Case Report Coexistent Pseudogout and Mycobacterium avium-intracellulare Septic Arthritis in a Patient with HIV and ESRD Wais Afzal, Omer M. Wali, Kelly L. Cervellione, Bhupinder B. Singh, and Farshad Bagheri Departments of Internal Medicine and Clinical Research, Jamaica Hospital Medical Center, 8900 Van Wyck Expressway, Jamaica, NY 11418, USA Correspondence should be addressed to Wais Afzal; wais.afzal@gmail.com Received 18 May 2016; Revised 28 August 2016; Accepted 19 September 2016 Academic Editor: Jamal Mikdashi Copyright © 2016 Wais Afzal et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Pseudogout is a crystal-induced arthropathy characterized by the deposition of calcium pyrophosphate dihydrate (CPPD) crystals in synovial fuid, menisci, or articular cartilage. Although not very common, this entity can be seen in patients with chronic kidney disease (CKD). Septic arthritis due to Mycobacterium avium-intracellulare (MAI) is a rare entity that can afect immunocompromised patients such as those with acquired immunodefciency syndrome (AIDS) or those who are on immunosuppressive drugs. Here, we describe a 51-year-old female who presented with fever, right knee pain, swelling, warmth, and decreased range of motion for several days. Te initial assessment was consistent with pseudogout, with negative bacterial and fungal cultures. However, due to high white blood cell (WBC) count in the synovial fuid analysis, she was empirically started on intravenous (IV) vancomycin and piperacillin-tazobactam and discharged on IV vancomycin and cefepime, while acid-fast bacilli (AFB) culture was still in process. Seventeen days later, AFB culture grew Mycobacterium avium-intracellulare (MAI), and she was readmitted for relevant management. Tis case illustrates that septic arthritis due to MAI should be considered in the diferential diagnosis of septic arthritis in immunocompromised patients. 1. Introduction Patients with CKD are prone to develop various articular pathologies including osteodystrophy, osteonecrosis, dialy- sis-related amyloidosis, septic arthritis, malignancy, and crys- tal-induced arthropathies [1]. Pseudogout is a crystal-in- duced arthropathy characterized by the deposition of CPPD crystals in synovial fuid, menisci, or articular cartilage. Te likely mechanism behind pseudogout in CKD is secondary hyperparathyroidism, which is due to increased resistance to the parathyroid hormone (PTH) [2]. Joint aspiration and observation of positively birefringent rhomboid-shaped crystals under polarized light microscopy will establish the diagnosis. Septic arthritis due to MAI is a rare entity that most commonly occurs in immunocompromised patients such as advanced human immunodefciency virus (HIV) patients or those who are on immunosuppressive drugs [3–5]. In advanced HIV patients, MAI infection typically develops in generalized fashion; however, rarely isolated bone and joint infection can occur [3]. MAI-related septic arthritis results from percutaneous inoculation or hematogenous seeding [4]. Clinical history and physical examination, as well as basic lab work, raise suspicion; nevertheless, defnitive diagnosis is established by the joint aspiration, biopsy, and microbiologic cultures. Polymerase chain reaction (PCR) is also consid- ered as an adjuvant diagnostic modality [6]. Treatment in the majority of cases consists of surgical debridement and antimycobacterial drugs [6]. According to our knowledge, this is the frst case illustrat- ing coexistent pseudogout and MAI arthritis to be reported in the literature. Here, we present a case of a patient with advanced HIV infection on highly active antiretroviral ther- apy (HAART) with end-stage renal disease (ESRD) on he- modialysis who presented with fever, right knee joint pain, swelling, warmth, and stifness. She was ultimately found to have culture-proven MAI arthritis. Hindawi Publishing Corporation Case Reports in Rheumatology Volume 2016, Article ID 5495928, 4 pages http://dx.doi.org/10.1155/2016/5495928