Differential Diagnosis for Movable Lump under Breast by Rib

• Single most likely diagnosis
  • Lipoma: A benign tumor composed of fat tissue, which is often movable and can be found in various parts of the body, including under the breast near the rib cage. Its mobility and location make it a common diagnosis for lumps in this area.
• Other Likely diagnoses
  • Sebaceous cyst: A benign, usually movable, lump under the skin that can occur anywhere, including under the breast. It is filled with a cheesy, semi-solid material.
  • Fibroadenoma: Although more commonly found within the breast tissue, a fibroadenoma can occasionally present as a movable lump near the breast, especially if it is located near the edge of the breast tissue.
  • Breast cyst: While typically within the breast, a large cyst could potentially feel like it's under the breast if it's located near the periphery.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Breast cancer: Although less likely to be highly movable, certain types of breast cancer (like inflammatory breast cancer or a large tumor) could potentially present as a lump under the breast. Given the potentially severe consequences, it's crucial not to miss this diagnosis.
  • Lymphoma: Enlarged lymph nodes due to lymphoma could be felt under the breast near the rib cage, especially if the lymph nodes in the axillary (armpit) region are involved.
• Rare diagnoses
  • Hamartoma: A rare, benign tumor that can occur in the breast or surrounding tissue, which might feel like a movable lump.
  • Phyllodes tumor: Although usually within the breast, a large phyllodes tumor could potentially be felt under the breast if it's located near the edge of the breast tissue. These tumors are rare and can be either benign, borderline, or malignant.
  • Metastasis: In rare cases, a metastatic tumor from another primary cancer could present as a lump under the breast, especially if it involves the lymph nodes or soft tissues in that area.