Differential Diagnosis for Patient with Ankylosing Spondylitis on Talz Presenting with Mass at the Right Posterior Lateral Rib Cage

• Single Most Likely Diagnosis
  • Rib fracture or stress fracture: Given the patient's history of ankylosing spondylitis, which increases the risk of osteoporosis and fractures, a mass at the right posterior lateral rib cage could be indicative of a fracture, especially if the patient has experienced recent trauma or has been on long-term corticosteroids like Talz (which could be a typo and might refer to a medication such as Taltz, used for psoriasis and psoriatic arthritis, or more likely, a TNF-alpha inhibitor used in the treatment of ankylosing spondylitis).
• Other Likely Diagnoses
  • Costochondritis or Tietze's syndrome: Inflammation of the cartilage that connects the ribs to the breastbone could present as a mass or swelling in the rib cage area, especially if the patient has been experiencing chest pain or tenderness.
  • Soft tissue tumor (benign): A benign tumor such as a lipoma or a fibroma could present as a mass in the rib cage area.
  • Infection or abscess: Although less common, an infection or abscess in the soft tissues of the rib cage could present as a mass, especially if the patient has signs of infection such as fever or redness.
• Do Not Miss Diagnoses
  • Lung cancer: Given the proximity of the mass to the lung, lung cancer must be considered, especially in patients with a history of smoking or other risk factors.
  • Lymphoma: A mass in the rib cage area could be indicative of lymphoma, particularly if the patient has systemic symptoms such as weight loss or night sweats.
  • Osteomyelitis: An infection of the bone could present as a mass or swelling in the rib cage area and is a critical diagnosis not to miss due to its potential for serious complications.
• Rare Diagnoses
  • Ewing's sarcoma or other primary bone tumors: Although rare, primary bone tumors such as Ewing's sarcoma could present as a mass in the rib cage area.
  • Metastatic disease to the rib: If the patient has a history of cancer, metastasis to the rib could present as a mass.
  • Amyloidosis: In rare cases, amyloid deposits can accumulate in the soft tissues or bones, potentially presenting as a mass, although this would be an uncommon presentation.