Arzhang Cyrus Javan, Andrea Censullo A 35-year-old male from Massachusetts with no significant past medical history presents to your urgent care clinic in July with complaints of mild fatigue and a slowly expanding rash near his axilla that appeared 6 days ago. Review of systems is otherwise negative. He embarked on a hike in the woods near his home 3 weeks prior to his visit but denies any animal or insect bites. He is single and has had no recent sexual activity. He denies drug use. Vital signs are normal. There are no pertinent positives on physical exam besides his rash (see Fig. 51.1). Erythema migrans (EM), the rash caused by Lyme disease, is high on the differential. EM begins at the site of a tick bite and is frequently homogenously red during the first few days. Sometimes the centers of early lesions become intensely erythematous and indurated, vesicular, or necrotic. The red outer borders slowly expand over the course of several days to create a large annular lesion, while the center of the rash may partially clear, hence the terms “target” or “bull’s-eye” that are often used to describe this rash. Occasionally, the expanding lesion remains an evenly intense red, several red rings can be found within the larger outside ring, or the central area turns blue before the lesion clears. The lesion is warm and is often described by patients as burning. It can sometimes be pruritic or even painful. EM can be accompanied by mild constitutional symptoms such as fatigue and malaise. Other etiologies to consider in the differential diagnosis for EM are cellulitis, hypersensitivity (allergic reaction) to tick bite saliva, a skin manifestation of a spider bite, tinea (ringworm) infections, and erythema multiforme. Cellulitis typically expands more rapidly, lacks central clearing, and is usually painful. Hypersensitivity (allergic reaction) to tick bite saliva also typically expands very rapidly and lacks central clearing. Spider bites can cause a lesion with a necrotic center and are often quite painful. Tinea (ringworm) lesions are, like EM, annular with central clearing, but they characteristically have peripheral scales. Multiple EM lesions (this can be observed in later stages of Lyme disease and will be described shortly) can resemble erythema multiforme. The distinguishing feature of erythema multiforme is that it can blister and cause lesions on the palms, soles, and mucous membranes. No further tests are warranted as the patient’s history and physical exam highly suggest a diagnosis of early Lyme disease (i.e., stage 1 or localized infection). This is the only stage of Lyme disease in which the diagnosis should be made on the basis of the clinical picture alone. Testing serologies (i.e., antibodies) isn’t warranted in this stage because significant circulating antibody levels may not have had time to develop. All other stages of Lyme disease require laboratory confirmation. Lyme disease is the most common tick-borne illness in North America and Europe. Lyme disease is caused by the spirochete bacteria Borrelia burgdorferi and can be transmitted to humans by various tick species with unique geographic distributions. The Ixodes scapularis tick (deer tick) is the primary vector in the United States and is found throughout New England, the Mid-Atlantic states, and also in Wisconsin, Michigan, and Minnesota. The majority of Lyme disease cases in the United States occur in these regions. Ixodes pacificus is another tick species that can infrequently transmit Lyme disease in the coastal regions of Oregon and northern California. No. Even though a tick must be attached for at least 24 hours to transmit Lyme disease, the tick in its nymphal stage, which is the period in its life cycle in which it infects humans, is quite small and often goes unnoticed. Therefore, the absence of a reported tick bite should not deter the clinician when considering Lyme disease as a diagnosis. Lyme is classified into three clinical stages, but there can be some overlap between them. Refer to Table 51.1 for a detailed description of these stages: • Early Infection: Stage 1 (Localized Infection): Occurs after an incubation period of 3 to 32 days. • Early Infection: Stage 2 (Disseminated Infection): Begins within days to weeks after the onset of EM. Some of the neurologic manifestations within this stage begin within weeks to months after the onset of EM. • Late Infection: Stage 3 (Persistent Infection): Occurs months after initial symptoms. TABLE 51.1 Clinical Manifestations of Lyme Disease With Recommended Therapy Stage 1 (Localized) General: mild flulike symptoms Skin: EM Stage 2 (Disseminated) General: malaise, fatigue, fever, headache Skin: multiple EM Rheumatologic: migratory arthralgias/myalgias Neurologic: cranial nerve palsy (especially facial nerve palsy) Cardiac:
A 35-Year-Old Male With Fatigue and Rash
What is your differential diagnosis?
What further testing needs to be performed to help establish a diagnosis?
What is the etiology of Lyme disease?
Is it unusual that the patient does not recall a tick bite?
What are the clinical stages of Lyme disease?
Stage
Clinical Manifestations
Preferred Route of Therapy
Oral (14-21 days)
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51 A 35-Year-Old Male With Fatigue and Rash
Case 51
