Between Portal and Systemic Veins. Sites are:
1. At the lower end of oesophagus – esophageal tributaries of left gastric vein ( portal) communicate with oesophageal tributaries of hemiazygous veins (systemic).
2. At the lower end of rectum and anal canal – superior rectal vein (portal) communicates with middle and inferior rectal veins (systemic).
3. Anterior abdominal (around umbilicus):
- Paraumbilical vein (portal) communicates with systemic veins in epigastric, lateral thoracic, intercostal and lumbar veins.
- Paraumbilical vein (portal) communicates with diaphragmatic veins (systemic) by a number of small veins, called accessory portal system of Sappey.
4. At bare area of liver – portal radicles of liver communicates with diaphragmatic veins (systemic)
5. At retroperitoneal site – the splenic and colic veins (portal) communicate with renal veins and other tributaries of IVC by small veins, called veins of Retzius.
6. At the fissure for ligamentum venosum, rarely, persistent ductus venosus establishes direct portocaval anastomosis (in fetal life, left branch of portal vein at the porta hepatitis communicates with IVC via ductus venosus. After birth, ductus venosus is fibrosed to form ligamentum venosum).
It consists of central arteriole from which numerous capillaries radiate, looks kike spider legs. Size varies from pinhead to 1-2 mm (sometimes cm). These are found along the area of SVC, commonly in neck, face, chest, and dorsum of hand and above nipple lines, cause of which is not known. It blanches on pressure, may pulsate if large. Better seen with glass slide or pinhead.
Causes of spider angioma:
- Rarely present in normal people (2%), one to two in number, common in children. If >2 in number, it is usually pathological, especially in male than female.
- Pregnancy (usually in the third trimester, disappears after 2 months of delivery)
- CLD, commonly in alcoholic cirrhosis (disappears with improvement of liber function, appearance of new spider indicates deterioration of liver function).
- Viral hepatitis ( transient).
- Estrogen therapy and estrogen-containing oral contraceptive pill.
- Rarely, in rheumatoid arthritis, thyrotoxicosis.
Mechanism of spider angioma:
- Due to hyperdynamic circulation
- Excess estrogen level (due to reduced metabolism by the liver).
Differential diagnosis of spider angioma:
- Purpura (spontaneous bleeding into skin and mucous membrane, does not blanch on pressure and there is progressive color change)
- Hereditary hemorrhagic telangiectasia
- Campbell de Morgan Spots
- Venous stars
These are 2-3 cm lesions that occur on dorsum of foot, leg, back and lower chest. Caused by elevated venous pressure amd are usually found overlying the main tributary of large veins. Do not blanch on pressure and blood flow if from periphery to the center of lesion (opposite to spider angioma).
Redness in thenar and hypothenar eminence and pulp of fingers. Blanches of pressure. With glass slide, flushes synchronously with pulse. Causes of palmar erythema:
- Normal people, may be familial
- CLD (commonly alcoholic cirrhosis)
- Prolonged rheumatoid arthritis
- Chronic leukemia
- Febrile illness.
Mechanism of palmar erythema:
- Hyperdynamic circulation
- Probably, high estrogen ( controversial)
Reference: Clinical Medicine – ABM Abdullah