The herald patch is usually followed by smaller spots and itching. Pityriasis rosea commonly goes away on its own in 10 weeks or less and is treated with nonprescription medications and remedies to relieve itching. If you notice a circular rash on yourself or a child, a visit to the doctor for an accurate diagnosis is often warranted.
Your doctor might refer you to a dermatologist. Many skin conditions have similar appearances and symptoms, so the original diagnosis may have been inaccurate. Ringworm, also called dermatophytosis or tinea, is a fungal infection of the skin.
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They're tried and true. Notoriously, these infections are caused by dermatophytes, a collective term that describes three genera — Microsporum , Trichophyton , and Epidermophyton. Tinea infections are caused by close contact with infected persons, animals, or, occasionally, soil, and are spread to multiple body areas via autoinoculation when an infected region is scratched. Tinea can be diagnosed confidently when characteristic lesions described below are observed.
When available, the diagnosis can be confirmed by observing branching hyphae under the microscope using a potassium hydroxide KOH preparation. Tinea corporis and tinea cruris, the most common subtypes of dermatophytosis, are discussed briefly in this report.
Tinea corporis is a superficial dermatophyte infection of the body, not involving the scalp, face, hands, feet, or groin. Lesions are similar to those of tinea corporis, characterized by an asymmetric, well-defined, mildly erythematous patch with associated scale. The advancing border is raised and may contain vesicles, pustules, or papules. For localized tinea corporis or cruris, pedis, and faciei, topical antifungals, such as imidazoles clotrimazole, miconazole, ketoconazole, econazole, oxiconazole, sulconazole or allylamines naftifine, terbinafine , should be used once to twice daily for two to six weeks, including two weeks following clearance.
Granuloma annulare GA is a relatively common, self-limiting disorder of the dermis that affects women twice as often as men. Granuloma annulare can be diagnosed clinically by its unique distribution and morphology.
Asymptomatic lesions with smooth, non-scaly contours are differentiated easily from the pruritic, scaly, and rough lesions of tinea. Biopsy with histopathologic correlation can be used to confirm or establish the diagnosis when not clinically obvious.
Reassurance and observation is appropriate, as GA is benign and self-limiting. If left alone, one half of cases will resolve within two years.
Pityriasis rosea is a common eruption primarily seen in adolescents and young adults. Lesions are mildly pruritic and oriented along cleavage lines. A small subset of patients will experience a prodrome of headache, fever, and generalized malaise days to weeks prior to the initial outbreak.
When the rash is localized to the trunk, axillae, or groin, it commonly is mistaken for tinea. Tinea rarely is as widespread, and its lesions generally exude more significant central clearing. The classic presentation often is alarming to patients, prompting medical evaluation.
However, treatment generally is not required, as the eruption spontaneously remits in three to eight weeks. Erythema annulare centrifugum EAC belongs to a group of disorders characterized by raised, erythematous lesions that form annular, polycyclic, or arcuate arrangements. See Figure 2. Lesions have a predilection for the trunk and proximal extremities, sparing the hands, feet, face, and mucosa.
Diagnosis relies on clinical presentation. Centrally, lesions lack the associated crusts or vesicles commonly seen with tinea. Annular psoriasis may present similarly, but these lesions have diffuse, thick scaling throughout as opposed to the fine, trailing scale around the margin in EAC.
EAC often has a waxing and waning course that persists for about nine months. While rare, a basic cancer workup is warranted to rule out a paraneoplastic cause.
If pruritus is present or treatment is desired, corticosteroids often are effective, but topical applications are preferred, as recurrence upon discontinuation of systemic agents is common. Erythema chronicum migrans ECM is the cutaneous manifestation of Lyme disease. In the United States, Borrelia spirochetes are transmitted to humans by an infected Ixodes tick. For most patients, ECM at the site of the tick bite is the first sign of infection. As with most tick bites, an erythematous, small, round papule will appear at the site of the bite, and within days, the surrounding erythema will migrate peripherally, forming a large, erythematous plaque.
Primary lesions can reach 15 cm in diameter and commonly are found on the trunk, axilla, groin, and popliteal fossa. Generally, these secondary lesions will not have the targetoid appearance of the primary lesion and will spare the palms and soles. While the skin manifestations are mostly asymptomatic, accompanying symptoms of Lyme disease are common. Early in the disease course, a mild flu-like illness consisting of general malaise, fever, headache, nausea, vomiting, arthralgias, myalgias, and photophobia can occur.
Early recognition and accurate diagnosis can prevent progression of disease and subsequent lifelong rheumatologic, neurologic, and cardiac complications. In a case of suspected Lyme disease, cutaneous findings are the most sensitive sign of early infection. A detailed travel history, recent bites, or outdoor exposures should raise clinical suspicion. Lab findings may include an elevated erythrocyte sedimentation rate, elevated liver function tests, and mild anemia.
Adults should be treated with a day course of doxycycline. Rarely, patients experience a chronic course lasting longer than six weeks or progress to anaphylaxis.
Chronic urticaria almost always occurs in adults and often does not have an obvious trigger. Shape varies, but lesions often are round and blanch centrally, conferring an annular appearance. The hallmark finding in urticaria is its transient course. As a general rule, individual wheals do not last longer than 24 hours.
Urticaria can be classified as allergic, physical, or idiopathic. Allergic urticaria can be IgE-mediated, occurring in response to foods milk, eggs, wheat, shellfish, nuts , inhalants pollen, dander , medications penicillin , or complement-mediated in the case of serum sickness.
Physical urticarias include dermatographic urticaria, occurring where skin has been stroked; cholinergic urticaria, occurring in response to fever and hot baths; cold urticaria, occurring on distal extremities upon rewarming; pressure urticaria, often occurring on the feet and buttocks hours after pressure has been applied; solar urticaria, occurring after exposure to light; and exercise-induced urticaria, which presents with large lesions five to 30 minutes into exercise.
Urticaria is a clinical diagnosis based on history and physical exam. Laboratory tests rarely are indicated and generally are not recommended. Difficulty arises when patients present asymptomatically after an eruption, limiting the exam. As mentioned earlier, individual lesions should not last longer than 24 hours, although an attack may last much longer.
If a physical cause is suspected, provocative testing can uncover the offending stimuli. Treatment for acute urticaria involves avoidance of identifiable triggers and use of first- or second-generation antihistamines. Lichen planus LP is an idiopathic, inflammatory disease of the skin and mucus membranes that primarily affects middle-aged adults.
Oral lesions typically are painful, especially when ulcerated. Lesions are characterized by asymptomatic, small, annular papules or plaques with raised borders, typically purple to white in color. Centrally, lesions may be hyperpigmented or skin-colored.
Tinea is classically more erythematous and scaly than LP, while lesions of GA are less numerous and have smooth borders. Cutaneous LP often is self-limiting; most cases resolve spontaneously within one year.
Cutaneous larva migrans is a serpiginous eruption caused by animal hookworm larvae as they migrate through the epidermis. See the contact page for location and hours. Would you like to switch to the accessible version of this site?
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Accessibility View Close toolbar. Dermatophyte tinea infections. Superficial fungal infection. Ringworm risk and prevention. Centers for Disease Control and Prevention. Kelly AP, et al. Fungal and yeast infections. McGraw-Hill Education; Accessed July 14, Mukwende M, et al. George's University of London; Related Ringworm on a shoulder Ringworm on an arm. Mayo Clinic Press Check out these best-sellers and special offers on books and newsletters from Mayo Clinic.
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