Dermatology Flashcards
A 28-year-old male diagnosed with psoriasis consults you at the clinic for follow-up. He is asking why he usually develops psoriatic lesions on areas of his skin exposed to trauma. What is this event called? (H20 C53 P333) A. Auspitz phenomenon B. Darier sign C. Koebner phenomenon D. Nikolsky sign
The answer is C. Psoriasis is one of the most common dermatologic diseases, affecting up to 2% of the world’s population. It is an immune-mediated disease clinically characterized by erythematous, sharply demarcated papules and rounded plaques covered by silvery micaceous scale. The skin lesions of psoriasis are variably pruritic. Traumatized areas often develop lesions of psoriasis (the Koebner or isomorphic phenomenon). In addition, other external factors may exacerbate psoriasis, including infections, stress, and medications (lithium, beta blockers, and antimalarial drugs).
A 36/F epilepsy patient was referred to the Gen Med senior for co-management of rash. Few days after starting phenytoin for status epilepticus, the patient was noted to develop widespread dusky macules, which eventually spread over more than half of the patient’s body. Later, the patient developed bullae over affected area accompanied by skin tenderness, which eventually sloughed off. Oral and ocular involvement was also noted. Which of the following is the most appropriate diagnosis for this patient? (H20 C54 P347) A. Erythema multiforme B. SJS-TEN overlap C. Stevens-Johnson syndrome (SJS) D. Toxic epidermal necrolysis (TEN)
The answer is D.
Toxic epidermal necrolysis is characterized by bullae that arise on widespread areas of tender erythema and then slough. This results in large areas of denuded skin. The associated morbidity, such as sepsis, and mortality rates are relatively high and are a function of the extent of epidermal necrosis. In addition, these patients may also have involvement of the mucous membranes and respiratory and intestinal tracts. Drugs are the primary cause of TEN, and the most common offenders are aromatic anticonvulsants (phenytoin, barbiturates, carbamazepine), sulfonamides, aminopenicillins, allopurinol, and NSAIDs. Severe acute graft-versus-host disease (grade 4), vancomycin-induced LABD, and flares of lupus can also resemble TEN.
Induction of SJS is most often due to drugs, especially sulfonamides, phenytoin, barbiturates, lamotrigine, aminopenicillins, nonnucleoside reverse transcriptase inhibitors (e.g., nevirapine), and carbamazepine. Widespread dusky macules and significant mucosal involvement are characteristic of SJS, and the cutaneous lesions may or may not develop epidermal detachment. If the latter occurs, by definition, it is limited to <10% of the body surface area (BSA). Greater involvement leads to the diagnosis of SJS/TEN overlap (10–30% BSA) or TEN (>30% BSA).
Which of the following portends a poorer prognosis for patients with SJS/TEN? (H20 C56 P368) A. Ethnicity B. Gastrointestinal involvement C. Specific causative drug D. Younger age
The answer is B. Patients with SJS/TEN initially present with fever >39°C (102.2°F); sore throat; conjunctivitis; and acute onset of painful dusky, atypical, target-like lesions. Intestinal and upper respiratory tract involvement are associated with a poor prognosis, as are older age and greater extent of epidermal detachment. At least 10% of those with SJS and 30% of those with TEN die from the disease. Drugs that most commonly cause SJS/TEN are sulfonamides, allopurinol, antiepileptics (e.g., lamotrigine, phenytoin, carbamazepine), oxicam NSAIDs, β-lactam and other antibiotics, and nevirapine. Frozen-section skin biopsy may aid in rapid diagnosis. At this time, there is no consensus on the most effective treatment for SJS/TEN. The best outcomes stem from early diagnosis, immediate discontinuation of the suspected drug, and meticulous supportive therapy in an intensive care or burn unit. Issues such as fluid management, atraumatic wound care, infection prevention and treatment, and ophthalmologic and respiratory support are critical. Systemic glucocorticoid therapy (prednisone 1–2 mg/kg) may be useful early in disease evolution; however, long-term or late systemic glucocorticoid use has been associated with increased mortality. After initial enthusiasm for the use of intravenous immunoglobulin (IVIG) in the treatment of SJS/TEN, more recent data question whether it is beneficial. There are emerging data to support treatment with cyclosporine and etanercept. Randomized studies to evaluate potential therapies are lacking and difficult to perform.
Which of the following is characteristic of lepromatous leprosy? (H20 C174 P1260-2)
A. Epitheliod macrophage differentiation
B. Langerhans giant cells
C. Lung and central nervous system involvement
D. Negative lepromin skin test
The answer is D.
