Teaching Case

A middle-aged male presented to the emergency department because of crampy abdominal pain and repeated fainting. Medical history included appendectomy, cigarette smoking, hypercholesterolemia, and an unremarkable recent sports medicine exercise test. Physically, he was found hypotensive (80/50 mmHg), sweating but afebrile, without peritonism. A laboratory revealed haemoconcentration (haemoglobin 19 g/dL, haematocrit 60%), elevated creatinine and C-reactive protein.

Initial chest radiograph (Fig.1), electrocardiogram and transthoracic echocardiography (not shown) revealed normal findings. Hypotension worsened despite resuscitation including cristalloid infusion, hydrocortisone and noradrenaline.
Urgent CT excluded pulmonary thromboembolism, acute pleuropulmonary, airway, aortic and mediastinal abnormalities (Fig.2). Abdominal images (Fig.3) showed a constellation of findings resembling a mild form of the traumatic hypoperfusion complex, including marked, homogeneous contrast enhancement of both renal parenchymas, normal-sized adrenals with subtle pronounced enhancement, gastric fluid overdistension, poor inhomogeneous splenic enhancement, flattened inferior vena cava with hypointense “halo sign” at its retrohepatic tract, collapsed renal veins. Additionally, the collapsed colon (fig.4) showed diffuse, moderate circumferential mural thickening with mucosal enhancement and mural hypoattenuation from submucosal oedema.
Normal faeces and gastric content excluded gastrointestinal bleeding. Oliguria and progressive calf swelling were noted, with MRI findings (Fig.5) of oedematous muscles and fascial fluid.
The clinical and biochemical abnormalities, consistent with systemic capillary leak syndrome, regressed and ultimately normalised during intensive therapy.

Initially described in 1960, the systemic capillary leak syndrome (SCLS, Clarkson’s disease) is a rare, potentially life-threatening entity characterized by recurrent unpredictable episodes of hypovolemic shock resulting from capillary leakage of plasma fluid and proteins into the interstitial space. Less than 150 cases have been reported, some of them associated with autoimmune disorders such as Sjogren’s syndrome. The typical patient is a previously healthy middle-aged (median age 44 years) Caucasian adult, with a slight male predominance. Attacks vary in severity and patients experience sudden development of hypotension and oedema, frequently after nonspecific prodromic symptoms such as malaise, fatigue and myalgias, sometimes vomiting and fever. Characteristic laboratory findings include hypoalbuminemia, hemoconcentration, leukocytosis, raised serum creatinine and creatine-phosphokinase. The hypothesized pathophysiology involves a diffuse transient endothelial hyperpermeability; the monoclonal paraprotein present in 80-90% of patients could possibly bind a factor involved in barrier function. During attacks, patients risk ischemia-induced organ failure, rhabdomyolysis, muscle compartment syndrome and venous thromboembolism. Plasma extravasation and haemodynamic collapse are quickly reversible with massive fluid mobilization from tissues into circulation and diuresis: at this time pulmonary oedema may develop from cardiovascular overload [1-7].
SCLS should be clinically considered in shocked patients without cardiac dysfunction, particularly if worsening after aggressive intravenous fluid resuscitation. Negative microbiological and immunological studies allow excluding other causes such as sepsis, anaphylaxis and angioedema. The reported imaging findings of SCLS are generally limited to inconstant pleural and pericardial effusions. However, as in this case subtle CT signs may be noted, similar to the hypoperfusion complex reported in traumatic or haemorrhagic shock which reflects altered circulation in response to hypovolemia to preserve renal perfusion by shifting flow away from the splanchnic circulation. These signs include: a) diffusely thickened bowel loops with submucosal oedematous hypoattenuation and preserved mucosal enhancement (a finding which is reversible and does not cause symptoms); b) flattened infrahepatic inferior vena cava (IVC) and renal veins; c) sometimes the “halo sign” representing extracellular fluid surrounding the collapsed retrohepatic IVC; d) markedly increased, symmetric renal and adrenal enhancement; and e) diminished splenic enhancement (20 Hounsfield lower than that of the liver) [1-10].
Between episodes, SCLS patients are asymptomatic and receive prophylactic therapy with theophylline or verapamil, to reduce severity and frequency of attacks. Their prognosis is uncertain albeit a 70% rate at 10 years has been reported [1-7].