Diffuse or Reticulated Erythema

Key Term

Mucocutaneous lymph node syndrome

Erythema is defined as cutaneous diseases that present with large patches of red skin, without overlying changes in the epidermis. Included in this group are disorders that have a netlike or reticulated pattern of redness. Notably absent in this pattern are blisters, targetoid lesions, scale, or erythema that is photodistributed. As one would expect, as the lesions age, they may become scaly or peel. A classic example of this is a first-degree sunburn in which there is erythema confined to the site of sun exposure, with no primary epidermal changes that can be seen grossly. However, as the erythema resolves, the skin becomes scaly or even peels in sheets. Photodistributed erythema is discussed in Chapter 19 .

Differential Diagnosis of Erythema


  • Erythema infectiosum

  • Kawasaki disease

  • Rosacea

  • Scarlet fever

  • Toxic shock syndrome

Photodistributed (see Chapter 19 )

  • Dermatomyositis

  • Lupus erythematosus

  • Phototoxic drug eruptions

  • Sunburn

Reticulated Erythemas

  • Erythema infectiosum

  • Erythema ab igne

Important History Questions

How long has your redness been present?

Most causes of erythema are of recent duration because many, but not all of them, are due to a bacterial or viral toxin or a medication.

Have you started any new medications in the last 10 days?

This is a critical question because some erythemas may be drug-induced. The classic example would be doxycycline, which produces a photodistributed erythema.

Have you had any fever?

This question is directed toward determining a potential infectious cause, such as a viral or bacterial infection.

Do you have any other medical problems?

This question can elicit much important clinical information, including a history of a connective tissue disorder or history of rosacea.

Important Physical Findings

What is the distribution of the lesions?

Although not discussed in this chapter, some erythemas are photodistributed, including dermatomyositis, lupus erythematosus, phototoxic drug eruptions, and sunburn. Other erythemas, such as chemotherapy-induced acral erythema, demonstrate a predominantly acral distribution, and erythema secondary to rosacea is usually confined to the face.

Are lesions present in the oral mucosa?

Erythema associated with mucosal lesions are more likely to be due to infections, lupus erythematosus, or drug eruptions.

Are vesicles or blisters present?

Although a so-called pure erythema should not demonstrate blisters, some severe erythemas may at some time in their development develop vesicles or blisters. For example, a severe sunburn (second-degree sunburn) may develop blistering, which may be very focal, and although most cytoxic chemotherapy reactions present as erythema, severe reactions can develop focal blister formation.

Presence or absence of lesions with a reticulated (netlike) appearance

Although most variants of erythema do not demonstrate a reticulated appearance, some erythemas, including erythema infectiosum and erythema ab igne, frequently demonstrate a reticulated appearance.

Scarlet Fever

ICD10 code A38



Scarlet fever (scarlatina) is a toxic reaction to toxins (erythrogenic toxins A, B, and C) produced by group A β-hemolytic streptococci (Streptococcus pyogenes). Once patients acquire antibodies against these toxins, scarlet fever does not develop. This accounts for why most patients affected are children between the ages of 1 to 10 years, because they are less likely to have these antibodies. In the antibiotic era, scarlet fever has become much less common than it was formerly.

Clinical Features

  • Scarlet fever typically affects infants and children between the ages of 1 and 10 years.

  • Most patients have streptococcal pharyngitis, with symptoms that include sore throat, headache, fever (102–105° F [39–40.5°C]), malaise, or tonsillitis and, less commonly, streptococcal wound or pelvic infections.

  • Erythema typically begins 12 to 48 hours after the development of the primary infection.

  • Erythema most commonly begins on the neck, chest, and axillae, with rapid spread to the remainder of the body ( Fig. 4.1 ).

    Fig. 4.1

    Scarlet fever. Shown here is marked diffuse erythema of the neck, upper chest, and arms. Note early desquamation of the neck.

    (From the Fitzsimons Army Medical Center Collection, Aurora, CO.)

  • On the face, there is marked erythema, with a slapped cheek appearance and circumoral pallor.

  • Punctate erythematous papules rapidly develop on areas with erythema, typically described as sunburn with goose bumps ( Fig. 4.2 ).

    Fig. 4.2

    Punctate papules on a background of erythema, a pattern known as sunburn with goose bumps.

    (From the Fitzsimons Army Medical Center Collection, Aurora, CO.)

  • Linear petechial streaks may be seen in the flexures (e.g., axillae, antecubital, inguinal).

  • Patients may demonstrate a positive Rumpel-Leede tourniquet test result.

  • The tongue is initially white with prominent papillae, but as the illness progresses, the entire tongue becomes red, with prominent papillae classically described as a red strawberry tongue ( Fig. 4.3 ).

    Fig. 4.3

    Strawberry tongue in a patient with scarlet fever.

    (From the Fitzsimons Army Medical Center Collection, Aurora, CO.)

  • Rarely, clusters of small vesicles may appear on the trunk and/or extremities.

  • Desquamation that is most prominent on the hands and feet typically begins 7 to 10 days later.


  • The clinical presentation of a child with pharyngitis or tonsillitis and systemic symptoms, which include fever and rapidly spreading erythema, should initially suggest the diagnosis. As the disease progresses, numerous physical findings further support the diagnosis.

  • The complete blood count (CBC) reveals a leukocytosis with a left shift (~85%–95% polymorphonuclear leukocytes).

  • A throat culture should be done.

  • The antistreptolysin O (ASO) titer or streptozyme level is typically elevated.


  • Oral penicillin VK or oral erythromycin for 10 days is the treatment of choice.

Clinical Course

  • In the preantibiotic era, this disease often resulted in a fatal outcome (≈3%–20%). Complications of scarlet fever include acute glomerulonephritis and rheumatic fever (2%–3% of patients). With recognition and antibiotic treatment, the mortality rate is less than 1%. It is important to note that patients may continue to desquamate for as long as 6 weeks.

Toxic Shock Syndrome

ICD10 code A48.3



Toxic shock syndrome (TSS) is a rare complication of infection by strains of Staphylococcus aureus that produce TSS toxin-1 (TSST-1). Less commonly a similar disorder, sometimes referred to as toxic shock–like syndrome (TSLS), is produced by a streptococcal pyrogenic exotoxin produced by strains of Streptococcus pyogenes . In the 1980s, there was an epidemic associated with superabsorbent tampons. Since the withdrawal of these products, the number of reported cases has decreased. The source of the infection can still be a tampon; however, it also can be produced by infections of other mucosal and cutaneous sites.

Clinical Features

  • See diagnostic criteria below.


Sep 15, 2018 | Posted by in Dermatology | Comments Off on Diffuse or Reticulated Erythema
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