COVID-19 associated cutaneous polyarteritis nodosa

A 30-year-old woman with a 31-week third pregnancy and mild gestational diabetes was admitted to hospital in February 2022 with two days of arthralgias in knees and ankles, diffuse leg tenderness and swelling, and painful erythematous subcutaneous nodular 1–2 cm lesions on buttocks, thighs and legs. Fig. 1a. She had no fever, respiratory symptoms, abdominal pain, synovitis nor neurological complaints. She was not on any medication, did not smoke nor use drugs and had been previously in good health. Her vital signs on admission were within normal limits. Positive laboratory findings included: increased C-reactive protein levels (59 mg/L normal value <10 mg/L); 16,100 white blood cells/mm3; 519,000 platelets/mm3 and proteinuria in 24 h 450 mg. HBV surface antigen and hepatitis C antibodies were nonreactive and human immunodeficiency virus test was negative. Antinuclear antibodies, anti-dsDNA, antineutrophil cytoplasmic antibodies, antiphospholipid antibodies and lupus anticoagulant tests were negative. Doppler ultrasound ruled out deep venous thrombosis. Routine PCR test for SARS-CoV-2 on admission was positive, without any other symptoms associated to COVID-19. Chest x-ray was normal. COVID-19 vaccine scheme was as follows: CoronaVac 2 doses in March 2021, plus booster with BNT162b2 in January 2022, forty days previous to the onset of symptoms. On day three of admission nodular lesions had diminished but prominent livedo reticularis was observed from the lower half of the abdomen to the ankles. Fig. 1b. A surgical skin biopsy obtained on 04 March 2022 from one of the lesions on the buttocks showed perivascular inflammatory infiltrate (Fig. 2a), neutrophilic inflammatory infiltrating medium-caliber vessels in the hypodermis, with fibrinoid necrosis and thrombus formation (Fig. 2b, 2c and 2d) compatible with PAN. Labor was induced at 35 weeks of pregnancy as mild proteinuria had developed. Her daughter was born healthy, weighing 2.3 Kg, and breastfeeding was allowed. After delivery prednisone 40 mg/day was started with diagnosis of cutaneous PAN. Azathioprine was initiated but stopped due to pancytopenia and alopecia. At the time of writing this report, more than one year after disease onset, she maintains treatment with prednisone 5 mg/day with almost complete skin lesions response, as mild livedo is still present