An unusual mimic for arthritis

The differential diagnosis for polyarticular arthritis is long, including autoimmune arthritis, infections, cancer, drug reactions, osteoarthritis and crystal arthritis. Sometimes we have to think outside the joint! Tiffany (name changed) is a 69-year-old retired schoolteacher living in Vancouver. She has been mostly healthy other than having had breast cancer in her 40s, which was treated with surgery, chemotherapy and radiation therapy. Though her treatments were certainly life-saving, she did suffer some iatrogenic harm from them, including osteoporosis, peripheral neuropathy, and a deep venous thrombosis (DVT). She leads a healthy lifestyle. I have been her family doctor since mid-2023.She consulted me in late 2023 regarding six weeks of mild pain and swelling in the hands, mainly around the proximal interphalangeal and metacarpophalangeal joints. This followed two weeks after a mild gastroenteritis. Other than some mild swelling and tenderness, the examination of her hands was normal. A radiograph was normal. Her C-reactive protein was 6.7 mg/L (normal is less than 5, though hers is slightly elevated at baseline). Anti-cyclic citrullinated peptide antibodies and rheumatoid factor were below the threshold of detection.Read: Case report: Infected?I diagnosed her with reactive arthritis provoked by gastroenteritis and prescribed a non-steroidal anti-inflammatory drug (NSAID), which helped somewhat. She had a personal connection to a rheumatologist who agreed to see her, and I obliged to consult him. The rheumatologist ordered additional laboratories, which were negative, including antinuclear antibodies and human leukocyte antigen B27. He agreed that this was reactive arthritis, and prescribed a different NSAID, which helped her symptoms, though the symptoms nevertheless persisted.In the following months, Tiffany consulted me over a number of problems. Her peripheral neuropathy became harder to control, and she asked for compression stockings, which had helped in the past. Her internist started her on gabapentin for these symptoms, and she reported weight gain of about 2 kg and some ankle edema as side-effects of gabapentin. Her feet started feeling stiff, and her rheumatologist and I both suspected this was due to osteoarthritis of the feet, though radiographs were fairly normal. She complained that her right leg—the same side as the DVT—felt “heavy” when hiking, that it “felt as if (she) was dragging a piece of lumber up the hill” and that it “doesn’t feel like (her) leg.” She has had some degree of post-thrombotic syndrome in that leg for many years, but this was worse than usual. Her extremities were examined and were normal other than mild edema. I did an ankle-brachial index in my office, which was 0.91 in the right ankle and 1.00 in the left (1.0–1.4 is normal, 0.91–0.99 is borderline).In mid-2024, Tiffany came to me concerned about getting winded more easily than usual, no longer being able to keep up with her friends when hiking. This had progressed over the past several months. She reported that her resting heart rate had risen to the 60s (previously it had been in the 50s), and that she had occasional palpitations when lying on her left side. She had no other respiratory or cardiologic symptoms, and her lung and precordial examinations were normal. A chest X-ray and spirometry did not clarify the cause. An electrocardiogram found a left axis deviation and a right bundle branch block. Laboratories were not significant other than a prohormone B-type natriuretic protein of 1820 ng/L (normal is less than 125).I suspected her breathlessness was due to heart failure. Given her history, the most likely diagnosis was a delayed presentation of cardiomyopathy caused by chemotherapy or radiation. I started her on a trial of a low dose of furosemide and ordered an echocardiogram, which found severe dilation of the left ventricle with a left ventricular ejection fraction of 48%, as well as diastolic dysfunction.I followed up with her during the trial of furosemide, and after about a week, she noticed improvement in her breathlessness, as expected. Surprisingly, she also noticed a marked improvement in her hand pain. Her weight returned to normal, her “heavy” leg had resolved, and her many peripheral symptoms attributed variously to worsening neuropathy, osteoarthritis, and gabapentin side effects had greatly improved. As it happens, I believe the “reactive arthritis” and all these other conditions were mimicked by volume overload and peripheral edema caused by congestive heart failure.I referred her to a cardiologist, who ordered an exercise stress test (which was equivocal) and myocardial perfusion testing (which was normal). He agreed she had heart failure caused by her cancer treatments. He ordered left ventricular enhancing therapies and her symptoms, respiratory and otherwise, continued to improve.Dr. Nicholas Steinberg is a GP in Vancouver.

An unusual mimic for arthritis

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