not-yet-known not-yet-known not-yet-known unknown DISCUSSION This case is a reminder that the constellation of symptoms present in Lyme disease can easily be ascribed to different causes (such as in our patient case ascribing the rash to a spider bite or cellulitis, and the fever and malaise a URI). This presentation is notable for both the atypical appearance of the rash in the popliteal fossa, which mimicked cellulitis, as well as for the rapid progression of neurologic symptoms including headache and Bell’s palsy. The rash of Lyme disease, if it occurs at all, can vary significantly6. Although the bullseye rash of EM is most common, it only develops typical central clearing after several days. In a study of 118 confirmed Lyme cases with a rash, only 9% of patients had central clearing in rash appearance.7 In our case, the appearance of the rash at day 2 of illness was not consistent with EM, but instead presented with induration and generalized erythema, mimicking cellulitis. Specific details that indicate a variant of EM such as the necrotic center were only apparent during the first ED visit, and at that point were subtle enough to potentially be missed and did not fully develop until the second ED presentation. Subtle hints that a cellulitic rash may be a variant of EM include any level of central clearing, and the presence of a central nodule or a necrotic center.6 Wariness on anchoring is particularly important during the COVID-19 pandemic11 for patients who present with common associated symptoms, such as fever and myalgias, as in our case.5 Other symptoms that overlap between Lyme disease and COVID-19/ URIs are malaise, headache and arthralgias.12 The presence of a rash (even if not the classic presentation of EM), a fever that persists for longer than 5 days, and lack of respiratory symptoms should all prompt the clinician to investigate possible Lyme disease. Even in areas that are not endemic for Lyme, cases due to travel remain possible. If labs are obtained, possible findings include an elevated erythrocyte sedimentation rate, transaminitis, thrombocytopenia, and non-specific abnormalities.8 Serology can be useful in cases with uncertain diagnosis, but it also contains several pitfalls. For example, IgM antibodies appear 1 to 2 weeks after infection, leaving the possibility of the test being falsely negative in beforehand. Furthermore, in a minority of patients (such as ours), the ELISA for IgM will be positive but the western blot is negative.13 This means that clinicians need to maintain a high index of suspicion for Lyme disease even with contradicting or delayed serology findings. Ultimately, diagnosing Lyme disease identification often relies on clinical symptoms alone. Treatment of Lyme disease consists of antibiotic therapy with 100mg of doxycycline twice daily for 10 days (preferred), 500mg of amoxicillin three times a day for 14 days, or 500mg of cefuroxime twice daily for 14 days.9 Treatment should be initiated when enough clinical suspicion exists, without waiting for test results as this increases the chance of progression to late Lyme and its associated neurologic and cardiac complications. Because of the difficulty in cases like these to distinguish between cellulitis and EM, if there’s enough suspicion for Lyme disease then an antibiotic that also covers Lyme should be used (such as doxycycline or cefuroxime) rather than a first-generation cephalosporin, the mainstay for current treatment guidelines on uncomplicated cellulitis in the USA.10 Although sometimes categorized as a “late” manifestation, the neurologic aspects of disseminated Lyme can sometimes be seen almost concurrently with the early aspect of the disease.3 In our case, Bell’s palsy and severe headache began at day 8 post presumed infection, namely a Bell’s palsy and severe headache. The presence of meningeal signs and/or intractable headache should raise concerns for Lyme meningitis, which would necessitate inpatient management but would not change the choice of antibiotic.8 Other late manifestations include arthralgias, carditis, and persistent neurologic deficits.3 There is currently no consensus on treating the Bell’s Palsy of Lyme disease with steroids, and the Infectious Diseases Society of America (IDSA) does not recommend for or against their use. However, they do recommend the extension of treatment from 10 days of doxycycline to 14-21 days.9