, stiffness, and limited movement if they press on tendons, nerves, or soft tissues. They are particularly common in adults over 60.
Bursitis
Bursitis involves the inflammation of bursae, which are small, fluid-filled sacs that act as cushions to reduce friction between bones, tendons, and ligaments near joints. Shoulder bursitis, specifically subacromial bursitis, occurs when these sacs become irritated and inflamed, leading to pain, swelling, tenderness, and warmth in the affected area. This condition often results from overuse, injury, or underlying inflammatory conditions such as rheumatoid arthritis or gout.
Ganglion cysts
Ganglion cysts are fluid-filled masses that typically form near joints or tendons. In the shoulder, these cysts can originate from the joint capsule or tendon sheath, often appearing as soft, round, or oval lumps. While many shoulder ganglion cysts cause no pain, larger ones can compress surrounding nerves, leading to discomfort or weakness. They are commonly associated with underlying joint or tendon issues.
Osteochondromas
Osteochondromas are noncancerous bone growths that consist of both cartilage and bone, developing near the growth plates at the ends of long bones. They are the most common benign bone tumors, typically diagnosed in individuals between 10 and 30 years old, affecting the long bones of the leg, pelvis, or shoulder blade. Most osteochondromas are painless and do not cause symptoms unless they grow large enough to press on nerves or interfere with joint movement.
Lumps from Infections, Inflammation, and Rare Conditions
Some shoulder lumps stem from infections, inflammatory processes, or, in rare instances, more serious underlying conditions. These causes often present with distinct characteristics that warrant medical attention.
Infections
Infections can lead to the formation of abscesses, which are localized collections of pus. A shoulder abscess can manifest as a painful, red, warm, and swollen lump, often accompanied by systemic symptoms like fever and chills. These pus-filled cavities can develop from skin or soft tissue infections.
Swollen lymph nodes
Swollen lymph nodes are a common sign of the body’s immune response to infection. Lymph nodes can swell and become tender, painful lumps when they accumulate bacteria or diseased cells. While often related to common illnesses, persistently swollen lymph nodes, especially those above the collarbone, can sometimes indicate a more serious condition, including certain cancers.
Inflammatory conditions
Inflammatory conditions, such as rheumatoid arthritis, can sometimes lead to the development of rheumatoid nodules. These firm lumps typically form under the skin near affected joints, including the shoulders and elbows. Rheumatoid nodules are usually not painful or tender, but they can become so if they are near a nerve or become ulcerated. They are a sign of inflammation, commonly appearing in individuals with more severe forms of rheumatoid arthritis.
Malignant tumors
Malignant tumors, while less common, can also present as a lump on the shoulder. Soft tissue sarcomas, for instance, are rare cancers that form in the body’s soft tissues like muscle, fat, or fibrous tissue. These tumors often appear as a painless lump or swelling that grows slowly over months or years, but they can cause pain if they press on nerves or muscles. Bone cancers, such as osteosarcoma or chondrosarcoma, can also manifest as a lump in the shoulder bone, often accompanied by persistent pain that worsens over time, swelling, or even a weakened bone leading to fracture. Metastatic deposits, where cancer cells spread from a primary tumor elsewhere in the body to the shoulder, can also cause a noticeable lump, pain, swelling, and reduced mobility.
Knowing When to See a Doctor
While many shoulder lumps are benign and may resolve without intervention, it is important to seek medical evaluation for certain symptoms. Any new lump on the shoulder should be examined by a healthcare professional, especially if it persists beyond a few weeks.
When to Seek Medical Attention
Rapid growth of the lump
Increasing pain
Changes in color or texture
Warm to the touch
Immobile
Accompanied by fever, night sweats, or unexplained weight loss
Interferes with normal shoulder movement or causes significant discomfort
A medical professional can provide an accurate diagnosis through physical examination and, if necessary, further diagnostic tests.