The acutely ill patient with fever and rash often presents a diagnostic challenge for physicians. The distinctive appearance of an eruption in concert with a clinical syndrome may facilitate a prompt diagnosis and the institution of life-saving therapy or critical infection-control interventions. Representative images of many of the rashes discussed in this chapter are included in Chap. e7.
Approach to the Patient: Fever and Rash
A thorough history of patients with fever and rash includes the following relevant information: immune status, medications taken within the previous month, specific travel history, immunization status, exposure to domestic pets and other animals, history of animal (including arthropod) bites, existence of cardiac abnormalities, presence of prosthetic material, recent exposure to ill individuals, and exposure to sexually transmitted diseases. The history should also include the site of the onset of the rash and its direction and rate of spread.
A thorough physical examination entails close attention to the rash, with an assessment and precise definition of its salient features. First, it is critical to determine the type of lesions that make up the eruption. Macules are flat lesions defined by an area of changed color (i.e., a blanchable erythema). Papules are raised, solid lesions <5 mm in diameter; plaques are lesions >5 mm in diameter with a flat, plateaulike surface; and nodules are lesions >5 mm in diameter with a more rounded configuration. Wheals (urticaria, hives) are papules or plaques that are pale pink and may appear annular (ringlike) as they enlarge; classic (nonvasculitic) wheals are transient, lasting only 24 h in any defined area. Vesicles (<5 mm) and bullae (>5 mm) are circumscribed, elevated lesions containing fluid. Pustules are raised lesions containing purulent exudate; vesicular processes such as varicella or herpes simplex may evolve to pustules. Nonpalpable purpura is a flat lesion that is due to bleeding into the skin. If <3 mm in diameter, the purpuric lesions are termed petechiae; if >3 mm, they are termed ecchymoses. Palpable purpura is a raised lesion that is due to inflammation of the vessel wall (vasculitis) with subsequent hemorrhage. An ulcer is a defect in the skin extending at least into the upper layer of the dermis, and an eschar (tâche noire) is a necrotic lesion covered with a black crust.
Other pertinent features of rashes include their configuration (i.e., annular or target), the arrangement of their lesions, and their distribution (i.e., central or peripheral).
For further discussion, see Chaps. 51, 53, and 121.
This chapter reviews rashes that reflect systemic disease, but it does not include localized skin eruptions (i.e., cellulitis, impetigo) that may also be associated with fever (Chap. 125). This chapter does not intend to be all-inclusive, but it covers the most important and most common diseases associated with fever and rash. Rashes are classified herein on the basis of the morphology and distribution of lesions. For practical purposes, this classification system is based on the most typical disease presentations. However, morphology may vary as rashes evolve, and the presentation of diseases with rashes is subject to many variations (Chap. 53). For instance, the classic petechial rash of Rocky Mountain spotted fever (RMSF) (Chap. 174) may initially consist of blanchable erythematous macules distributed peripherally; at times, however, the rash associated with RMSF may not be predominantly acral or no rash may develop at all.
Diseases with fever and rash may be classified by type of eruption: centrally distributed maculopapular, peripheral, confluent desquamative erythematous, vesiculobullous, urticaria-like, nodular, purpuric, ulcerated, or eschar. Diseases are listed by these categories in Table 17-1, and many are highlighted in the text. However, for a more detailed discussion of each disease associated with a rash, the reader is referred to the chapter dealing with that specific disease. (Reference chapters are cited in the text and listed in Table 17-1.)
Table 17-1 Diseases Associated with Fever and Rash
| Save Table
Table 17-1 Diseases Associated with Fever and Rash
||Group Affected/Epidemiologic Factors
|Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DIHS/DRESS)
|Rubeola (measles, first disease)
||Discrete lesions that become confluent as rash spreads from hairline downward, sparing palms and soles; lasts ≥3 days; Koplik's spots
||Cough, conjunctivitis, coryza, severe prostration
|Rubella (German measles, third disease)
||Spreads from hairline downward, clearing as it spreads; Forschheimer spots
|Erythema infectiosum (fifth disease)
||Human parvovirus B19
||Brightred “slapped-cheeks” appearance followed by lacy reticular rash that waxes and wanes over 3 weeks; rarely, papular-purpuric “gloves-and-socks” syndrome on hands and feet
||Most common among children 3–12 years old; occurs in winter and spring
||Mild fever; arthritis in adults; rash following resolution of fever
|Exanthem subitum (roseola, sixth disease)
||Human herpesvirus 6
||Diffuse maculopapular eruption over trunk and neck; resolves within 2 days
||Usually affects children <3 years old
||Rash following resolution of fever; similar to Boston exanthem (echovirus 16); febrile seizures may occur
papules; less commonly, urticarial or vesicular oral or genital ulcers
||Individuals recently infected with HIV
Pharyngitis, adenopathy, arthralgias
||Diffuse maculopapular eruption (5% of cases; 90% if
ampicillin is given);
Log In to View More
If you don't have a subscription, please view our individual subscription options
below to find out how you can gain access to this content.
Want access to your institution's subscription?
Sign in to your MyAccess Account while you are actively authenticated on this website
via your institution (you will be able to tell by looking in the top right corner
of any page – if you see your institution’s name, you are authenticated). You will
then be able to access your institute’s content/subscription for 90 days from any
location, after which you must repeat this process for continued access.
If your institution subscribes to this resource, and you don't have a MyAccess account,
please contact your library's reference desk for information on how to gain access
to this resource from off-campus.
AccessMedicine Full Site: One-Year Subscription
Connect to the full suite of AccessMedicine content and resources including more than 250 examination and procedural videos, patient safety modules, an extensive drug database, Q&A, Case Files, and more.
Pay Per View: Timed Access to all of AccessMedicine
48 Hour Subscription
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.