^{Sinus pericranii}

Fernando Heredia MD, Hector Figueroa MD.

Departamento de Exploración Fetal, Servicio de Ginecología y Obstetricia, Hospital Regional, Concepción, Chile. Departamento de Ginecología y Obstetricia, Facultad de Medicina, Universidad de Concepción, Chile.

Synonyms: Epicranial sinus, subepicranial varix.

Definition: Sinus pericranii is a rare anomaly, characterized by a blood-filled nodule of the scalp that is in communication with an intracranial dural sinus (usually the superior sagittal sinus)[1],[2],[3].

Prevalence: Unknown. Up to 1994 approximately 100 cases had been reported in medical literature[4] with les than 10 cases being congenital[5],[6],[7].

Etiology: Unknown.

Pathogenesis: Congenital, acquired or traumatic[8],[9].

 Associations: Craniosynostosis[10] and Crouzon disease[11] in early childhood, and multiple angiomatosis in adults[12].

Differential diagnosis: Cavernous angioma of the scalp. Other soft tissue solid scalp tumors.

Case report:

A 19-year-old primigravida was referred at 38 weeks because of moderate preeclampsia. Obstetric history was otherwise unremarkable. Fetal ultrasound showed a solid hyperechogenic mass of the posterior skull. It seemed to be compressed to the uterine wall.

A C-section was performed and a healthy 3.450 kg boy was delivered. Pediatric examination noted a fluctuating non-pulsatile reddish-colored mass on the occipital area, slightly to the right of the midline. It measured 5 x 5 cm, and surprisingly enlarged when the baby was crying.

Neonatal contrasted-MRI showed communication between the tumor and the transverse sinus, and thus sinus pericranii was diagnosed.

Complete resection of the lesion was successfully performed at 6 months of age.

Discussion:

As sinus pericranii usually presents in adults, little is known about events leading to its congenital presentation. In fact, to our knowledge, these are the first prenatal ultrasound images of this anomaly.

Sinus pericranii is usually located in the midline and often in the frontal region[13], but parietal, temporo-occipital[14] and mastoid bone[15] locations have also been described.

This diagnosis is difficult to make clinically, because the skin manifestations are highly variable and may resemble other disorders of the scalp and cranium. They can even present as dilated scalp veins (and not a patent tumor!!!), due to altered venous drainage of sagittal sinus blood. Concomitant symptoms are rare, although some patients complain of headache, nausea and vertigo[16]. A clue for diagnosis is the acute distention of the mass with the Valsalva maneuver and its complete disappearing when the patient is in sitting position[17]. Spontaneous regression has occasionally been reported[18].

Definitive diagnosis can be made through angiography and percutaneous sinography but contrasted MRI is the gold standard[19],[20].

Complications include: hemorrhage, infection, and air embolism.

Management: Surgical removal is recommended and is usually easy. When the sinus is small, the flow within the mass is slow there is no significant communication with the cerebral veins, endovascular sclerosis may be advocated.

[13] Desai K, Bhayani R, Goel A, Muzumdar D. Sinus pericranii in the frontal region: a case report. Neurol India  2001 Sep;49(3):305-7

[14] Marras C, McEvoy AW, Grieve JP, Jager HR, Kitchen ND, Villani RM. Giant temporo-occipital sinus pericranii. A case report. J Neurosurg Sci  2001 Jun;45(2):103-9

[15] Witrak BJ, Davis PC, Hoffman JC Jr. Sinus pericranii. A case report. Pediatr Radiol  1986;16(1):55-6

[16] Madsen JR, Robertson RL, Bartlett R. Surgical management of cutis aplasia with high-flow sinus pericranii. Pediatr Neurosurg  1998 Feb;28(2):79-83

[17] Asano K, Sobata E, Kubo O. Subepicranial varix mimicking sinus pericranii: usefulness of three-dimensional computed tomography angiography and bone window computed tomography--case report. Neurol Med Chir (Tokyo)  2000 Sep;40(9):467-71

[18] Hayakawa I, Fujiwara K, Sasaki A, Hirata T, Yanagibashi K, Tsuchida T. Spontaneous regression of sinus pericranii--report of a caseNo Shinkei Geka  1978 Jan;6(1):91-5

[19] Higuchi M, Fujimoto Y, Ikeda H, Kato A. Sinus pericranii: neuroradiologic findings and clinical management. Pediatr Neurosurg  1997 Dec;27(6):325-8