Differential Diagnosis for Hard Mobile Mass on Shoulder
- Single most likely diagnosis
- Lipoma: A benign tumor composed of fat tissue, lipomas are common, mobile, and can occur on the shoulder. They are usually painless and can grow to be quite large.
- Other Likely diagnoses
- Cyst (e.g., sebaceous cyst, epidermoid cyst): These are benign, fluid-filled sacs that can form on the skin, including the shoulder area. They can be mobile and hard, depending on their composition and the presence of any inflammation.
- Fibroma: A benign tumor of fibrous connective tissue, fibromas can be found on the skin and can present as hard, mobile masses.
- Adipocytic tumors (e.g., angiolipoma, spindle cell lipoma): These are variants of lipomas with different cellular compositions and can also present as hard, mobile masses on the shoulder.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Metastatic tumor: Although less common, a hard mobile mass on the shoulder could potentially be a metastasis from a primary cancer elsewhere in the body. This would be particularly concerning in patients with a known history of cancer.
- Sarcoma (e.g., soft tissue sarcoma): These are rare, malignant tumors that arise from connective tissue. They can present as hard masses and, although uncommon, are critical to diagnose early due to their potential for aggressive behavior and poor prognosis if not treated promptly.
- Rare diagnoses
- Dermatofibrosarcoma protuberans (DFSP): A rare skin cancer that typically presents as a firm, hard mass that can be mobile. It has a tendency to recur locally if not completely excised.
- Pilomatrixoma: A rare, benign tumor of the skin that arises from the hair follicle matrix. It can present as a hard, mobile mass, often in the head and neck region, including the shoulder area.
- Neurofibroma: A benign nerve sheath tumor that can occur anywhere in the body, including the shoulder. It can present as a hard, mobile mass, especially in the context of neurofibromatosis type 1 (NF1).