{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T22:54:23Z","timestamp":1788216863222,"version":"build-2803163510"},"reference-count":24,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:00:00Z","timestamp":1774915200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Pediatric Reports"],"abstract":"<jats:p>Background\/Objectives: This aim of this study was to describe the demographic, clinical, and laboratory characteristics of hospitalized children with benign acute childhood myositis (BACM) and to evaluate seasonal patterns, including changes observed during the COVID-19 pandemic. Methods: We conducted a retrospective single-center review of pediatric patients hospitalized with a diagnosis of BACM between January 2016 and December 2024. Clinical, laboratory, and epidemiological data were analyzed, including seasonal distribution before and after the COVID-19 pandemic. Results: We identified 47 cases of BACM, with a male predominance (66%) and a median age of 7 years. Most cases (72%) occurred during autumn and spring. The most common prodromal symptoms were fever, cough and rhinorrhea. Bilateral calf pain was the most frequent presenting symptom. The median creatine phosphokinase (CPK) level was 4986 U\/L, with higher values in boys (p = 0.040). Higher CPK levels were associated with longer hospital stays in our cohort (p = 0.030). Influenza B was the most frequently identified pathogen (63%). No BACM cases were recorded during the COVID-19 pandemic period (2020\u20132022), followed by an increase in 2024. All patients fully recovered, with a median hospital stay of 3.2 days. Conclusions: BACM is a self-limiting condition with a characteristic clinical and laboratory profile. The absence of cases during the COVID-19 pandemic suggests a possible association between reduced viral circulation and BACM incidence. Awareness of its typical presentation may support early diagnosis, reduce unnecessary investigations, and facilitate appropriate clinical management.<\/jats:p>","DOI":"10.3390\/pediatric18020047","type":"journal-article","created":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T09:26:12Z","timestamp":1775121972000},"page":"47","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Benign Acute Childhood Myositis Before and After COVID-19: A Nine-Year Retrospective Study"],"prefix":"10.3390","volume":"18","author":[{"given":"Helena","family":"Ferreira","sequence":"first","affiliation":[{"name":"Pediatric Department, Hospital Pedro Hispano, ULS Matosinhos, 4464-513 Matosinhos, Portugal"},{"name":"Pediatric Department, Centro Materno-Infantil do Norte, ULS Santo Ant\u00f3nio, 4050-651 Porto, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-8514-2867","authenticated-orcid":false,"given":"Carolina","family":"Pinto da Costa","sequence":"additional","affiliation":[{"name":"Pediatric Department, Hospital Pedro Hispano, ULS Matosinhos, 4464-513 Matosinhos, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-4995-6886","authenticated-orcid":false,"given":"Sofia Silva","family":"Faria","sequence":"additional","affiliation":[{"name":"Pediatric Department, Hospital Pedro Hispano, ULS Matosinhos, 4464-513 Matosinhos, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ana","family":"Lu\u00edsa Correia","sequence":"additional","affiliation":[{"name":"Pediatric Department, Hospital Pedro Hispano, ULS Matosinhos, 4464-513 Matosinhos, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sofia","family":"Aroso","sequence":"additional","affiliation":[{"name":"Pediatric Department, Hospital Pedro Hispano, ULS Matosinhos, 4464-513 Matosinhos, Portugal"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4341","DOI":"10.1007\/s00431-023-05115-9","article-title":"Benign acute children myositis: 5 years experience in a tertiary care pediatric hospital","volume":"182","author":"Attaianese","year":"2023","journal-title":"Eur. J. Pediatr."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4641","DOI":"10.1007\/s00431-024-05786-y","article-title":"Benign acute childhood myositis: A scoping review of clinical presentation and viral etiology","volume":"183","author":"Majava","year":"2024","journal-title":"Eur. J. Pediatr."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1111\/j.1651-2227.1957.tb08627.x","article-title":"Myalgia cruris epidemica","volume":"46","author":"Lundberg","year":"1957","journal-title":"Acta Paediatr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1055\/a-1792-7606","article-title":"Benign Acute Childhood Myositis: Our Experience on Clinical Evaluation","volume":"53","author":"Gangi","year":"2022","journal-title":"Neuropediatrics"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2127","DOI":"10.1212\/WNL.53.9.2127","article-title":"Benign acute childhood myositis: Laboratory and clinical features","volume":"53","author":"Mackay","year":"1999","journal-title":"Neurology"},{"key":"ref_6","first-page":"268","article-title":"Benign acute childhood myositis: Clinical series and literature review","volume":"88","author":"Cavagnaro","year":"2017","journal-title":"Rev. Chil. Pediatr\u00eda"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"e15273","DOI":"10.1111\/ped.15273","article-title":"Benign acute childhood myositis: Factors associated with muscle symptoms and resolution","volume":"64","author":"Bodur","year":"2022","journal-title":"Pediatr. Int."