Treatment of cystic hygroma in a young infant through multidisciplinary approach involving sirolimus, sclerotherapy, and debulking surgery.

Introduction

Cystic hygromas are macrocystic lymphatic malformations that develop during the sixth gestational week.1, 2 Cystic hygromas (CH) mostly present in the neck and comprise 20% to 25% of cervical lymphatic tumors. Mainstay treatment of CH involves complete surgical resection and sclerotherapy. Sclerotherapy has been consistently chosen over the other modalities. Oosthuizen et al reported a management algorithm that incorporated sclerotherapy and surgery in the management of cervicofacial lymphatic malformation. Sclerotherapy has been consistently employed in the management of lymphatic malformations with notable reduction (30%) and sometimes complete eradication of cystic hygrma. Intralesional bleomycin helped achieve complete clinical remission in 47% of patients, greater than 50% reduction in 35.8%, and less than 50% reduction in 17.1% in a 70-patient trial. However, sclerotherapy has many adverse effects including swelling at the site of the lesion, scarring, pulmonary fibrosis, hemorrhage, and infection. Additionally, sclerotherapy may be futile in the management of cysts not accessible for injections. Therefore, we propose a more effective approach that involves combining sirolimus to the aforementioned modalities. Sirolimus inhibits mammalian target of rapamycin (mTOR).7, 8, 9 Specifically, sirolimus binds to FK506 to form a protein complex that avidly binds to mTOR resulting in dephosphorylation and deactivation of p70S6 kinase, which, in turn, results in the decrease of vascular endothelial growth factor C, a stimulant of lymphatic endothelial cells. Blatt et al reported the first successful use of sirolimus in the management of kaposiform hemangioendothelioma.

Herein, we present remarkable reduction of extensive cystic hygroma in a 15-month-old infant through a debulking surgery followed by the administration of sirolimus in addition to reduced course of sclerotherapy.

Case report

An 8-month-old boy was hospitalized since his birth for extensive cystic hygroma. The mother is a 47-year-old healthy woman. She is gravida 9, para 6, plus 2 with no consanguinity, no chronic disease in the family, and no history of congenital anomalies. Her pregnancy was unremarkable with regular follow ups until the antenatal presentation of an enormous neck mass and polyhydramnios during the 27th gestational week. She went into labor in 35th week and underwent emergency cesarean section and along with extrauterine intrapartum airway intervention (EXIT) due to extensive neonatal neck mass that would potentially compromise the neonate's airway. The EXIT procedure is usually done for any fetus with a large neck mass before cutting the umbilical cord.

The patient exhibited no dysmorphism, with the large neck mass mainly involving the right side of the neck. His tongue was also involved, posing a challenge for conventional treatment with sclerotherapy. His chest, abdomen, cardiac, genitalia, and back were unremarkable. The birth weight was 3.08 kg. Baseline magnetic resonance imaging (MRI) (Fig 1) done 2 days after his birth showed a mass with a volume of 370 mL. The diagnosis was cystic hygroma.

Fig 1

MRI of the face before treatment 2 days after birth. Axial T2 image with fat suppression shows numerous large bright cysts with fluid-fluid level indicating hemorrhage in the cysts. This extends through all tissues from skin on one side to the skin on the other side. The malformation volume was about 370 mL. Axial T1 image at the level of the airway confirms high signal indicating blood in the cysts.

The patient underwent 4 sclerotherapy sessions with a 1-week period between sessions a week after his birth. The sclerosing agents used include alcohol, polidocanol, and doxycycline. He then underwent debulking surgery for the cystic hygroma and gastrostomy to facilitate the administration of sirolimus. Subsequently, he underwent one more sclerotherapy session for a total of 5 sclerotherapy sessions. The cystic hygroma persisted and the veins within the tumor became sclerosed and hence difficult for injection; therefore, sclerotherapy was no longer an option for management. He was then started on sirolimus when he was 1 month old with an initial dose of 0.07 mg/kg given twice daily through gastrostomy tube. Sirolimus level was monitored and maintained within a range of (0.004–0.01 mg/kg). Ten days after starting sirolimus, MRI showed visual 70% to 80% improvement (about 74–110 mL). Follow-up ultrasound scans showed a decrease in the cystic components of the hygroma mass. After the administration of sirolimus for 15 months, the size of the tumor decreased to 90% of its original size before treatment, leaving a residual of 10 to 20 mL with a 79- to 110-mL reduction of original volume of 370 mL of cysts that were in the cheek, temple, and tongue that were not treated with sirolimus (Fig 2, Fig 3, Fig 4, Fig 5, Fig 6, Fig 7, Fig 8). The patient had laryngomalacia because of the mass effect of the cystic hygroma that compromised the airway. He is a potential candidate for future plastic surgeries to remove redundant skin.

