Hepatic Mensenchymal Hamartoma of an Infant

By Hiroshi Ito, Teruaki Kishikawa, Takashi Toda, Masayuki Arai, and Hiroyuki Muro

Toyoake, Japan

�9 An 8-month-old boy was found to have a solitary hepatic mesenchymal hamartoma. Histologically, the lesion appeared as a large island of loose mesenchy- real tissue with few cystic bile ducts and liver cells. Electronmicroscopy showed microvilli on the surface of tumor cells and desmosomes between the cells. Immunohistochemical studies showed that (x-feto- protein was localized in the proliferating liver cells and bile ductal epithelium of this neoplasm. This case is the 17th case of hepatic mesenchymal hamartoma reported in Japan.

INDEX WORDS: Liver neoplasm; hamartoma; (x- fetoprotein: immunohistochemistry.

A CYSTIC or tumorous mesenchymal lesion of the liver was first described as a hepatic

mesenchymal hamartoma by Edmondson. 1 This tumor is relatively rare and only 17 cases have been reported in Japan. 2 Serum o~-fetoprotein (AFP) was measured in seven of these cases and a high level was found in five cases. 2 The site of

Fig. 1. Operative findings. Tumor found beneath the right hepatic lobe,

production of AFP in this tumor has not yet been identified. This paper reports t he pathological electron-microscopic and immunohistochemical features of the tumor in an 8-month-old boy.

CASE REPORT

An apparently healthy 8-month-old boy admitted to Fuji- ta-Gakuen University Hospital because of abdominal disten- sion and an abdominal mass from the age of 7 months. The upper abdominal mass was detected on routine examination on admission to hospital. Physical examination revealed a distended abdomen with venous dilatation and a smooth, hard, non-tender mass between the right hypochondrium and lower abdomen.

Significant labolatory data were as follows: RBC, 383 x 104; hemoglobin, 9.7 g/dL; hematocrit, 25%; WBC, 14,100; GOT, 3t mlU/mL; LDH, 171 mlU/mL; serum a-fetopro- tein, 3,200 ng/mL.

Technetium-99m phytate scans of the liver demonstrated a huge, well-defined mass beneath the right hepatic lobe. The 99mTc uptake in the tumor tissue was less than that in normal liver tissue.

Abdominal angiography was performed through a right femoral artery. The right hepatic artery was markedly enlarged and elongated in association with extension of the tumor below the right hepatic lobe. Angiographically, the vascular shadow in the tumor was the shape of a weeping willow, showing hypervascularity and slight irregularity. From angiographic findings, the tumor was suspected to be a massive hepatoblastoma or another type of benign hepatic tumor.

At operation, a huge pedunculated tumor was found beneath the right hepatic lobe. The surface of the tumor was slightly uneven and dark reddish in color with proliferation of blood vessels. Right hepatic lobectomy and cholecystectomy were performed because the tumor was suspected to be a hepatoblastoma. The tumor weighed 1320 g and measured 16.5 x 14 x 8 cm. The cut surface of the tumor showed a well-defined border and yellowish-white nodular tissue with brown stripes but no gross cysts (Fig. 1). Light microscopy showed that the neoplasm consisted of a few cystic bile ducts, much proliferative hepatocellular tissue and large islands of loose mesenchymal tissue (Fig. 2).

Ultrastruacturally, the luminal surface of epithelial cells of

From the Department of Surgery, Fujita-Gakuen Univer- sity, School of Medicine, Toyoake, the Department of Pathology, Fufita-Gakuen University, School of Hygiene, Toyoake, and the Department of Pathology, Hamamatsu Medical School, Hamamatsu.

Address reprint requests to Hiroshi 1to, MD, Department of Surgery, Fujita-Gakuen University, School of Medicine, 1-98, Kutsukake-cho, Toyoake, 470-1 I, Japan.

�9 1984 by Grune & Stratton, Inc. 0022-3468/84/1903-0022501.00/0

Journal of Pediatric Surgery, Vol. 19, No. 3 (June), 1984 315

316 ITO ET AL

Fig. 2. Proliferation of bile duct like glands, hepato- cytes and myxomatous mesenchyme (x 200, H.E.).

the bile-duct-like glands were seen to have numerous pleo- morphic microvilli. The cells had edematous cytoplasm with few cytoplasmic organelles and a round or lobulate nucleus. The plasma membranes between cells were tightly apposed and connected by desmosomes (Fig. 3). The glands around the bile-duct were filled with amorphous mucinous material and a few scattered fibroblasts. Hepatic parenchymal cells of surrounding the tumor did not show any remarkable changes due to tumor development.

