Differential Diagnosis
- Single most likely diagnosis
- B) Fibromyalgia: This is the most likely diagnosis due to the patient's presentation of constant, severe pain in the neck, shoulders, and back for 3 months, multiple tender spots over these areas, and a history of irritable bowel syndrome. The absence of synovitis, negative fluorescent serum antinuclear antibody, and rheumatoid factor assays also support this diagnosis, as fibromyalgia is characterized by widespread musculoskeletal pain without evidence of inflammatory arthritis.
- Other Likely diagnoses
- E) Seronegative rheumatoid arthritis: Although less likely, seronegative rheumatoid arthritis could be considered due to the patient's complaint of pain in multiple areas. However, the absence of synovitis and negative rheumatoid factor make this less likely.
- C) Polymyalgia rheumatica: This condition typically presents with stiffness and pain in the shoulders and hips, but it is more common in older adults, making it less likely in this 24-year-old patient.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Infections (e.g., osteomyelitis, discitis): Although not directly suggested by the patient's presentation, it's crucial to consider infectious causes of back and neck pain, as they can be severe and require prompt treatment.
- Malignancy (e.g., multiple myeloma, metastatic cancer): While rare in a young patient, malignancy can cause widespread pain and should be considered, especially if the patient's condition does not improve with treatment for fibromyalgia.
- Rare diagnoses
- A) Ankylosing spondylitis: This condition is characterized by inflammatory back pain and stiffness, often with limited range of motion. However, the patient's full range of motion and lack of synovitis make this diagnosis less likely.
- D) Polymyositis: This is an inflammatory muscle disease that could cause muscle pain, but it typically presents with muscle weakness, which is not mentioned in the patient's presentation.