{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:41:56Z","timestamp":1760060516691,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,9,1]],"date-time":"2025-09-01T00:00:00Z","timestamp":1756684800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Reports"],"abstract":"<jats:p>Background and Clinical Significance: Acquired angioedema (AAE) is a rare and potentially life-threatening condition characterized by acquired deficiency of C1-inhibitor (C1-INH) resulting in hyperactivation of the classical complement pathway. AAE occurs in association with malignancies or autoimmune diseases. Infectious triggers are rarely encountered, and the underlying mechanisms have yet to be completely clarified. Case Presentation: This case involves a previously healthy 19-year-old male who was admitted with Mycoplasma pneumonia and oral ulcers, subsequently developing unilateral facial angioedema. Laboratory studies demonstrated reduced C4, decreased levels and activity of C1-INH, and reduced C1q, all consistent with acquired C1-INH deficiency. These findings were attributed to the presence of cold agglutinins, which are frequently observed in Mycoplasma pneumoniae infections. Following treatment with icatibant, a bradykinin B2 receptor antagonist, the patient\u2019s angioedema resolved rapidly. An exhaustive workup found no evidence of underlying systemic disorders, and the patient did not experience any angioedema attacks following resolution of the infection. Conclusions: The presence of cold agglutinins, commonly associated with Mycoplasma infections, can precipitate a decline in C1-INH levels, resulting in complement pathway dysregulation. This disruption leads to an excess of bradykinin, followed by increased vascular permeability and localized edema.<\/jats:p>","DOI":"10.3390\/reports8030164","type":"journal-article","created":{"date-parts":[[2025,9,1]],"date-time":"2025-09-01T08:28:15Z","timestamp":1756715295000},"page":"164","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Acquired Angioedema Related to Transient C1- Inhibitor Deficiency Triggered by Mycoplasma pneumoniae Infection: A Case Report"],"prefix":"10.3390","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-0367-8656","authenticated-orcid":false,"given":"Athanasia-Marina","family":"Peristeri","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-6191-1022","authenticated-orcid":false,"given":"Olympia","family":"Akritidou","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-2968-6463","authenticated-orcid":false,"given":"Anna","family":"Nikopoulou","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0001-1114-7222","authenticated-orcid":false,"given":"Konstantina","family":"Theodoridou","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michail","family":"Leontakianakos","sequence":"additional","affiliation":[{"name":"Pulmonary Department, Aristotle University of Thessaloniki, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Christina Chrysanthi","family":"Theocharidou","sequence":"additional","affiliation":[{"name":"1st Intensive Care Unit, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Georgios","family":"Pilianidis","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, G. Papanikolaou General Hospital of Thessaloniki, 57010 Thessaloniki, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1007\/s12016-016-8541-z","article-title":"Angioedema Phenotypes: Disease Expression and Classification","volume":"51","author":"Wu","year":"2016","journal-title":"Clin. Rev. Allergy Immunol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"108819","DOI":"10.1016\/j.clim.2021.108819","article-title":"Where we are with acquired angioedema due to C1 inhibitor deficiency: A systematic literature review","volume":"230","author":"Shi","year":"2021","journal-title":"Clin. Immunol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1186\/1710-1492-6-14","article-title":"Acquired angioedema","volume":"6","author":"Cicardi","year":"2010","journal-title":"Allergy Asthma Clin. Immunol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1097\/00005792-197907000-00004","article-title":"Acquired C1 esterase inhibitor deficiency and angioedema: A review","volume":"58","author":"Gelfand","year":"1979","journal-title":"Medicine"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1186\/1710-1492-6-24","article-title":"2010 International consensus algorithm for the diagnosis, therapy and management of hereditary angioedema","volume":"6","author":"Bowen","year":"2010","journal-title":"Allergy Asthma Clin. Immunol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e9","DOI":"10.1016\/j.ejim.2015.11.011","article-title":"Extra-pulmonary manifestations associated with Mycoplasma pneumoniae pneumonia in adults","volume":"29","author":"Kawai","year":"2016","journal-title":"Eur. J. Intern. Med."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.jdcr.2021.01.004","article-title":"Mycoplasma pneumoniae-associated angioedema","volume":"9","author":"Theiler","year":"2021","journal-title":"JAAD Case Rep."