Case report describes chronic capillary leak syndrome responding to IVIG

A single-patient case report published in Allergy, Asthma & Clinical Immunology describes a 39-year-old woman whose fifteen-year history of episodic limb swelling and profuse sweating improved after treatment with high-dose intravenous immunoglobulin. The report, authored by Eric McMullen and Karen Binkley, was published on 22 October 2026 as an open-access case report.

The woman’s episodes involved symmetric swelling of the limbs and heavy sweating. According to the report, the episodes were chronic and did not include hypotension or itching. Antihistamines and corticosteroids had been tried over several years without response, and the episodes persisted throughout that period.

These findings pointed clinicians toward systemic capillary leak syndrome associated with monoclonal gammopathy, a form of the disorder also known as Clarkson’s disease.

Systemic capillary leak syndrome is described in the report as a rare disorder characterized by transient plasma extravasation due to endothelial barrier dysfunction, in which the lining of small blood vessels becomes abnormally permeable and plasma fluid escapes into surrounding tissue. The condition may occur idiopathically or in association with monoclonal gammopathy.

Treatment with monthly high-dose intravenous immunoglobulin at a dose of 2 grams per kilogram was initiated. The report states that improvement was noted by the fourth infusion, with complete resolution of swelling and a marked reduction in sweating after five months of therapy. The treatment was described as well tolerated, with mild infusion-related headache as the only noted adverse effect.

The authors emphasize that this case illustrates that monoclonal gammopathy-associated capillary leak syndrome may present as a chronic disorder without the classic triad of features. In this patient, the presentation lacked the hypotensive episodes often emphasized in descriptions of the syndrome, and the dominant features were recurrent edema and sweating over many years.

Based on this single case, the authors suggest that in selected patients with mild or atypical presentations, a therapeutic trial of intravenous immunoglobulin may be considered. As the report’s conclusions state, the case indicates that this form of the syndrome may respond favorably to such therapy, although the observation comes from one patient and cannot establish how broadly the finding applies.

The published version of this article is being shared early to provide faster access to peer-reviewed, accepted research, and the publisher notes that this version is subject to further edits before the final version of record replaces it.

Subject of Research: A case report of chronic monoclonal gammopathy-associated systemic capillary leak syndrome treated with intravenous immunoglobulin

Article Title: Chronic systemic capillary leak syndrome with monoclonal kappa light chain gammopathy responsive to intravenous immunoglobulin: a case report

Article References: McMullen, E., & Binkley, K. (2026). Chronic systemic capillary leak syndrome with monoclonal kappa light chain gammopathy responsive to intravenous immunoglobulin: a case report. Allergy, Asthma & Clinical Immunology. https://doi.org/10.1186/s13223-026-01073-7

Image Credits: AI Generated

DOI: 10.1186/s13223-026-01073-7

Keywords: systemic capillary leak syndrome, Clarkson's disease, monoclonal gammopathy, kappa light chain, intravenous immunoglobulin, IVIG, case report, hemoconcentration, edema, endothelial barrier dysfunction, rare disease, immunology