A 14-year-old boy with severe erythema multiforme due to amoxicillin

The most common cause of erythema multiforme (EM) in children is infectious diseases which account for approximately 90% of cases. Drug eruptions are another common cause. Here we are reporting about a male patient aged 14 years with lymphadenitis who developed severe diffuse erythema during the course of treatment with medications including several antibiotics and nonsteroidal anti-inflammatory drugs (NSAIDs). Based on the pathological findings of the skin biopsy, the skin rash was due to EM. Upon investigating the underlying cause of EM, viral antibody was positive for Coxsackie A6, lymphocyte transformation testing (LTT) was positive for one of the NSAIDs, and the patch test (PT) was positive for amoxicillin. Based on the pattern of distribution of the skin rash, the cause of EM was considered to be drug-induced eruption due to amoxicillin. In this case, we did not derive a diagnosis of drug eruption without investigating the possibility of drug induction, because most cases of EM in children are induced by infection and the antibody against Coxsackie A6 was elevated. To diagnose the possibility of amoxicillin-induced EM, it was important to distinguish between the distribution patterns of infectious versus drug-induced EM and to evaluate the possibility of drug induction by both LTT and PT. If the diagnosis of amoxicillin-induced EM, had not been made, the potential recurrence of EM with amoxicillin could have occurred.

Metal allergy in primary and revision total knee arthroplasty : a scoping review and evidence-based practical approach

Aims

Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA).

Methods

Studies were identified by searching electronic databases: Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Embase, from their inception to November 2020, for studies evaluating TKA patients with metal hypersensitivity/allergy. All studies reporting on diagnosing or managing metal hypersensitivity in TKA were included. Data were extracted and summarized based on study design, study population, interventions and outcomes. A practical guide is then formulated based on the available evidence.

Results

We included 38 heterogeneous studies (two randomized controlled trials, six comparative studies, 19 case series, and 11 case reports). The evidence indicates that metal hypersensitivity is a rare complication with some histopathological features leading to pain and dissatisfaction with no reliable screening tests preoperatively. Hypoallergenic implants are viable alternatives for patients with self-reported/confirmed metal hypersensitivity if declared preoperatively; however, concerns remain over their long-term outcomes with ceramic implants outperforming titanium nitride-coated implants and informed consent is paramount. For patients presenting with painful TKA, metal hypersensitivity is a diagnosis of exclusion where patch skin testing, lymphocyte transformation test, and synovial biopsies are useful adjuncts before revision surgery is undertaken to hypoallergenic implants with shared decision-making and informed consent.

Conclusion

Using the limited available evidence in the literature, we provide a practical approach to metal hypersensitivity in TKA patients. Future national/registry-based studies are needed to identify the scale of metal hypersensitivity, agreed diagnostic criteria, and management strategies.

Cite this article: Bone Jt Open 2021;2(10):785–795.

Toxic epidermal necrolysis: Part II. Prognosis, sequelae, diagnosis, differential diagnosis, prevention, and treatment

Toxic epidermal necrolysis (TEN) is a life-threatening, typically drug-induced, mucocutaneous disease. TEN has a high mortality rate, making early diagnosis and treatment of paramount importance. New but experimental diagnostic tools that measure serum granulysin and high-mobility group protein B1 (HMGB1) offer the potential to differentiate early TEN from other, less serious drug reactions, but these tests have not been validated and are not readily available. The mainstay of treatment for TEN involves discontinuation of the offending drug, specialized care in an intensive care unit or burn center, and supportive therapy. Pharmacogenetic studies have clearly established a link between human leukocyte antigen allotype and TEN. Human leukocyte antigen testing should be performed on patients of East Asian descent before the initiation of carbamezapine and on all patients before the initiation of abacavir. The effectiveness of systemic steroids, intravenous immunoglobulins, plasmapheresis, cyclosporine, biologics, and other agents is uncertain.