},{"key":"ref_8","first-page":"513","article-title":"Angioedema due to acquired C1-esterase inhibitor deficiency in a patient with Helicobacter pylori infection","volume":"37","author":"Farkas","year":"1999","journal-title":"Z Gastroenterol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"773","DOI":"10.3949\/ccjm.74.11.773","article-title":"A 19-year-old man with oral ulcers, pulmonary infiltrates, and rash","volume":"74","author":"Buencamino","year":"2007","journal-title":"Clevel. Clin. J. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"239","DOI":"10.1016\/j.jaad.2014.06.026","article-title":"Mycoplasma pneumoniae-induced rash and mucositis as a syndrome distinct from Stevens-Johnson syndrome and erythema multiforme: A systematic review","volume":"72","author":"Canavan","year":"2015","journal-title":"J. Am. Acad. Dermatol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"39","DOI":"10.5114\/dr.2024.140803","article-title":"The role of Mycoplasma pneumoniae in dermatological diseases","volume":"111","author":"Podraza","year":"2024","journal-title":"Dermatol. Rev. Dermatologiczny"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"673","DOI":"10.1111\/j.1365-4632.2009.04154.x","article-title":"Mycoplasma pneumoniae-induced cutaneous disease","volume":"48","author":"Schalock","year":"2009","journal-title":"Int. J. Dermatol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1573","DOI":"10.1007\/s10067-008-0990-1","article-title":"Non-episodic angioedema associated with eosinophilia following Mycoplasma pneumoniae infection","volume":"27","author":"Stockner","year":"2008","journal-title":"Clin. Rheumatol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1007\/s12016-021-08841-w","article-title":"Differences and Similarities in the Mechanisms and Clinical Expression of Bradykinin-Mediated vs. Mast Cell\u2013Mediated Angioedema","volume":"61","author":"Maurer","year":"2021","journal-title":"Clin. Rev. Allergy Immunol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1132","DOI":"10.1016\/j.jaip.2018.04.022","article-title":"Angioedema Due to Bradykinin Dysregulation","volume":"6","author":"Cicardi","year":"2018","journal-title":"J. Allergy Clin. Immunol. Pract."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Lima, H., Zheng, J., Wong, D., Waserman, S., and Sussman, G.L. (2023). Pathophysiology of bradykinin and histamine mediated angioedema. Front. Allergy., 4.","DOI":"10.3389\/falgy.2023.1263432"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1111\/j.1523-5378.2009.00651.x","article-title":"Autoimmune angioneurotic edema in a patient with Helicobacter pylori infection","volume":"14","author":"Mukeba","year":"2009","journal-title":"Helicobacter"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1007\/s00431-003-1250-7","article-title":"Acquired angioedema and Helicobacter pylori infection in a child","volume":"162","author":"Varvarovska","year":"2003","journal-title":"Eur. J. Pediatr."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1080\/10245330701445392","article-title":"Primary chronic cold agglutinin disease: An update on pathogenesis, clinical features and therapy","volume":"12","author":"Berentsen","year":"2007","journal-title":"Hematology"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"S133","DOI":"10.1164\/ajrccm\/154.4_Pt_2.S133","article-title":"Carbohydrate recognition by Mycoplasma pneumoniae and pathologic consequences","volume":"154","author":"Feizi","year":"1996","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"627","DOI":"10.1046\/j.1537-2995.1991.31791368339.x","article-title":"Sia-b1 and I antigens recognized by Mycoplasma pneumoniae-induced human cold agglutinins","volume":"31","author":"Kreft","year":"1991","journal-title":"Transfusion"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1114","DOI":"10.1182\/blood-2013-02-474437","article-title":"Cold agglutinin disease","volume":"122","author":"Swiecicki","year":"2013","journal-title":"Blood"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1053\/j.seminhematol.2018.04.002","article-title":"Complement Activation and Inhibition in Autoimmune Hemolytic Anemia: Focus on Cold Agglutinin Disease","volume":"55","author":"Berentsen","year":"2018","journal-title":"Semin. Hematol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"S113","DOI":"10.1016\/j.anai.2022.08.821","article-title":"Like father, like son: Hereditary angioedema (hae) with low C1q levels","volume":"129","author":"Suresh","year":"2022","journal-title":"Ann. Allergy Asthma Immunol."}],"container-title":["Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2571-841X\/8\/3\/164\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:36:55Z","timestamp":1760035015000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2571-841X\/8\/3\/164"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,1]]},"references-count":24,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["reports8030164"],"URL":"https:\/\/doi.org\/10.3390\/reports8030164","relation":{},"ISSN":["2571-841X"],"issn-type":[{"type":"electronic","value":"2571-841X"}],"subject":[],"published":{"date-parts":[[2025,9,1]]}}}