My Synopsis of "Evaluating the Febrile Patient with a Rash"

Evaluating the Febrile Patient with a Rash
HARRY D. MCKINNON, JR., MAJ, MC, USA, and THOMAS HOWARD, COL, MC, USA, Dewitt Army Community Hospital, Fort Belvoir, Virginia
Am Fam Physician. 2000 Aug 15;62(4):804-816.
http://www.aafp.org/afp/2000/0815/p804.html


     When trying to diagnosis a rash, a proper description of the lesion is important. Macules are round and flat. Papules are less than 0.5 cm and raised. Nodules are deep in the dermis and palpable. Plaques are large elevations of the skin. A pustule is a purulent fluid filled area of skin. A vesicle is a small pustule.
    Eruptions can be categorized into central, peripheral, and petechial. Centrally distributed eruptions are more common. They usually start in the head and neck, and then progress peripherally. Examples include rubeola, rubella, roseola, and erythema infectiosum. Rubeola is also known as measles. The rash starts at the hairline and spreads downward. It does not affect the palms and soles. It also causes blue spots on the oral mucosa, called koplik spots. Rubella looks the same as rubeola except that it only lasts 2-3 days (as opposed to 4-6 days in measles). It is also less severe. An infection of HHV-6 is also known as roseola, or exanthem subitum. It occurs after fever but spares the face. It fades within 3 days. Parvovirus causes fifth's disease, also known as slapped cheek disease or erythema infectiosum. The red facial rash occurs after the fever resolves. It then spreads to produce a lacy reticular rash the lasts up to 8 weeks. Parvovirus can cause fetal hydrops and fetal death in pregnant women.
     Lyme disease presents with a very common target shaped lesion called erythema migrans. It has a characteristic central clearing. There may also be central necrosis, induration, or vesiculation. Patients in this situation may present with a recent history of hiking, camping, or being in a tick infested area. It is more common on the extremities. Penicillin or cephalosporin treatment may cause a drug reaction that will look like a viral exanthem.
     Peripheral eruptions present as erythema multiforme, which is a maculopapular rash more common in men. It is often found on the palms, soles, knees and elbows. It initially looks like a dull-red macular lesion that grows into a papule with a central vesicle or bullae. The mouth and lips are often involved. There are two classifications of erythema multiforme. In the minor form, the bullae and systemic symptoms are absent, and the mucous membranes are not involved. The major form is usually due to a drug reaction. It presents with bullae, mucosal involvement, fever, difficult micturition, and conjunctivitis. Secondary syphilis presents with a localized diffuse rash on the head, neck, palms, and soles. It usually occurs 6 months after infection. Patients may also present with condyloma lata.
     Petechial eruptions can be a sign of a serious infection, such a meningococcemia. It occurs more commonly in infants, alcoholics, asplenic patients, and those with complement deficiencies. Along with a polymorphous, maculopapular, petechial rash, the patient will have spiking fevers, tachypnea, tachycardia, and mild hypertension. Chronic meningococcemia will have arthritis and arthralgia.
     Rocky mountain spotted fever is another cause of a rash in a febrile patient. It usually presents on the fourth day of infection as pink macules on the wrists, forearms, ankles, palms, and soles. It will spread to include the arms, legs, abdomen and face. The rash eventually becomes red and petechial. Scarlet fever has a "finely punctate erythema" on the trunk and face, which then spreads to the extremities. Patients will also present with a strawberry tongue.
     Toxic shock syndrome and scalded skin syndrome will present with as a diffuse scarlatiniform rash. Nikolsky's sign will be positive. Kawasaki's disease presents with a rash that is scarlatiniform on the trunk and erythematous on the palm and soles. The lips may look dry and cracked. The oropharynx will be injected. There may also be a strawberry tongue. Herpes zoster is a painful pustular lesion that will affect a unilateral dermatome. Chicken pox looks like "a dewdrop on a rosepetal" which starts on the head and spreads down and to the extremities. The pustules will present in all stages of healing.
     Nodular eruptions present as erythema nodosum. It affects the legs, knees and arms.There are many causes which include infection, medication, SLE, sarcoidosis, ulcerative colitis, behcet's syndrome, and pregnancy.