{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T11:18:19Z","timestamp":1783682299878,"version":"3.55.0"},"reference-count":18,"publisher":"BMJ","issue":"7","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,6,24]]},"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:p>Multisystem inflammatory syndrome in adults (MIS-A) is a severe postinfectious complication of COVID-19. Renal involvement is common; however, histopathological findings have not been adequately characterised. We here report a case of a previously healthy man in his 60s who developed persistent fever, diarrhoea, glossitis and digital swelling approximately 3 weeks after COVID-19 infection. Antibiotic therapy was ineffective and renal function deteriorated. He was diagnosed with MIS-A and corticosteroid therapy produced marked clinical improvement. He was discharged 3 weeks after hospital admission. Renal biopsy demonstrated medullary haemorrhagic interstitial nephritis with preserved cortex, an uncommon pathological finding in renal injury secondary to COVID-19, which is consistent with possible immune-mediated endothelial injury.<\/jats:p>\n                  <jats:p>This case highlights medullary haemorrhagic interstitial nephritis as a potential pathological manifestation of MIS-A and illustrates a diagnostic pitfall. Recognition of MIS-A is essential for timely corticosteroid treatment and prevention of life-threatening multiorgan failure.<\/jats:p>","DOI":"10.1136\/bcr-2026-273927","type":"journal-article","created":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T11:10:20Z","timestamp":1783681820000},"page":"e273927","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Medullary haemorrhagic interstitial nephritis in multisystem inflammatory syndrome in adults following COVID-19"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-7338-0050","authenticated-orcid":false,"given":"Hiroki","family":"Matsuoka","sequence":"first","affiliation":[{"name":"Nephrology, Daido Hospital, Nagoya, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2975-2874","authenticated-orcid":false,"given":"Hideaki","family":"Shimizu","sequence":"additional","affiliation":[{"name":"Nephrology, Daido Hospital, Nagoya, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroshi","family":"Kitamura","sequence":"additional","affiliation":[{"name":"Chiba Higashi Byoin, Chiba, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7907-0009","authenticated-orcid":false,"given":"Joel","family":"Branch","sequence":"additional","affiliation":[{"name":"Yao Tokushukai Sogo Byoin, Yao, 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