Piel Flashcards
(5 cards)
A 6-year-old girl is brought to the physician by her father because of a 3-day history of sore throat, abdominal pain, nausea, vomiting, and high fever. She has been taking acetaminophen for the fever. Physical examination shows cervical lymphadenopathy, pharyngeal erythema, and a bright red tongue. Examination of the skin shows a generalized erythematous rash with a rough surface that spares the area around the mouth. Which of the following is the most likely underlying mechanism of this patient’s rash?
This patient has typical features of scarlet fever due to Streptococcus pyogenes (group A streptococcus, GAS), a gram-positive bacteria whose release of erythrogenic toxin A, B, or C, results in excessive release of inflammatory mediators. The rash in scarlet fever blanches with pressure and is most pronounced in flexural areas such as axillae, popliteal fossae, and the inguinal region. Other toxigenic effects of GAS infection include streptococcal toxic shock syndrome, erysipelas, and necrotizing fasciitis.
All cases of scarlet fever should be treated with antibiotics such as penicillin V or, in patients allergic to penicillin, macrolides.
A 6-year-old boy is brought to the physician for evaluation of bilateral erythematous skin lesions on the flexures of the elbows and knees. He has been scratching the areas frequently. He has had similar lesions intermittently for the last 2 years. A photograph of the lesions on the back of the knees is shown. This patient’s skin lesions are most likely associated with which of the following?
A reversible decrease in FEV1/FVC ratio with the administration of bronchodilators is a characteristic spirometry finding in asthma. Atopic dermatitis, as seen in this patient, is often associated with other atopic diseases such as asthma and allergic rhinitis (called the “atopic triad” if all three conditions are present).
A 5-year-old boy is brought to the physician because of a painful, burning rash on his left arm for 3 days. Three years ago, he was diagnosed with heart failure due to congenital heart disease and received an allogeneic heart transplantation. He takes cyclosporine to prevent chronic transplant rejection. He has not received any routine childhood vaccinations. A photograph of the rash is shown (shingles). Microscopic examination of a skin biopsy specimen is most likely to show which of the following findings?
Multinucleated giant cells and Cowdry A inclusions are characteristic histopathologic findings found on a Tzanck test of shingles lesions. Initial infection with varicella zoster virus (VZV) causes chickenpox, which this patient likely developed because he has not received any vaccinations. Immunosuppression (e.g., from cyclosporine taken to prevent chronic transplant rejection) is a risk factor for reactivation of VZV (shingles) after a period of latency in dorsal root ganglia. Other risk factors include older age, HIV infection, and malnutrition.
Multinucleated giant cells and Cowdry A inclusions are also found in skin lesions caused by herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2).
A previously healthy 3-month-old girl is brought to the physician because of fever, irritability, and rash for 3 days. The rash started around the mouth before spreading to the trunk and extremities. Her temperature is 38.6°C (101.5°F). Examination shows a diffuse erythematous rash with flaccid bullae on the neck, flexural creases, and buttocks. Gentle pressure across the trunk with a gloved finger creates a blister (Nikolsky’s sign). Oropharyngeal examination shows no abnormalities. Which of the following is the most likely underlying mechanism of these skin findings?
Cleavage of desmoglein-1 by exfoliative toxin is the mechanism underlying SSSS, a blistering skin disorder that results from toxemia following focal Staphylococcus aureus infections (usually of the nasopharynx). Desmoglein-1 is a desmosomal protein located in the granular layer of the epidermis and responsible for attaching the keratinocytes to one another. Loss of the cell-to-cell attachments results in intraepidermal fissure formation, which presents as fragile, flaccid blisters. Bullous impetigo is also caused by staphylococcal exfoliative toxins but remains localized, in contrast to SSSS.
Treatment of SSSS consists of IV antibiotics and supportive care. Although most patients respond well to conventional therapy, SSSS is a potentially fatal condition with an increased mortality rate in adults.
A previously healthy 22-year-old man comes to the physician because of multiple nodules on his hands that first appeared a few months ago. He works as a computer game programmer. His father died of a myocardial infarction at 37 years of age, and his mother has rheumatoid arthritis. A photograph of the lesions is shown. The nodules are firm, mobile, and nontender. Which of the following is the most likely mechanism underlying this patient’s skin findings?
Tendinous xanthomas form from plasma lipoproteins that have extravasated and accumulated in tendons (most commonly the extensor tendons of the hands and the Achilles tendon) in patients with extremely high levels of circulating lipids. These findings and the death of this patient’s father from a myocardial infarction at 37 years of age should raise suspicion for familial hypercholesterolemia, which increases the risk of developing premature coronary artery disease.
Large, perivascular infiltrates with foam cells and Touton giant cells can be seen on histopathological examination of tendinous xanthomas.
