Flexor Tenosynovitis in a Diabetic Dialysis Patient

The diagnosis is flexor tenosynovitis, supported by fusiform swelling, finger held in flexion, tenderness along the sheath, and pain with passive extension. This is a surgical emergency. I would start broad-spectrum intravenous antibiotics covering gram-positive organisms including methicillin-resistant Staphylococcus aureus, and gram-negative organisms given diabetes and renal failure, with doses adjusted for dialysis. I would not rely on oral cephalexin alone. I would take the patient to the operating room for open drainage through a Brunner or midlateral incision, open the sheath, obtain aerobic, anaerobic, fungal, and mycobacterial cultures, and leave the wound open with a drain. I would avoid using the arm with the dialysis graft for blood pressure cuffs, intravenous lines, or venipuncture, and coordinate with nephrology about dialysis timing and anticoagulation. Early hand therapy after drainage helps prevent stiffness.

Diabetes and end-stage renal disease increase the risk of atypical and resistant organisms, including methicillin-resistant Staphylococcus aureus, gram-negative bacilli, and fungi. A thorn prick raises the possibility of plant-associated organisms such as Sporothrix, Nocardia, or mycobacteria, especially if the course is indolent. I would broaden coverage beyond a first-generation cephalosporin and obtain tissue rather than superficial swab cultures, because superficial cultures may grow colonizers. I would check renal function and adjust antibiotic doses, avoiding nephrotoxic agents when possible. Imaging is not required when the clinical diagnosis is classic, but ultrasound or magnetic resonance imaging can help if there is diagnostic uncertainty or suspected deep abscess. I would also assess the dialysis graft for infection or thrombosis, because a same-arm infection can threaten vascular access.

An indolent course with modest pain, slow progression, and failure to respond to standard antibiotics should raise suspicion for mycobacterial or fungal tenosynovitis. A history of a thorn prick, aquarium exposure, or soil contact suggests Mycobacterium marinum or Sporothrix. Nodular lymphangitis, chronic swelling, and minimal systemic toxicity are clues. I would obtain mycobacterial and fungal cultures, send tissue for histopathology, and consider acid-fast and fungal stains. If cultures are negative and symptoms persist, repeat debridement and biopsy may be needed. I would avoid repeated courses of empirical antibiotics without tissue diagnosis, because they can suppress cultures and delay appropriate treatment. For atypical infections, prolonged targeted antimicrobial therapy is usually required, and infectious disease consultation is appropriate.