Drug-induced cutaneous vasculitis and anticoagulant-related cutaneous adverse reactions: insights in pathogenesis, clinical presentation, and treatment

Leukocytoclastic Vasculitis of the Foot and Ankle: A Case Report With Over Five-Year Follow-Up

The estimated incidence of leukocytoclastic vasculitis of any etiology is between 15 and 30 people per million per year. Despite being a rare pathologic entity, leukocytoclastic vasculitis has many documented etiologies. Here, we report on a case of a 47-year-old man with liver cirrhosis who was admitted to our institution for diffuse palpable purpura of the distal lower extremities. Workup was largely negative for infectious and systemic causes. The patient received multiple days of intravenous antibiotics and consultations with infectious disease, dermatology, and podiatry. Skin biopsies confirmed a diagnosis of idiopathic leukocytoclastic vasculitis. A steroid taper was prescribed, and the patient had clinical resolution and healing of skin lesions. After 5.5 years after the vasculitic episode, the patient remained free of cutaneous lower extremity lesions. Medication-induced leukocytoclastic vasculitis and associations with systemic illness or malignancy were ruled out. In the lower extremities, misdiagnosis of cellulitis for noninfectious dermatologic conditions is common. Clinicians must have a wide differential and take a multidisciplinary approach to similar types of cases to reduce unnecessary antibiotic usage.

A case of delayed maculopapular eruption to ibuprofen and acute urticaria to acetaminophen

We present the unique case of a 33-year-old male referred to our clinic in search of analgesic options who was found to have a delayed hypersensitivity reaction to ibuprofen manifesting as a maculopapular rash and acute urticaria to acetaminophen. Non-steroidal anti-inflammatory drugs are associated with predictable reactions as well as immunoglobulin E-mediated reactions or T-cell mediated reactions. This case highlights the importance of knowledge of the different types of reactions to non-steroidal anti-inflammatory agents as well as the risk of cross reactivity. Delayed reaction to a single non-steroidal agent is rare; urticaria to acetaminophen is very rare. This is the first report we have found in the literature where one individual has a delayed reaction manifesting as rash to ibuprofen as well as urticaria to acetaminophen. We challenged our patient to aspirin which helped identify that his delayed reaction was only to ibuprofen and urticaria only to acetaminophen. The case also highlights the importance of an oral provocation challenge when no contraindications exist which helped us find that he could take celecoxib and avoid narcotics as initial therapy.

Extensive skin necrosis in an elderly woman on dabigatran

Dabigatran, a novel oral anticoagulant, is a direct thrombin inhibitor and is being increasingly used owing to the advantage of dosing without the need for laboratory monitoring. While extensive skin necrosis is known to be associated with oral anticoagulants such as warfarin and factor Xa inhibitors, dabigatran toxicity typically manifests with bleeding, especially in the elderly. We describe a 70-year-old woman who was prescribed dabigatran for the treatment of unprovoked deep venous thrombosis. She developed bleeding diathesis along with extensive skin necrosis and acute kidney injury shortly after commencing the drug. Haemodialysis was given in view of dabigatran toxicity and complications of kidney dysfunction which resolved promptly over a week. However, the patient succumbed to severe sepsis from secondary skin infections. It is crucial to closely monitor for signs of dabigatran toxicity, especially in the elderly patients.

Cutaneous adverse effects of the available COVID-19 vaccines

Vaccination has played a crucial role in the improvement of global health. Some of the world's deadliest diseases, like smallpox and rinderpest, have been eradicated with the help of vaccines, and many others have been restrained. The appearance of the strain of coronavirus disease 2019 (COVID-19) severe acute respiratory syndrome coronavirus 2 and its impact on global health have made the development of effective and safe vaccines crucial for this new lethal disease. So far, there are three main types of COVID-19 vaccines in use around the world: messenger RNA-based vaccines, adenoviral vector vaccines, and inactivated whole-virus vaccines. Some of them have passed through phase 3 of safety and efficacy trials and are widely used for prophylaxis of COVID-19 infection. A plethora of cutaneous adverse events have been reported, most of them mild or moderate injection-site reactions. Some rare delayed inflammatory reactions such as "COVID arm" have also been reported, posing questions on their pathophysiology and clinical importance. Some rare serious adverse events, such as vaccine-induced prothrombotic immune thrombocytopenia and anaphylaxis, have been described raising great concerns on the safety of some widely spread vaccines. More data need to be collected with further and more detailed analysis. The overall risk of such severe adverse reactions remains extremely low, and the benefits of the existing vaccines in combating the widespread threat of COVID-19 continue to outweigh the risk of their side effects.

The Emerging Role of the Innate Immune Response in Idiosyncratic Drug Reactions

Idiosyncratic drug reactions (IDRs) range from relatively common, mild reactions to rarer, potentially life-threatening adverse effects that pose significant risks to both human health and successful drug discovery. Most frequently, IDRs target the liver, skin, and blood or bone marrow. Clinical data indicate that most IDRs are mediated by an adaptive immune response against drug-modified proteins, formed when chemically reactive species of a drug bind to self-proteins, making them appear foreign to the immune system. Although much emphasis has been placed on characterizing the clinical presentation of IDRs and noting implicated drugs, limited research has focused on the mechanisms preceding the manifestations of these severe responses. Therefore, we propose that to address the knowledge gap between drug administration and onset of a severe IDR, more research is required to understand IDR-initiating mechanisms; namely, the role of the innate immune response. In this review, we outline the immune processes involved from neoantigen formation to the result of the formation of the immunologic synapse and suggest that this framework be applied to IDR research. Using four drugs associated with severe IDRs as examples (amoxicillin, amodiaquine, clozapine, and nevirapine), we also summarize clinical and animal model data that are supportive of an early innate immune response. Finally, we discuss how understanding the early steps in innate immune activation in the development of an adaptive IDR will be fundamental in risk assessment during drug development. SIGNIFICANCE STATEMENT: Although there is some understanding that certain adaptive immune mechanisms are involved in the development of idiosyncratic drug reactions, the early phase of these immune responses remains largely uncharacterized. The presented framework refocuses the investigation of IDR pathogenesis from severe clinical manifestations to the initiating innate immune mechanisms that, in contrast, may be quite mild or clinically silent. A comprehensive understanding of these early influences on IDR onset is crucial for accurate risk prediction, IDR prevention, and therapeutic intervention.