Ciliated Hepatic Foregut Cyst: Two Case Reports in Children and Review of the Literature

Ciliated hepatic foregut cyst (CHFC) is a rare lesion which originates from detached hepatic diverticulum or from detachment and migration of buds from the esophageal and bronchial regions of the foregut which subsequently get entrapped by the liver during the early embryonic development of the foregut. CHFCs are mostly seen in adults and are rarely reported in children, with only about 10 cases reported in this age group. Hereby, we present two cases of CHFC in two 3.5-year-old boys; one of them had cystic lesion at medial segment of left lobe of liver (common site), and in the other one it was located at right lobe of liver (less common site). Histologically, both cysts had four layers composed of inner ciliated, pseudostratified, columnar epithelium; subepithelial connective tissue; smooth muscle layer; and an outer fibrous layer.


Case 1
A 3.5-year-old boy presented with right upper quadrant abdominal pain. At the ninth month of gestation, a liver cyst was detected by US (no photographs were available). No further investigation was done after birth. Physical examination was normal. Laboratory tests showed mild microcytic anemia (Hb: 10.7 gr/dL, normal range: 11-14; MCV: 71.9 FL, normal range: 73-85); the other tests, including liver function tests, were within normal limits. Ultrasonography and CT showed a simple 3.7 × 2.8 cm subcapsular liver cyst in median

Case 2
A 3.5-year-old boy was referred to the hospital with constipation. Physical examination was normal. A hepatic cyst was detected by US. Hematologic test showed mild normocytic anemia (Hb: 10.9 gr/dL, normal range: 11-14; MCV: 81 FL, normal range: 73-85). Serum electrolytes and liver function test were within normal limits. Ultrasonography showed a heterogeneous lesion, measuring 3.6 × 3.2 cm in right lobe of liver ( Figure 1(b)), and CT showed a hypodense cystic lesion without enhancement. The cyst was resected with clinical and radiological diagnosis of hydatid cyst and the specimen consisted of a previously opened cyst with rough brown external and internal surfaces, measuring 3.5 × 2.5 cm in diameter and up to 0.5 cm in wall thickness. At histological examination, both cysts had four typical layers of ciliated hepatic foregut cyst, composed of inner ciliated, pseudostratified, columnar epithelium; subepithelial connective tissue; smooth muscle layer; and an outer fibrous layer (Figures 2(a) and 2(b)). Foci of squamous metaplasia without atypia were detected in case 2. The fibrous layers are stained green with Masson trichrome stain (Figure 2(c)). Postoperation course was uneventful in both patients.

Discussion
The incidence of hepatic cysts is approximately 5% in general population; they are classified into parasitic and nonparasitic cysts. One of the uncommon types of liver cyst is CHFC, which arises from the embryonic foregut. It is believed that it originates from a detached hepatic diverticulum or  [20]. Because CHFCs are usually asymptomatic, it is difficult to determine their prevalence. They are usually found in the medial segment of the left lobe beneath the hepatic capsule, but can rarely be found in right lobe [4-7, 9, 13, 14, 19]. One of our cases was located in medial segment of left lobe and the other one was in right lobe. These lesions are extremely rare in children and only 10 cases have been reported (Table 1) [1,[4][5][6][12][13][14][15]. In pediatric population, including this report, five out of 12 cases (41.7%) were diagnosed antenatally and seven (58.3%) were detected postnatally. Both sexes were equally affected. Seventy-five percent of cases (9 patients) were diagnosed before age 5 (including antenatally diagnosed cases) and the remaining 25% (3 cases) were detected between the age 10 and 14 years. Nine patients (75%) were asymptomatic and 25% had symptoms related to the cyst. The maximum size of the cyst was between 0.6 and 11 cm. One of our cases was detected at prenatal sonography and was asymptomatic until 3.5 years of age; the second one had no symptoms related to his hepatic cyst. Both of our cases were male and the cysts were 3.5 and 3.7 cm in maximum diameter.
The clinical course is usually benign; however, malignant transformation to squamous cell carcinoma with aggressive behavior has been reported in 3% of cases, all of which happened in adults between 21 and 51 years of age, supporting the idea of excision of the cyst when discovered in adults, and careful clinical followup of the patients [1,9,[16][17][18]. In children, some recommend that the cyst removal should be performed after one year of age in asymptomatic cases, due to high risk of hepatic procedures [4]. However, one may argue that in asymptomatic children, it would be wise to monitor clinically and do the surgery when it is necessary. Many cases can be removed laparoscopically [19,22].
Since hydatid cyst is endemic in our country, it is usually at the top of the differential diagnoses list for a liver cyst, such as case 2. Inclusion of CHFC in the differential diagnosis and performance of serological tests to exclude hydatid cyst could make laparoscopic removal more likely with less postoperative complications. We have presented two cases of CHFC in 3.5-year-old boys due to extreme rarity of this lesion in children. CHFC in children is not previously reported from Iran.