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Systemic dermatology

Inflammatory reactions key points test

Which of the following may result in lobular panniculitis? # Erythema nodosum # Recurrent herpes simplex infection #! α1 antitrypsin deficiency #! Pancreatitis Explanation: Lobular panniculitis may be idiopathic or due to α1-antitrypsin deficiency, pancreatitis, pancreatic carcinoma, tuberculosis and nodular vasculitis. Which of the following are features of erythema nodosum? # Target lesions on the extremities #! Septal panniculitis #! Fever and malaise #! Resolution in 6 – 12 weeks Explanation: Erythema nodosum is a septal panniculitis. It results in painful erythematous subcutaneous nodules, most often affecting the lower legs. It may result in mild fever, malaise and arthralgia. It generally resolves within two or three months. Which of the following is unlikely to be the cause of erythema nodosum? * Beta haemolytic streptococcal infection * Sarcoidosis *! Recurrent herpes simplex infection * Inflammatory bowel disease Explanation: Erythema nodosum can be due to sarcoidosis, beta haemolytic streptococcal infection, tuberculosis, many other infectious agents, inflammatory bowel disease, malignancies, Behçet's syndrome, Sweet's disease and drugs. Which of the following are features of erythema multiforme (EM)? #! Target lesions on the extremities # Septal panniculitis #! Fever and malaise # Resolution in 6 – 12 weeks Explanation: Erythema multiforme is an acute eruption of erythematous target lesions on the extremities. It may be associated with fever and malaise and resolves within one to three weeks. Which of the following is unlikely to be the cause of erythema multiforme? * Co-trimoxazole *! Sarcoidosis * Recurrent herpes simplex infection * Orf Explanation: Erythema multiforme minor is most often due to herpes simplex but it may also follow orf, mycoplasma, and immunization. Erythema multiforme major is usually due to a drug. In comparison to EM minor, EM major (Steven’s Johnson syndrome) has which of the following features? # Blisters and erosions on the fingers and toes #! Blisters and erosions on the genitalia #! Greater likelihood of drug aetiology # Greater likelihood of viral origin Explanation: EM major or Steven's Johnson syndrome is characterised by mucosal blisters and erosions but like EM minor, it is often associated with target lesions on the extremities. Toxic epidermal necrolysis * Is due to an overdose of cytotoxic medications * Results in exfoliative erythroderma * Is due to IgE-mediated Type I hypersensitivity reaction *! Should not be treated with high dose corticosteroids Explanation: Toxic epidermal necrolysis can be a type 2 or type 4 hypersensitivity reaction (cytotoxic mediators), and is most often provoked by sulphonamides, anti-inflammatories, anticonvulsants and allopurinol. High dose corticosteroids have been associated with increased mortality. Dermatoses with dense dermal infiltrates of neutrophils include: #! Pyoderma gangrenosum # Erythema nodosum #! Sweet’s disease # Erythema annulare centrifugum Explanation: Neutrophilic dermatoses include pyoderma gangrenosum and Sweet's disease. Erythema nodosum is a septal panniculitis (mixed infiltrate) and annular erythemas have lymphocytic infiltrates. Pyoderma gangrenosum and Sweet’s disease may be associated with: * Recurrent herpes simplex infections * Sarcoidosis * Co-trimoxazole use *! Haematological malignancies Explanation: Neutrophilic dermatoses are associated with inflammatory bowel disease, rheumatoid arthritis and haematological malignancies. They may also arise in otherwise healthy individuals in response to upper respiratory infection.