HEPATIC HEMANGIOMA IN PREGNANCY

Hemangiomas are the most common benign liver neoplasm, consisting of vascular channels lined

by a single layer of endothelium and separated fibrous stroma, occurring in approximately 2% to 7% of general population[ 1,4].  These arise from the endothelial cells that line blood vessel walls. The etiology of these lesions is not well understood, although they are most likely congenital in origin, and are detected most frequently in middle-aged women, with a 5:1 female to male ratio [2].

Because the lesions are relatively common it is very useful to recognize typical and atypical sonographic appearances to avoid misdiagnosis or confusion.

Sonography has become a first-line diagnostic tool; it is widely available and inexpensive.  This fact presents sonography the opportunity to initially identify many rare abnormalities [3].It is estimated that approximately 67% to 79% of hemangiomas are hyperechoic, and of these, 58% to 73% are homogeneous. Hemangiomas are characterized by very slow blood flow that will no routinely be detected by either color or duplex Doppler. Occasional lesion may show a low-range to midrange kHz shift both peripheral and central blood vessels. Serial examinations can be used to monitor any increase in size of the hemangioma over time [6].

The characteristics of an atypical hemangioma are as follow: greater than 4 cm, heterogeneous, mixed echogenicity, limited posterior enhancement, and the possibility of increased blood flow. [1] Atypical hemangiomas, also known as giant hemangiomas, are considered a rare presentation of an otherwise common incidental finding [3]. Giant hemangiomas may create a clinical picture that is very different from the typical asymptomatic hemangioma [5].

Many hemangiomas are discovered incidentally during the course of CT imaging for other reasons. The finding of globular peripheral enhancement during routine dynamic bolus CT is a strong indicator that the lesion is a cavernous hemangioma. Contrast enhancement progresses centripetally, beginning peripherally, with late hyperdensity in the central portion of the tumor. Upon complete isodense opacification of these lesion on delayed scans up to 60 minutes after contrast administration, between 55% and 79% of hepatic hemangiomas are specifically diagnosed [6].

Magnetic resonance imaging (MRI) is more accurate than CT in diagnosing hemangiomas.  Hemangiomas are usually of low signal on T1-weighed images, becoming increasingly bright and of very high signal intensity on T2-weighted images, regardless of field strength. The characteristic pattern of enhancement is similar to that of dynamic CT, peripheral hyperintense nodules, progressive centripetal enhancement, and persistent homogeneous enhancement [4, 6].

Technetium-99m red blood cell scintigraphy, is another diagnostic tool that can be used it, where you expect to see on delayed phases a defect in the early phases that shows prolonged and persistent filling-in [7].

Because most hemangiomas are an incidental finding, are asymptomatic, and have no known risk of malignancy, they are usually managed by periodic observation to ensure stability [3].