Disclosures: Evan M. Berlin, MD: No financial relationships or conflicts of interest

Case Description: This case describes an inflammatory arthritis that was initially suspected to be rocky mountain spotted fever (RMSF), then pseudogout after arthrocentesis, but was ultimately diagnosed as reactive arthritis from a genitourinary chlamydia infection.

Setting: Inpatient

Patient: 39-year-old male with no pertinent past medical history who presented to the emergency department with polyarticular arthralgia to the left ankle, left elbow, bilateral knees, hands and wrist for one week. A tick was found on the patient’s back that was photographed and identified as an American Dog Tick, a known vector for RMSF. He was empirically started on doxycycline and was admitted to the hospital due to gait and ADL dysfunction secondary to polyarticular arthralgia. Assessment/

Results: The patient did not improve on the doxycycline. His left knee became erythematous and tender to palpation. Arthrocentesis was performed and fluid analysis revealed 15,000 WBC, no organisms, and calcium pyrophosphate dihydrate crystals. A diagnosis of pseudogout was made and the patient was started on oral prednisone and ibuprofen. Unfortunately, the patient had minimal symptom relief. A gonorrhea and chlamydia PCR was sent on initial workup after the patient revealed he engaged in unprotected sex with multiple partners. On hospitalization day four, the PCR resulted as positive for chlamydia. The patient was given a one-time dose of azithromycin with nearly complete resolution of his symptoms within 48 hours.

Discussion: A broad differential must be considered when evaluating a patient with polyarticular arthralgia. This patient had risk factors and findings that were consistent with multiple etiologies. A thorough workup was performed including history taking, physical exam, and diagnostic testing. Ultimately, the correct diagnosis and appropriate treatments were given.

Conclusion: This case aims to review the work-up and treatment of polyarticular arthralgia related to tick-borne illnesses, crystal induced arthropathies, and reactive arthritis.

Level of Evidence: Level IV

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/reactive-arthritis-masquerading-as-rocky-mountain-spotted-fever-and-pseudogout/