Atypical Exanthems Warrant Reassurance

While most exanthems are self-limiting, some are not, making it important to establish a specific diagnosis, according to Dr. Anthony J. Mancini.

"Parents want to go read up on these things, and they want to know how long it's going to take to go away," Dr. Mancini said in an interview. "If you can characterize it … it's helpful for parents to know. At least they may have some answers. They know that it's going to take a while to resolve, and that saves you from follow-up phone calls and visits to the office when they're frantic because it's still there 4 weeks later."

Clinicians have learned to keep an eye out for the truly bad actors, like oral mucosa necrosis that could signal Stevens-Johnson syndrome, or the centripetal spread of exanthem with petechiae from a tick bite that could signal Rocky Mountain spotted fever.

At the women's and pediatric dermatology seminar sponsored by Skin Disease Education Foundation (SDEF), Dr. Mancini—head of pediatric dermatology at Children's Memorial Hospital in Chicago—reviewed common exanthems, and many that aren't so common. But he paid special attention to three of the newer or atypical exanthems: Arcanobacterium haemolyticum, unilateral laterothoracic exanthem, and acute generalized exanthematous pustulosis (AGEP).

A. haemolyticum

Often masquerading as scarlet fever, A. haemolyticum typically appears in adolescents and young adults as a sore throat with a scarlet fever–like rash. It is important for physicians to recognize and diagnose A. haemolyticum because it can be treated, noted Dr. Mancini.

The first clue that it is not scarlet fever or mononucleosis is a negative throat culture for strep and a negative Monospot. Most labs can test for A. haemolyticum, but only if they know to look, because they need to plate it on a different agar.

Although A. haemolyticum will probably resolve on its own with time, children can be treated effectively with a macrolide antibiotic such as an erythromycin, azithromycin, or clarithromycin. Patients do not respond well to penicillin antibiotics, an important distinction from streptococcal infection, he said.

Unilateral Laterothoracic Exanthem

Most physicians "have probably seen unilateral laterothoracic exanthem, but they may have misdiagnosed it as contact dermatitis," Dr. Mancini said. Beginning on one side of the body, usually at the arm, armpit, or trunk, the exanthem may initially look like a contact dermatitis but then begins to spread. Even after spreading, the exanthem maintains predominance on the initial side of involvement.

The cause is unknown, but it is probably viral, he said. It requires no treatment and typically takes 6–8 weeks to resolve.

Acute Generalized Exanthematous Pustulosis

AGEP is often mistaken for drug-induced pustular psoriasis, and the literature is filled with a wide range of reported drug associations, including amoxicillin, erythromycin, NSAIDs, and even pseudoephedrine, but current thinking is that it is often viral, at least in children.

"It's an important entity to recognize, because AGEP can have a sudden onset, with fevers and numerous widespread nonfollicular pustules, which can look a lot like pustular psoriasis," he said. It's self-limited, but children do tend to appear more toxic with AGEP than with some other exanthems, especially if they are young. They may have low-grade fevers, and their white counts may be mildly elevated. Treatment is supportive, with antihistamines, cool compresses, and topical steroids if patients are uncomfortable. AGEP will resolve over 2 weeks or so with desquamation Dr. Mancini disclosed being a consultant to SkinMedica and Galderma, and on the speakers bureau of Promius and Galderma. SDEF and this news organization are owned by Elsevier.

Acute generalized exanthematous pustulosis onset can be sudden.

Source Courtesy Dr. Anthony J. Mancini

While most exanthems are self-limiting, some are not, making it important to establish a specific diagnosis, according to Dr. Anthony J. Mancini.

"Parents want to go read up on these things, and they want to know how long it's going to take to go away," Dr. Mancini said in an interview. "If you can characterize it … it's helpful for parents to know. At least they may have some answers. They know that it's going to take a while to resolve, and that saves you from follow-up phone calls and visits to the office when they're frantic because it's still there 4 weeks later."

Clinicians have learned to keep an eye out for the truly bad actors, like oral mucosa necrosis that could signal Stevens-Johnson syndrome, or the centripetal spread of exanthem with petechiae from a tick bite that could signal Rocky Mountain spotted fever.

At the women's and pediatric dermatology seminar sponsored by Skin Disease Education Foundation (SDEF), Dr. Mancini—head of pediatric dermatology at Children's Memorial Hospital in Chicago—reviewed common exanthems, and many that aren't so common. But he paid special attention to three of the newer or atypical exanthems: Arcanobacterium haemolyticum, unilateral laterothoracic exanthem, and acute generalized exanthematous pustulosis (AGEP).

A. haemolyticum

Often masquerading as scarlet fever, A. haemolyticum typically appears in adolescents and young adults as a sore throat with a scarlet fever–like rash. It is important for physicians to recognize and diagnose A. haemolyticum because it can be treated, noted Dr. Mancini.

The first clue that it is not scarlet fever or mononucleosis is a negative throat culture for strep and a negative Monospot. Most labs can test for A. haemolyticum, but only if they know to look, because they need to plate it on a different agar.

