n early 2020, dermatologists in Europe noticed a sharp increase in chilblains, an inflammatory dermatosis that generally affects the dorsal feet or hands during periods of damp and cold, but not freezing, conditions, associated with the COVID-19 pandemic. [1][2][3][4][5][6][7][8] Few patients with chilblains tested positive for SARS-CoV-2 or its antibodies, although access to testing was limited. [1][2][3][4] Subsequent reports of series with complete viral and antibody testing indicated low frequencies of tests with positive results. [5][6][7][8] The underlying causes of an increase in chilblains related to the pandemic are controversial. 5,[7][8][9][10] Published cases of presumed secondary chilblains in the setting of confirmed COVID-19 infection indicate that COVID-19associated symptoms preceded chilblains by up to 30 days. 2,11 On noticing an increase in chilblains after the shelter-athome order was initiated in 6 Bay Area counties in California on March 16, 2020 (and statewide on March 18, 2020), we conducted a retrospective cohort study to test the hypothesis that increased cases of chilblains appeared in the same locations as increased cases of COVID-19 over time. Methods Setting and DesignKaiser Permanente Northern California provides comprehensive, integrated care to 4.4 million people, with all clinical information entered into an electronic medical record. The health care system operates 23 medical centers that are located to serve defined urban, suburban, and exurban population centers. Northern California is known for its microclimates. The IMPORTANCE Beginning in March 2020, case reports and case series linked the COVID-19 pandemic with an increased occurrence of chilblains, but this association has not been evaluated in an epidemiologic study.OBJECTIVE To assess whether a correlation exists between COVID-19 incidence and chilblains incidence. DESIGN, SETTING, AND PARTICIPANTSA retrospective cohort study was conducted within the Kaiser Permanente Northern California system from January 1, 2016, to December 31, 2020; health plan members of all ages were included.EXPOSURE COVID-19 incidence in 207 location-months, representing 23 geographic locations in northern California across 9 months. MAIN OUTCOME AND MEASURESChilblains incidence was the main outcome. The association of chilblains incidence with COVID-19 incidence across the 207 location-months was measured using the Spearman rank correlation coefficient. RESULTSOf 780 patients with chilblains reported during the pandemic, 464 were female (59.5%); mean (SD) age was 36.8 (21.8) years. COVID-19 incidence was correlated with chilblains incidence at 207 location-months (Spearman coefficient 0.18; P = .01). However, only 17 of 456 (3.7%) patients with chilblains tested during the pandemic were positive for SARS-CoV-2, and only 9 of 456 (2.0%) were positive for SARS-CoV-2 within 6 weeks of the chilblains diagnosis. Test results of 1 of 97 (1.0%) patients were positive for SARS-CoV-2 IgG antibodies. Latinx patients were disproportionately affected by C...

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We describe a case of sporotrichoid lymphangitis (nodular lymphangitis or lymphocutaneous syndrome) that was an unusual clinical presentation of Staphylococcus aureus infection in a diabetic patient. Common pyogenic bacteria should be considered in the differential diagnosis of sporotrichoid lymphangitis.

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