A 53-year-old woman was referred for evaluation of recurrent angioedema that did not respond to several therapeutic modalities, including diuretics. Unusual features in her history included involvement of her abdominal wall and all 4 extremities with no pulmonary edema. Physical examination revealed nonpitting edema of her lower and upper extremities, as well as an indurated abdominal wall. Systemic capillary leak syndrome was considered in the differential diagnosis. Pending the outcome of her testing, the prophylactic regimen for idiopathic capillary leak syndrome was initiated: terbutaline sulfate, 5 mg 5 times daily, and theophylline, 200 mg twice daily.1 Evaluation included a normal C1 esterase inhibitor level; serum immunofixation electrophoresis showed a monoclonal IgGκ band (commonly seen in systemic capillary leak syndrome), which was eventually diagnosed as monoclonal gammopathy of unknown significance. Given the abnormal appearance of her abdominal wall, amyloidosis was considered. Results from a fine-needle aspiration were negative for amyloid. Findings from an abdominal wall punch biopsy were consistent with lymphedema, with scattered dilated capillary lymphatic spaces in the superficial and deep dermis. Evaluation for a cause of lymphedema included an evaluation for malignant neoplasms with a full-body computed tomographic scan showing axillary lymphadenopathy. An axillary lymph node biopsy specimen was negative for malignant cells. One week after the initiation of terbutaline and theophylline therapies, there was a marked improvement of her lymphedema. Her weight decreased by 14 kg after 10 months of treatment (Figure, A and B). There was a direct correlation identified between the dose of terbutaline and the degree of lymphedema. Attempts to wean the terbutaline from 5 tablets to less than 3 tablets daily resulted in increased edema and weight, which would resolve by resuming the higher dose (Figure, C).