Fig 2

Patient at birth with large cystic hygroma involving neck and tongue.

Fig 3

Patient after 2 sclerotherapies at 28 days of age with regression in the size of the cystic hygroma.

Fig 4

Patient after surgical debulking at 45 days of age along with prior 2 sclerotherapy sessions but no sirolimus yet.

Fig 5

Three months later, the patient after starting sirolimus.

Fig 6

Patient 8 months after starting sirolimus with remarkable reduction in the size of the cystic hygroma.

Fig 7

Patient after 15 months of sirolimus therapy with notable reduction in cystic hygroma.

Fig 8

MRI of the face after sirolimus treatment for 10 months: The estimated residual volume is about 10 to 30 mL. Notably, there is resolution of untreated areas in the tongue and cheeks.

Discussion

Cystic hygromas may potentially present anywhere in the body. Some of the common sites include the cervicofacial region (80% of cases), mediastinum, beneath the tongue, axilla, and groin. Sixty percent of CH present congenitally. Management of CH ideally is through surgical resection or sclerotherapy. A more recent management option is an antiproliferative agent: Sirolimus.9, 12, 13 Sirolimus (rapamycin) is an mTOR inhibitor that has a less drastic adverse effect profile than the preceding management modalities. It inhibits mTOR, which plays an integral role in several signaling cascades that involve cellular motility, angiogenesis, and cell growth.10, 13 Because mTOR is the final common pathway mediating most vascular tumors, sirolimus is an important target to treat lymphangiomas and hemangiomas.8, 9, 10, 13

Pharmacokinetics associated with sirolimus varies considerably because of its metabolism by cytochrome P450 enzymes, thereby depending on the maturation of these microsomal enzymes in young infants and neonates. Among the CYP450 enzymes, CYP3A4, CYP3A5, and CYP2C8 are the most commonly implicated in sirolimus clearance with 95% of metabolism carried out by CYP3A.

Several recent studies discovered the successful use of sirolimus in treating vascular anomalies.8, 12 Tschauner et al reported a case series of 4 female patients being treated for cystic lymphangioma with sirolimus. Patients' ages ranged between 6 months and 3 years. The maximum reduction in tumor size reported was 75%, whereas the reduction in size of the mass in this patient is 90%. A similar case series was conducted by Lackner et al in which children with Kaposiform hemangioendothelioma (KHE), combined lymphatic-venous malformations, and orbital lymphangioma were treated with sirolimus; end results of sirolimus were reported in terms of clinical improvement rather than by reduction in the size of the lesions.

Rationale for administering sirolimus in this case is extensive size of the cystic hygroma. Sclerotherapy doses depend on the body weight, so it is not possible to completely eradicate a large tumor in an infant. Sclerotherapy targets specific cysts in each session necessitating a minimum of 2 sessions for every cyst. Additionally, the lymphatic malformation in this case was not limited to superficial neck lymphatics, but also involved other soft tissues including the tongue, which is not feasible to be approached by sclerotherapy. Interestingly, the tongue, temples, and cheek showed remarkable reduction in size after sirolimus administration. Although this patient received both sclerotherapy and sirolimus, the sclerotherapy was administered for a reduced course with the considerable reduction in size occurring 10 weeks after the last sclerotherapy, whereas the reduction in size in response to sclerotherapy is anticipated to occur within 6 weeks from administration. We suggest that there is a synergistic effect between sclerotherapy and sirolimus.

Conclusion

Sirolimus is a novel therapy for vascular anomalies. A multidisciplinary approach that involves administering sirolimus and sclerotherapy in addition to a debulking surgery is likely to improve the outcome in patients with cervicofacial lymphatic malformations. However, further studies on larger groups should be conducted to standardize this management approach.