A woman in her sixties with a knee injury after a fall.

BACKGROUND

The diagnosis of necrotising soft tissue infections (NSTIs, necrotising fasciitis, myositis and cellulitis) may be clinically challenging, and can result in fatal outcomes.

CASE PRESENTATION: A previously healthy woman in her sixties fell and cut her right patella. The wound was complicated by localised infection, which subsequently developed into a bacterial bursitis. She responded to intravenous antibiotics and was followed up at the outpatient clinic. Nineteen days later she was admitted with the same symptoms and clinical presentation as at the previous admission. She was started on the same antibiotics based on the last prepatellar bursal fluid culture. This time, however, she became systemically impaired and septic. Many differential diagnoses were suspected, and she was repeatedly examined with the aid of blood samples, blood cultures, knee joint and prepatellar bursal punctures, and ultrasound scans. The patient's right lower extremity became swollen and was further examined with a CT scan, giving rise to suspicion of an NSTI. Ultimately four surgical revisions were performed (fasciotomy) in addition to continuous administration of antibiotics, fluid and pressor treatment. Biopsies of the fascia, muscle and fatty tissue were secured for microscopy, culture and histology. Unfortunately the patient died and histology confirmed necrotising fasciitis.

INTERPRETATION: NSTIs are aggressive infections with dismal outcomes. This case illustrates the importance of clinical suspicion of this diagnosis, also in healthy patients. Immediate treatment with surgical debridement and intravenous antibiotics is crucial.