November 10-15

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ACR Convergence 2023

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Clinicopathologic Conference shows route to GPA diagnosis


3 minutes

Every year, the ACR presents a Clinico-pathologic Conference at the Annual Meeting that features difficult-to-diagnose case studies of rheumatologic patients and takes the audience through the step-by-step process of a differential diagnosis and the twists and turns of the patient’s course to arrive at a final diagnosis.

This year’s conference spotlighted the case of a 50-year-old French-born Caucasian male with no past medical history who presented with migratory polyarthritis.

Matt Cascino, MD

Matt Cascino, MD, a rheumatology fellow at the University of California, San Francisco, presented the raw data of the case, and Andrew Gross, MD, Associate Professor of Medicine and Rheumatology Clinic Chief at UCSF, discussed the differential diagnosis and the various steps taken to arrive at the correct diagnosis.

“Three months prior to presentation, the patient awoke from sleep with severe pain in the right shoulder during travel to Tahiti. Shoulder pain lasted for two days, then resolved,” Dr. Cascino said. “After returning to the United States, he noted arthritis sequentially affecting the ankles, knees, wrists, and fingers. Arthritis lasted for one to two days in each joint and returned to normal between episodes.”

When considering migratory arthritis, Dr. Gross said, clinicians think about inflammatory disease in the differential diagnosis.

Andrew Gross, MD

“In trying to narrow the diagnosis, we thought that these attacks were not actually migratory arthritis,” he said. “They were really migratory acute attacks of monoarthritis, or palindromic rheumatism.”

Palindromic rheumatism typically resolves within two days or less, and subsequent attacks often involve other joints. It is sometimes associated with the development of rheumatoid nodules, Dr. Gross said. A chest x-ray showed a 2.3 cm nodule in the right lung, and a chest CT exam revealed irregular pulmonary nodules. A CT of the pelvis showed pancolitis.

With symptoms of colitis and pulmonary nodules, the two physicians began to think of Crohn’s disease. The patient underwent flexible sigmoidoscopy, colonic biopsy, bronchoscopy, an ophthalmic exam, and urine studies.

Other diagnostic tests showed the presence of anti-proteinase 3 (PR3) antibody 129. This result was consistent with a diagnosis of granulomatosis with polyangiitis (GPA), the final diagnosis.

In the hospital, the patient was given methylprednisolone and a renal biopsy. He subsequently developed acute abdominal pain and underwent an exploratory laparoscopy emergently. After he recovered from surgery, the patient was given 1000mg of rituximab intravenously for induction treatment of GPA followed by a glucocorticoid taper.

On follow-up exam at six weeks after discharge, he complained of fevers, chills, night-sweats, and fatigue. He was readmitted, and inpatient evaluations showed that the clinical features of GPA had resolved.

“When someone comes back to the hospital with the symptoms this patient had, my natural inclination is to think he has developed an opportunistic infection. So we went through a considerable workup to identify the opportunistic infection,” Dr. Gross said. “We realized that anyone treated for GPA should really be also treated with PCP (pneumocystis carinii pneumonia) prophylaxis. A French study showed that people with GPA have one of the highest rates of PCP among all the diseases they looked at, even surpassing that of acute and chronic leukemias.”

He said that his team’s practice was to give PCP prophylaxis for at least 6 months following treatment with rituximab in patients with severe GPA.

At follow up, Dr. Gross said, the patient was doing “extremely well” and remained in clinical remission.