Diagnostic Testing

The patient was asked to record daily body temperatures for three weeks (Figure 2 ). Complete blood count, comprehensive metabolic panel, liver function tests, thyroid stimulating hormone, erythrocyte sedimentation rate, C-reactive protein, chest X-ray, urinalysis, COVID-19 test, and influenza A and B tests were performed. Additionally, titers for Lyme disease, Anaplasmosis, Hepatitis C, and HIV were obtained. All were normal or negative, with the following exceptions: lymphocyte count was low at 780 per mL, monocyte count was elevated at 1302 per mL, inflammatory markers were increased, and 2+ ketones and trace protein were found on urinalysis. Elevation of inflammatory markers was perceived to be a non-specific finding. Abnormal lab results are listed in Table 1 , while normal lab results are listed inSupplemental Table 1 .

At the time of development of palmar rash, antinuclear antibody titer (ANA) was ordered. Three sets of blood cultures (obtained on different days) and transthoracic echocardiogram were also performed to exclude infectious endocarditis. The ANA titer was positive, but all other studies were normal. As the rash spread, fluorescent treponemal antibody absorption test (FTA-ABS) and rapid plasma reagin (RPR) test were ordered, both returning positive. Accordingly, secondary syphilis was diagnosed.