Lymphangioma. An otolaryngologic perspective.

Lymphangiomas are relatively rare congenital hamartomas of the lymphatic system usually diagnosed in infancy and early childhood. Although the precise pathogenesis has not been clearly defined, abnormal development leads to formation of fluid-filled sinuses lined by vascular endothelium. In the head and neck, lymphangioma may encroach on vital structures and infiltrate surrounding tissues making complete surgical removal difficult. A number of children (n = 137) with lymphangioma have been treated at Texas Children's Hospital from 1972-1985. In 45 (33%), the tumors were diagnosed at birth and in an additional 51 (37%), by two years of age. Commonly affected areas included the head and neck (45%), trunk (26%), and axilla (17%). Mediastinal involvement occurred in 4%. Surgical removal was the preferred treatment method and with complete removal the recurrence rate was 6%; known incomplete removal increased this rate to 35%. Although lymphangiomas are slow growing, early removal was preferable: recurrences increased as the time interval between tumor identification and surgical intervention lengthened. Size fluctuation with a history of infection, another unfavorable prognostic factor, also increased recurrence rate.

Analysis of responses to dopamine in the mesenteric vascular bed of the cat.

Responses to dopamine were investigated in the feline mesenteric vascular bed under conditions of controlled blood flow. Intra-arterial injections of dopamine in doses of 3, 10 and 30 microgram caused biphasic changes in mesenteric arterial perfusion pressure. The pressor component of the biphasic response was blocked whereas the depressor component was enhanced after administration of phenoxybenzamine in a dose that reversed vasoconstrictor responses to norepinephrine. Depressor responses to dopamine in phenoxybenzamine treated animals were not blocked by propranolol or atropine in doses that inhibited responses to isoproterenol or acetylcholine or by indomethacin in a dose that inhibited responses to the prostaglandin precursor arachidonic acid. Depressor responses to dopamine were inhibited by bulbocapnine in a dose that was without significant effect on depressor responses to isoproterenol or nitroglycerin. The inhibitory effects of bulbocapnine were reversible and vasodepressor response to dopamine returned to control levels 15-30 min after the bulbocapnine infusion was discontinued. These data suggest that the pressor effects of dopamine in the feline mesenteric vascular bed are due to activation of alpha adrenergic receptors whereas the vasodilator activity results from activation of vascular dopamine receptors that are distinct from beta adrenergic or cholinergic receptors and does not involve the release of dilator prostaglandin.

Blockade of vasoconstrictor responses by prostacyclin (PGI2), PGE2, and PGE1 in the rabbit hindquarters vascular bed.

The effects of infusions of prostacyclin (PGI2), PGE2 and PGE1 on responses to pressor hormones and sympathetic nerve stimulation were investigated in the hindquarters vascular bed of the rabbit. During infusions of PGI2, PGE2 and PGE1 vasoconstrictor responses to norepinephrine, nerve stimulation and angiotensin II were decreased. Responses to the pressor hormones and nerve stimulation were decreased to a similar extent by PGI2 and responses returned to control value 30 min after the infusion. During infusions of PGE2 and PGE1 responses to nerve stimulation were decreased to a somewhat greater extent than responses to pressor hormones and the inhibitory action of these substances had a longer duration of action than PGI2. Indomethacin in doses that blocked depressor responses to arachidonic acid was without consistent effect on responses to nerve stimulation and pressor hormones. The present data show that E series prostaglandins and PGI2 possess the ability to modulate responses to nerve stimulation and pressor hormones; however, experiments with indomethacin suggest that endogenous prostaglandins do not modulate vasoconstrictor responses in the rabbit hindquarters.