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1007\/s00431-020-03835-w","article-title":"Influenza-associated myositis: A single-centre, 5-year retrospective study","volume":"180","author":"Kerr","year":"2021","journal-title":"Eur. J. Pediatr."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"443","DOI":"10.1016\/j.nmd.2018.02.005","article-title":"Sporadic acute benign calf myositis: Systematic literature review","volume":"28","author":"Capoferri","year":"2018","journal-title":"Neuromuscul. Disord."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1186\/s13052-021-01002-x","article-title":"Management and outcome of benign acute childhood myositis in pediatric emergency department","volume":"47","author":"Brisca","year":"2021","journal-title":"Ital. J. Pediatr."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1016\/j.arcped.2022.08.009","article-title":"Benign acute childhood myositis: A 5-year retrospective study","volume":"29","author":"Costa","year":"2022","journal-title":"Arch. P\u00e9diatrie"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"399","DOI":"10.1007\/BF02731735","article-title":"Benign acute childhood myositis","volume":"72","author":"Rajajee","year":"2005","journal-title":"Indian J. Pediatr."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Kosmeri, C., Papasavva, M.E., Kyrkou, A., Gketsi, V., Siomou, E., Ladomenou, F., and Makis, A. (2025). Influenza-Associated Benign Acute Childhood Myositis During the 2024\u20132025 Season: A Retrospective Multicenter Study. Children, 12.","DOI":"10.3390\/children12101333"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1097\/INF.0000000000004320","article-title":"Clinical Characteristics of 118 Pediatric Patients With Acute Benign Myositis Associated With Influenza A Virus Infection","volume":"43","author":"Jiang","year":"2024","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1097\/PEC.0000000000000830","article-title":"Outcome of Benign Acute Childhood Myositis: The Experience of 2 Large Tertiary Care Pediatric Hospitals","volume":"34","author":"Rosenberg","year":"2018","journal-title":"Pediatr. Emerg. Care"},{"key":"ref_16","unstructured":"Walker, H.K., Hall, W.D., and Hurst, J.W. (1990). Creatine Kinase. Clinical Methods: The History, Physical, and Laboratory Examinations, Butterworths. [3rd ed.]."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"S357","DOI":"10.14309\/00000434-201510001-00820","article-title":"Masquerading Myositis: An Important Cause of Elevated LFTs: 820","volume":"110","author":"Dueker","year":"2015","journal-title":"Off. J. Am. Coll. Gastroenterol.|ACG"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1097\/RHU.0000000000000038","article-title":"Serum transaminases are frequently elevated at time of diagnosis of idiopathic inflammatory myopathy and normalize with creatine kinase","volume":"20","author":"Mathur","year":"2014","journal-title":"J. Clin. Rheumatol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1016\/j.ajem.2020.04.061","article-title":"Patterns of transaminase elevation in rhabdomyolysis versus acetaminophen toxicity","volume":"44","author":"Maskell","year":"2021","journal-title":"Am. J. Emerg. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"294","DOI":"10.1007\/s13181-010-0075-9","article-title":"Liver Aminotransferases Are Elevated with Rhabdomyolysis in the Absence of Significant Liver Injury","volume":"6","author":"Weibrecht","year":"2010","journal-title":"J. Med. Toxicol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1007\/s00431-025-06116-6","article-title":"Benign acute childhood myositis in the COVID-19 Era: How does it compare to influenza?","volume":"184","author":"Chen","year":"2025","journal-title":"Eur. J. Pediatr."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1056\/NEJMra0801327","article-title":"Rhabdomyolysis and Acute Kidney Injury","volume":"361","author":"Bosch","year":"2009","journal-title":"N. Engl. J. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"377","DOI":"10.1097\/01.md.0000188565.48918.41","article-title":"Rhabdomyolysis: An evaluation of 475 hospitalized patients","volume":"84","author":"Melli","year":"2005","journal-title":"Medicine"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1020","DOI":"10.3748\/wjg.v26.i10.1020","article-title":"Abnormal liver function tests associated with severe rhabdomyolysis","volume":"26","author":"Lim","year":"2020","journal-title":"World J. Gastroenterol."}],"container-title":["Pediatric Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2036-7503\/18\/2\/47\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T10:01:54Z","timestamp":1775124114000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2036-7503\/18\/2\/47"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,31]]},"references-count":24,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["pediatric18020047"],"URL":"https:\/\/doi.org\/10.3390\/pediatric18020047","relation":{},"ISSN":["2036-7503"],"issn-type":[{"value":"2036-7503","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,31]]}}}