Sildenafil (Viagra) appears to lessen severe lymphatic malformations in children, according to researchers who have used the drug successfully in three pediatric patients.

The first patient who presented to Glenda L. Swetman, MD, from Stanford University in Palo Alto, Calif., and colleagues was a 10-week-old girl with a congenital, nonpulsatile, violaceous nodular plaque. At age 5 months, congestive heart failure developed and an echocardiogram showed pulmonary hypertension with no congenital anomalies.

Despite initial indications of improvement using conservative measures, her condition worsened. At 9 months, cardiac catheterization confirmed idiopathic pulmonary hypertension and sildenafil was started, according to a letter published in the Jan. 26 issue of the New England Journal of Medicine.

Over time, the malformation diminished and at four months after treatment began, the enlargement of the right chest and arm had become a small, thin plaque. A magnetic resonance imaging (MRI) study of the heart showed only minimal residual malformation.

Based on this outcome, a pilot study was undertaken and two additional children with disabling lymphatic malformations were given sildenafil for 12-week periods.

Lymphatic malformations are uncommon congenital vascular anomalies that can obstruct vital organs and interfere with their function, and can lead to recurrent infection and disfigurement, the authors noted. "Current procedural treatments are only partially successful, and lymphatic malformations often recur."

The first patient in the pilot was a 12-month-old boy with lymphatic malformations involving the orbit and upper eyelid that obstructed his vision. Despite the fact that improved opening of the eye was seen at three weeks, debulking was performed to avoid amblyopia.

By the end of the 12-week period, the ability of the child to open the eye had increased by 25%. When the medication was stopped, tissue enlargement returned.

The second child was a 15-month-old girl with three large lymphatic malformations. She had partial improvement with sclerotherapy prior to beginning the course of medication.

During 12 weeks of sildenafil treatment, the malformations diminished by about 75%. One on her back looked to the physicians as though it had deflated, leaving only sagging skin. As before, mild enlargement of the malformations were seen after the medication was discontinued.

There were no significant adverse effects seen from treatment. In both cases, the families decided to continue using the medication after the 12-weeks was completed.

The authors suggested that the medicine might act by relaxing smooth muscles resulting in decompression of the cyst. This relaxation may also allow secondary lymphatic spaces to reopen. Finally, sildenafil may normalize endothelial dysfunction in the lymphatic system.

"The observations described suggest that sildenafil represents an encouraging, propitious treatment for lymphatic malformations, used as monotherapy or with other treatments," wrote the authors.

A double-blind, placebo-controlled study has already begun to see if these results continue in a larger population.