MKSAP Quiz: Evaluation for persistent fatigue, headache, myalgia, arthralgia
A 44-year-old woman is evaluated for persistent fatigue, headache, myalgia, and arthralgia. Early localized Lyme disease was diagnosed 2 months ago after the patient returned from a camping trip in western New Jersey with the symptoms described and a skin eruption of erythema migrans. Following a physical exam and lab studies, what is the most likely diagnosis?
A 44-year-old woman is evaluated for persistent fatigue, headache, myalgia, and arthralgia. Early localized Lyme disease was diagnosed 2 months ago after the patient returned from a camping trip in western New Jersey with the symptoms described and a skin eruption of erythema migrans. She was treated with a 14-day course of doxycycline with resolution of the cutaneous lesions but continuation of the other symptoms, which now are adversely affecting her work and personal life. Her only medication is ibuprofen.
On physical examination, vital signs are normal. The patient has full range of motion of the joints. No skin lesions, synovitis, or effusions are noted.
Results of laboratory studies, including a complete blood count, comprehensive metabolic panel, and lactate dehydrogenase measurement, are all within normal limits.
Which of the following is the most likely diagnosis?
A. Anaplasmosis
B. Babesiosis
C. Late-stage Lyme disease
D. Post–Lyme disease syndrome
E. Powassan virus infection
MKSAP Answer and Critique
The correct answer is D. Post–Lyme disease syndrome. This content is available to MKSAP 18 subscribers as Question 9 in the Infectious Disease section. More information about MKSAP is available online.
This patient most likely now has post–Lyme disease syndrome (PLDS). In a patient who lives in or has visited an area endemic for Lyme disease, a skin lesion consistent with erythema migrans is sufficient to make a clinical diagnosis of early localized Lyme disease. Early localized Lyme disease is treated with doxycycline for 10 to 21 days. Despite appropriate therapy, this patient continues to experience nonspecific but debilitating symptoms that have persisted for several months. She most likely has PLDS, a poorly understood sequela of Lyme disease that sometimes is misclassified as “chronic Lyme disease” despite a lack of microbiologic evidence of a persistent viable organism. PLDS is thought to be due to a disordered immunologic response to the preceding infection. Most patients slowly improve over a period of 6 months, and treatment is directed toward symptom amelioration. Randomized controlled trials have shown that patients with PLDS do not respond to prolonged courses of antibiotic therapy, and such treatment is not warranted in this population.
Anaplasma phagocytophilum, Babesia microti, and Powassan virus are all transmitted by the same tick vector as Borrelia burgdorferi, the causative spirochete of Lyme disease, and coinfections may occur. Anaplasmosis is treated with doxycycline, and the patient's previous course of treatment should have eradicated any incubating disease.
In contrast, doxycycline is not effective therapy for babesiosis. Mild babesiosis may present as a nonspecific flu-like illness, although fever typically is present. The hallmark of babesiosis is hemolytic anemia, and normal laboratory studies in this patient essentially exclude this diagnosis.
In the United States, late-stage Lyme disease most commonly presents as an inflammatory arthritis involving larger joints. The patient has no physical findings consistent with this diagnosis and had appropriate treatment to prevent progression to late-stage Lyme disease.
Powassan virus causes meningoencephalitis rather than the nonspecific symptoms manifested by this patient.
Key Point
- Post–Lyme disease syndrome is a poorly understood sequela of Lyme disease thought to be due to a disordered immunologic response to the preceding infection; most patients slowly improve over a 6-month course, and treatment is directed toward symptom amelioration.