stuvia.com Dermatology . stuvia.com Fungal Infections – Tinea corporis is a superficial fungal infection most typically seen in hot, humid climates. Any species of dermatophyte may cause this condition, but Trichophyton rubrum is the most frequent culprit. The lesions are pruritic, erythematous, scaly, and have a red ring with central clearing . Exposure to infected animals, people, and public places are major risk factors. Tinea corporis is most common in preadolescents. It is diagnosed clinically or with a skin scraping and potassium hydroxide examination. Topical antifungals are the preferred therapy. Tinea versicolor is a superficial fungal infection of the skin. It is characterized by pale, velvety pink or whitish, hypopigmented macules that do not tan and do not appear scaly, but scale on scraping. The causative agent is Ma/assezia furfur. Patients often present in the office once they notice that the involved areas never tan . Sometimes, the condition presents as hyper - pigmented macules that are velvety -tan or brownish. Microscopic examination of skin scrapings after KOH preparation reveals large, blunt hyphae and thick -walled budding spores (classic "spagheṄ and meatballs" appearance). Topical treatment with selenium sulfide lotion and ketoconazole shampoo is recommended, and patients are informed that the change in pigmentation requires months to return to normal. Pityriasis rosea lesions appear as oval, fawn -colored plaques that measure up to 2 cm in diameter and occur in a Christmas tree paGern. The initial lesion is called the herald patch , and is followed by a generalized eruption in 1 -2 weeks Scarlet fever is also a toxin -related process. caused by a toxin -producing strain of group A Beta -hemolytic streptococcus. It is primarily a disease of children. Usually there is a preceding group A strep tococcal infection of another site (e.g. tonsillitis, pharyngitis). Skin findings are stuvia.com typically preceded by a prodrome of fever, headache, vomiting, and sore throat. Twelve to 48 hours later, fine pink blanching papules appear on the neck and upper trunk and quickly generalize with flexural accentuation. The eruption is said to have a rough, sandpaper -like texture. Measles is a highly contagious disease that is caused by Param yxovirus. The chronology of the disease is as follows: • Exposure to the virus (transmitted via respiratory droplets) • Prodrome after 10 days (coryza, conjunctivitis, cough - remember the 3 'C's!) • Koplik's spots appear approximately 48 hours before the skin rash (red spots with bluish specks over the buccal mucosa, opposite the premolar tooth) and slowly fade once the rash appears • Characteristic rash is erythematous maculopapular, initially over the face, and then spreads to cover the entire trunk and extremities. The complications are pneumonia, vitamin A deficiency, and bronchiectasis. Late complications are immunosuppression and subacute sclerosing panencephalitis. Rubella is caused by the RNA togavirus. The chronology of the disease is as follows: • Exposure to the virus (transmitted via respiratory droplets) • Development of fever, malaise, and tender suboccipital adenitis after 14-21 days • Characteristic rash appears 1-5 days later (maculopapular rash initially on the face, and then spreading to involve the trunk and extremities, lasting for less than 3 days) Polyarthralgia is common in adults. Posterior cervical and posterior auricular lymphadenopathies are common. Few patients develop encephalopathy. FetaI infection leads to congenital rubella syndrome. The risk to the fetus is highest if the mother contracts rubella in the first trimester . Patients can be treated with acetaminophen for symptomatic relief. Patients can be infectious from 1 week prior to the onset of the rash to 15 days after. Live attenuated rubella vaccine offers the best protection against infection. Rosacea is characterized by a rosy hue with telangiectasia over the cheeks, nose, and chin. Flushing of these areas is typically precipitated by hot drinks, heat, emotion, and other causes of rapid body temperature changes. The episodes are usually intermittent, but can progressively lead to permanently flushed skin. Sometimes, papules and pustules may be present (as in this patient). Rosacea most commonly occurs in 30 - to 60 -year-old patients with