Accordingly, this neoplasm was diagnosed as a mesenchy- mal hamartoma. The location of AFP was determined immu- nohistochemically with peroxidase antiperoxidase complex IgG (PAP IgG). 3 The antigen of AFP appeared as brown granules in the cytoplasm of proliferated liver cells and the cystic bile ductal epithelium of this neoplasm (Fig. 4).

DISCUSSION

Mesenchymal hamartoma of the liver is a rare benign tumor of childhood which was first

Fig. 3. Luminal surface showing microvilli. Note des- mosomes between cells (x 6000, E.M.).

reported by Maresh in 1903. 4 In 1956, Edmond- son distinguished mesenchymal hamartomas from other cysts and tumor-like lesions of the liver.t Most cases of this tumor are found during the first two years of life: of the 17 cases reported in Japan, 13 were found in children of under 2 years old. 2 Most patients with these tumors are admitted to the hospital complaining of rapid increase in abdominal girth asymptomatically. The rapid increase in size has been attributed to enlargement of cystic components of the tumor, 5 but the rapid increase in abdominal girtla is probably also due to the rapid growth of this solid tumor.

Values in liver function tests on previous cases were mainly within normal limits, but this case showed slightly increased GOT and LDH levels.

HEPATIC MENSENCHYMAL HAMARTOMA OF AN INFANT 317

Fig. 4. AFP shown as brown granules in the cytoplasm of hepatocytes and bile ductal epithelium (• left side, • right side. PAP IgG).

S e r u m A F P has been measured in seven of 17 Japanese cases repor ted and found to be high in five cases. The range of repor ted A F P levels was 3200 to 6000 n g / m L . 2 Af t e r resection of the

tumors , the serum A F P level rap id ly decreased to normal in all cases. The serum A F P of the present case was 2 0 n g / m L at 4 weeks postopera- tively.

The locat ion of A F P in hepat ic mesenchymal h a m a r t o m a s has not previously been examined. In the present s tudy the ant igen of A F P was de tec ted by P A P l g G in the hepatocytes and d i la ted bile duct ep i the l ium within loose myxo- matous s t roma, suggest ing tha t A F P is p roduced by prol i fera t ing hepatocytes .

The surgical p rocedure of lobectomy or enu- cleat ion of the t umor is usual ly employed because the tumor grows rapidly. Af te r estab- l i shment of a definite diagnosis of mesenchymal hamar toma , enucleat ion of the tumor is sug- gested to be preferab le to lobectomy because this tumor is a benign liver tumor and shows no r e c u r r e n c e a f t e r su rge ry . 6"7 Howeve r r igh t hepat ic lobectomy was per formed in this case because the diagnosis of hepa tob las toma was not f i rmly ruled out dur ing operat ion.

REFERENCES

1. Edmondson HA: Differential diagnosis of tumors and tumor-like lesions of liver in infancy and childhood. AMA J Dis Child 91:168-186, 1956

2. Ito H, Toda T, Kishikawa T, et ah A case of mesenchy- mal hamartoma of the liver with a review of the reported cases in Japan. J Jpn Soc Pediatr Surg 15:997-1004, 1979

3. Sternberger LA, Hardy Jr PH, Cuculis J J: The unla- beled antibody enzyme method of immunohistochemistry. J Histochem Cytochem 18:215-333, 1970

4. Maresh R: Uber ein Lymphangiom der Leber. Ztschr Heilk 24:39-50, 1903

5. Abdul Razek MS, Marroum MCF, Nassar VH, et al: Cystic mesenchymal hamartoma of the liver in infants and children. Leb Med J 26:673-682, 1973

6. Katzman HE: Mesenchymal hamartoma of the liver. J Pediatr Surg. 7:71, 1972

7. lshida M, Tsuchida Y, Saito S: Mesenchymal hamar- toma of the liver. Ann Surg 164:175-182, 1966