Spider Naevi: Pathogenic Threshold and Associated Conditions
Five or more spider naevi should be considered pathogenic and warrant investigation for chronic liver disease, though this finding has limited sensitivity as many patients with cirrhosis have fewer than five lesions. 1
Pathogenic Number
The threshold of ≥5 spider naevi is more specific for liver disease, though only 2.5% of healthy children aged 5-15 years have more than five spider naevi, compared to a higher proportion in those with chronic liver disease 1
In children with chronic liver disease, only 4 of 34 (12%) had five or more spider naevi, indicating that the absence of multiple spider naevi does not exclude significant liver pathology 1
Among children with cirrhosis specifically, 8 of 10 (80%) had at least one spider naevus, but the total number was often below the five-lesion threshold 1
The presence of "extensive spider naevi" is listed as a clinical sign warranting screening for harmful alcohol consumption and alcoholic liver disease 2
Prognostic Significance in Liver Disease
Spider naevi carry independent prognostic value in alcoholic liver disease, with a relative risk of mortality of 3.3 over one year 2
The prevalence of spider naevi in cirrhosis is approximately 30-47%, with higher rates associated with more severe liver dysfunction 3, 4
Patients with spider naevi have significantly higher Child-Pugh scores (8.35 vs 7.47, p=0.005) and MELD scores (9.91 vs 7.43, p=0.008) compared to cirrhotic patients without spider naevi 4
However, the presence of spider naevi alone does not predict worse survival in cirrhotic patients (p=0.951), unlike subcutaneous collateral vessels which do predict mortality 4
Conditions Associated with Spider Naevi
Chronic Liver Disease (Primary Association)
Alcoholic liver disease is strongly associated with spider naevi, with 54.84% of cirrhotic patients with spider naevi having alcohol abuse history versus 26.67% without spider naevi (p<0.001) 4
Spider naevi have 95% specificity for liver cirrhosis and are considered a characteristic cutaneous manifestation 3
The pathogenesis involves decreased testosterone, elevated estradiol, hyperdynamic circulation, substance-P, and vascular endothelial growth factor leading to angiogenesis and vasodilation 3
Physiologic States
Pregnancy is associated with spider naevi due to the hyperestrogenic state, and these lesions typically appear as palmar erythema and spider naevi become more visible 2
Normal pregnancy can mimic chronic liver disease findings, with spider naevi likely increased due to hormonal changes and hyperdynamic circulation 2
Other Endocrine Conditions
- Thyrotoxicosis is frequently associated with spider naevi alongside liver cirrhosis and pregnancy as the three main conditions 3
Age-Related Occurrence
In healthy children, 38% have at least one spider naevus, with prevalence increasing with age 1
Most spider naevi in children are located on the hands and very few exceed 5mm in size 1
Distribution and Characteristics
Spider naevi typically occur in the territory of the superior vena cava: face (nose, lips, forehead), upper chest, and arms 3
They consist of a central arteriole with surrounding radiating vascular channels resembling spider legs, hence the name 3
Grading ranges from 1+ (readily recognizable with body, legs, and erythema) to 4+ (visible pulsations with raised central punctum and many obvious radiating vessels) 3
Clinical Pitfalls
The absence of spider naevi does not exclude chronic liver disease or even cirrhosis, as sensitivity is limited even in advanced disease 2, 1
Physical examination findings including spider naevi have considerable heterogeneity when assessed by different examiners, requiring cautious interpretation 2
Spider naevi should prompt evaluation for other stigmata of liver disease including palmar erythema, testicular atrophy, gynecomastia, Dupuytren's contracture, parotid enlargement, and muscle wasting 2
When spider naevi are present with digital clubbing, consider alternative diagnoses such as congenital heart disease, interstitial lung disease, or pulmonary vascular disease rather than simple chronic liver disease 2, 5