Although A. haemolyticum will probably resolve on its own with time, children can be treated effectively with a macrolide antibiotic such as an erythromycin, azithromycin, or clarithromycin. Patients do not respond well to penicillin antibiotics, an important distinction from streptococcal infection, he said.

Unilateral Laterothoracic Exanthem

Most physicians "have probably seen unilateral laterothoracic exanthem, but they may have misdiagnosed it as contact dermatitis," Dr. Mancini said. Beginning on one side of the body, usually at the arm, armpit, or trunk, the exanthem may initially look like a contact dermatitis but then begins to spread. Even after spreading, the exanthem maintains predominance on the initial side of involvement.

The cause is unknown, but it is probably viral, he said. It requires no treatment and typically takes 6–8 weeks to resolve.

Acute Generalized Exanthematous Pustulosis

AGEP is often mistaken for drug-induced pustular psoriasis, and the literature is filled with a wide range of reported drug associations, including amoxicillin, erythromycin, NSAIDs, and even pseudoephedrine, but current thinking is that it is often viral, at least in children.

"It's an important entity to recognize, because AGEP can have a sudden onset, with fevers and numerous widespread nonfollicular pustules, which can look a lot like pustular psoriasis," he said. It's self-limited, but children do tend to appear more toxic with AGEP than with some other exanthems, especially if they are young. They may have low-grade fevers, and their white counts may be mildly elevated. Treatment is supportive, with antihistamines, cool compresses, and topical steroids if patients are uncomfortable. AGEP will resolve over 2 weeks or so with desquamation Dr. Mancini disclosed being a consultant to SkinMedica and Galderma, and on the speakers bureau of Promius and Galderma. SDEF and this news organization are owned by Elsevier.

Acute generalized exanthematous pustulosis onset can be sudden.

Source Courtesy Dr. Anthony J. Mancini

While most exanthems are self-limiting, some are not, making it important to establish a specific diagnosis, according to Dr. Anthony J. Mancini.

"Parents want to go read up on these things, and they want to know how long it's going to take to go away," Dr. Mancini said in an interview. "If you can characterize it … it's helpful for parents to know. At least they may have some answers. They know that it's going to take a while to resolve, and that saves you from follow-up phone calls and visits to the office when they're frantic because it's still there 4 weeks later."

Clinicians have learned to keep an eye out for the truly bad actors, like oral mucosa necrosis that could signal Stevens-Johnson syndrome, or the centripetal spread of exanthem with petechiae from a tick bite that could signal Rocky Mountain spotted fever.

At the women's and pediatric dermatology seminar sponsored by Skin Disease Education Foundation (SDEF), Dr. Mancini—head of pediatric dermatology at Children's Memorial Hospital in Chicago—reviewed common exanthems, and many that aren't so common. But he paid special attention to three of the newer or atypical exanthems: Arcanobacterium haemolyticum, unilateral laterothoracic exanthem, and acute generalized exanthematous pustulosis (AGEP).

A. haemolyticum

Often masquerading as scarlet fever, A. haemolyticum typically appears in adolescents and young adults as a sore throat with a scarlet fever–like rash. It is important for physicians to recognize and diagnose A. haemolyticum because it can be treated, noted Dr. Mancini.

The first clue that it is not scarlet fever or mononucleosis is a negative throat culture for strep and a negative Monospot. Most labs can test for A. haemolyticum, but only if they know to look, because they need to plate it on a different agar.

Although A. haemolyticum will probably resolve on its own with time, children can be treated effectively with a macrolide antibiotic such as an erythromycin, azithromycin, or clarithromycin. Patients do not respond well to penicillin antibiotics, an important distinction from streptococcal infection, he said.

Unilateral Laterothoracic Exanthem

Most physicians "have probably seen unilateral laterothoracic exanthem, but they may have misdiagnosed it as contact dermatitis," Dr. Mancini said. Beginning on one side of the body, usually at the arm, armpit, or trunk, the exanthem may initially look like a contact dermatitis but then begins to spread. Even after spreading, the exanthem maintains predominance on the initial side of involvement.

The cause is unknown, but it is probably viral, he said. It requires no treatment and typically takes 6–8 weeks to resolve.

Acute Generalized Exanthematous Pustulosis

AGEP is often mistaken for drug-induced pustular psoriasis, and the literature is filled with a wide range of reported drug associations, including amoxicillin, erythromycin, NSAIDs, and even pseudoephedrine, but current thinking is that it is often viral, at least in children.

"It's an important entity to recognize, because AGEP can have a sudden onset, with fevers and numerous widespread nonfollicular pustules, which can look a lot like pustular psoriasis," he said. It's self-limited, but children do tend to appear more toxic with AGEP than with some other exanthems, especially if they are young. They may have low-grade fevers, and their white counts may be mildly elevated. Treatment is supportive, with antihistamines, cool compresses, and topical steroids if patients are uncomfortable. AGEP will resolve over 2 weeks or so with desquamation Dr. Mancini disclosed being a consultant to SkinMedica and Galderma, and on the speakers bureau of Promius and Galderma. SDEF and this news organization are owned by Elsevier.

Acute generalized exanthematous pustulosis onset can be sudden.

Source Courtesy Dr. Anthony J. Mancini