Rheumatologic conditions and infections may imitate each other, often making diagnosis challenging. Therefore, it is imperative to obtain adequate histories and have a keen eye for these potentially confounding differential diagnoses. Immunosuppressants used in managing rheumatologic etiologies have detrimental consequences in undiagnosed underlying infections. Consequently, worsening symptoms with standard therapy should raise awareness to a different diagnosis.
Nontuberculous mycobacteria (NTM) are slow-growing organisms difficult to yield in culture. Initial negative synovial fluid stains and cultures when suspecting NTM infectious arthritis or tenosynovitis should not exclude the diagnosis if there is a strong clinical scenario. The identification of Mycobacterium marinum (M marinum) infection in the hand is of utmost importance given that delayed treatment may cause significant and even permanent disability.
We present the case of a 73-year-old male patient with progressively worsening right-hand tenosynovitis who was evaluated for crystal-induced and sarcoid arthropathies in the setting of negative synovial biopsy cultures but was subsequently diagnosed with M marinum infectious tenosynovitis after a second surgical debridement.
Case Presentation
A 73-year-old male patient with history of type 2 diabetes mellitus, hypertension, hyperlipidemia, hypothyroidism, bilateral knee osteoarthritis, obstructive sleep apnea, and posttraumatic stress disorder presented to the emergency department (ED) with right wrist swelling and pain for 4 days. The patient reported that he was working in his garden when symptoms started. He did not recall any skin abrasions or wounds, insect bites, thorn punctures, trauma, or exposure to swimming pools or fish tanks. Patient was afebrile, and vital signs were within normal range. On physical examination, there was erythema, swelling, and tenderness in the dorsum of the right hand and over the dorsal aspect of the fourth metacarpophalangeal joint (Figure 1). The skin was intact.
Symptoms had not responded to 7 days of cefalexin nor to a short course of oral steroids. Leukocytosis of 14.35 × 109/L (reference range, 3.90-9.90 × 109/L) with neutrophilia at 11.10 × 109/L (reference range, 1.73-6.37 × 109/L) was noted. Sedimentation rate and C-reactive protein levels were normal. Right-hand X-ray was remarkable for chondrocalcinosis in the triangular fibrocartilage. Right upper extremity magnetic resonance imaging (MRI) revealed diffuse inflammation in the right wrist and hand (Figure 2). There was no evidence of septic arthritis or osteomyelitis. Consequently, orthopedic service recommended no surgical intervention. Additionally, the patient had preserved range of motion that further indicated tenosynovitis, which could be medically managed with antibiotics, rather than a septic joint.
One dose of IV piperacillin/tazobactam was given at the ED, and he was admitted to the internal medicine ward with right hand and wrist cellulitis and indolent suppurative tenosynovitis. Empiric IV ceftriaxone and vancomycin were started as per infectious disease (ID) service with adequate response defined as a reduction of the swelling, erythema, and tenderness of the right hand and wrist. Differential diagnosis included sporotrichosis, nocardia vs NTM infection.
Interventional radiology was consulted for right wrist drainage. However, only 1 mL of fluid was obtained. Synovial fluid was sent for cell count and differential, crystal analysis, bacterial cultures, fungal cultures, and acid-fast bacilli (AFB) stains and culture. Neutrophils were 43% and lymphocytes were 57%. Crystal analysis was negative. Bacterial culture and mycology were negative. AFB stain and culture results were negative after 6 weeks. Based on gardening history and risk of thorn exposure and low suspicion for common bacterial pathogens, ID service switched antibiotics to moxifloxacin, minocycline, and linezolid for broad coverage to complete 3 weeks as outpatient. The patient reported significantly improved pain and handgrip with notable decrease in swelling. Nonetheless, 3 weeks after completing antibiotics, the right-hand pain recurred, raising concern for complex regional syndrome vs crystalline arthropathy.