Detailed summary of alternate diagnoses among MIS-C- patients
| Diagnosis | Number |
| Bacterial infection | 24 |
| Anaplasmosis | 1 |
| Bacterial lymphadenitis | 7 |
| Dental abscess | 1 |
| Labial abscess | 1 |
| Lyme disease | 2* |
| Mycobacterium flavescens mediastinal lymphadenitis | 1 |
| Non-typhoidal Salmonella enteritis | 2 |
| Pneumonia (presumed bacterial) | 1 |
| Retropharyngeal abscess | 1 |
| Ruptured AOM/parotid abscess/infected branchial cleft cyst | 1 |
| Urinary tract infection | 4 |
| Small bowel intussusception/necrosis and peritonitis | 1 |
| Staphylococcal toxic shock syndrome | 1 |
| Acute viral infection | 10 |
| Acute CMV | 1 |
| Acute EBV | 3* |
| Adenovirus URI | 2 |
| Coxsackievirus-associate herpangina | 1 |
| Human metapneumovirus URI | 2 |
| Rhinovirus URI | 1 |
| Autoimmune/autoinflammatory disease | 12 |
| Autoimmune cholangiopathy | 1 |
| Coeliac disease | 1 |
| Inflammatory bowel disease | 1 |
| Kawasaki disease | 4 |
| Kikuchi disease (complicated by MAS/HLH) | 1 |
| Systemic JIA (complicated by MAS/HLH) | 1 |
| PFAPA | 2 |
| Urticaria multiforme | 1 |
| Oncology | 1 |
| Langerhans cell histiocytosis | 1 |
| Toxic exposures | 2 |
| EVALI | 2 |
| No diagnosis | 20 |
| Total patients | 68* |
*One patient was diagnosed with both Lyme and EBV infection.
AOM, acute otitis media; CMV, cytomegalovirus; EBV, Epstein-Barr virus; EVALI, e-cigarette or vaping product use-associated lung injury; HLH, hemophagocytic lymphohistiocytosis; JIA, juvenile idiopathic arthritis; MAS, macrophage activation syndrome; MIS-C, multisystem inflammatory syndrome in children; PFAPA, periodic fever, aphthous stomatitis, pharyngitis, adenitis; URI, upper respiratory infection.