Mesenchymal hamartoma of liver is a benign tumor of infancy characterized by admixture of epithelial structures in a loose connective stroma with fluid accumulation suggestive of lymphangiomatous channels(1). It is a rare tumor of infancy(1-4). Approximately 140 cases have been reported(2). First case was reported in 1903(3).

Case Report

A 4-year-old male child presented with fever and vomiting for the last 15 days and respiratory distress for the last 2 days. There was no history of cough, cyanosis and jaundice. Past history was uneventful. On examination, temperature was 103°F and respiratory rate 64/minute with chest indrawing. Pulse rate was 118/minute and blood pressure was normal. Moderate dehydration was present. Liver was palpable by 6cm below the right subcostal margin in the mid-clavicular line and 3cm in the epigastric region, nontender, smooth surface, firm consistency and rounded borders. Upper border was in the 5th inter- costal space. Spleen was palpable 4 cm below the left subcostal margin, firm in consistency. No other mass was palpable. Chest examination was suggestive of right sided basal pneumonia. Rest of systemic examination was normal. Hemoglobin was 7.5 g/dl, TLC 33,000 per cu mm with polymorphs 84%. BT, CT PTI and platelet count were normal. Serum bilirubin was 0.7 mg/dl, SGPT, was 88 IU/L (normal 0-40 IU/L), serum alkaline phosphatase was 486.1 IU/L (normal 200-770 IU/L), blood urea was 120 mg/dl and serum creatinine was 1.7 mg/dl. Serum electrolytes (sodium, potassium) were normal. Urine culture and blood culture showed growth of E. coli and Staphylococcus epidermidis, respectively. Stool examination was normal. X-ray chest showed decreased translucency in the right lower zone. Ultrasound examination showed enlarged liver with rounded mass (10´9.4 cm) having solid and cystic components in the right lobe of liver and there was no cyst in the kidneys or any other organ. Movements of the right dome of diaphragm were markedly restricted. CT scan showed multiple cysts of varying sizes in the right lobe of liver with enhancement of their walls on contrast. Gall bladder, pancreas, spleen and kidneys were normal (Fig. 1). Ultrasound guided fine needle aspiration cytology (FNAC) from the lesion was not significant. Liver biopsy with Menghinis needle done after two weeks of treatment showed multiple microcysts. Some of the cysts were lined by endothelial cells while the others were enclosed by the hepatocytes (Figs. 2 & 3). The child was given appropriate antibiotics and metronidazole alongwith supportive therapy in the form of oxygen and intravenous fluids. There was improvement in clinical and biochemical profile of the patient within 2 weeks of the treatment.

Fig. 1. CT scan of liver showing multiple cysts of varying sizes in right lobe with enhancement of their walls with contrast.

Fig. 2. Microphotograph of liver biopsy showing multiple microcysts (´ 40).

Fig. 3. Microphotograph of liver biopsy showing cysts lined by endothelial cells (´ 600)

Fig. 4. A hyperdense mass of dv 226-325 HU with the few cystic areas in between, in the right lobe (posterior segment) of the liver.

On follow up, the patient was advised surgical treatment to which he did not comply with. The repeat CT scan of the liver done after 6 months showed a hyperdense mass of dv 226-325 HU with the few cystic areas in between, in the right lobe (posterior segment) of the liver. The mass contained dense and irregular calcification. Rest of the liver showed dv 65-70 HU precontrast and enhancement to dv 87-90 HU post contrast (Fig. 4).

Discussion

Mesenchymal hamartoma of liver is primary benign tumor that occurs exclusively during infancy and childhood although few cases in older age groups have been reported(5). Majority of the cases present at mean age of 16 months, the range being from newborn to 5 years. The origin is mostly from right lobe of the liver(2).

Most of the cases remain asymptomatic while the others are detected incidentally when they present with right upper quadrant mass, respiratory distress, fever and raised right hemidiaphragm(2,4). Liver function tests usually remain within normal limits. The most helpful diagnostic tests are ultrasono-graphy and computerised tomography(4). On CT scan, it presents as a complex mass containing areas of low attenuation separated by solid septae and stroma which enhance with intravenous contrast administration(6).

Benign liver tumors in children may be divided into two major groups: those of epithelial derivation, including simple cysts, focal nodular hyperplasias and adenomas and those of mesenchymal derivation including hamartomas and hemangiomas. Benign me-senchymal tumors of liver are more common than their epithelial counterparts(2). The hamartoma is characterized by marked overgrowth of mesenchymal or connective tissue of varying maturity and marked tendency to cyst formation. The mesenchyme may contain minor remnants of liver cells, duct cells and even portal tissue, the most characteristic feature being overgrowth of connective tissue. The lobular architecture is maintained. The cysts may be without lining or may be lined with flattened cells thought to be mesothelial cells(2,7).

The vascular lesions of mesenchymal origin are hemangioendothelioma and cavernous hemangioma. Hemangio-endothelioma usually presents before six months of age and is more common in females. It may be asympto-matic or presents as hepatomegaly, abdominal mass or high output cardiac failure. Microscopically, tumor is quite vascular consisting of variable sized vascular spaces lined by relatively immature plump endothelial cells. On CT scan, hypodense well defined homogenous masses are seen with calcification in 40% cases. Early peripheral enhancement with gradual central filling is evident. Cavernous hemangioma occurs in all age groups and is often asymptomatic and discovered incidently. It is usually solitary lesion with predilection for right lobe and female population. Pathologically, it is a very vascular lesion and shows multiple dilated blood filled spaces lined by mature flat endothelium and separated by fibrous stroma. On CT scan, it is seen as hypodense to isodense well defined mass. On contrast, early peripheral dense nodular enhancement with later centripetal fill is noted(6).

In contrast, simple non-parasitic cyst is solitary which may be very large with lining of columnar, cuboidal or flattened epithelium. The wall is thin and composed of mature connective tissue(7). Simple cysts may also show calcification(2).

The polycystic liver disease on the other hand is frequently associated with polycystic kidneys in about 50% of the patients(8,9). Frequently, there is cystic disease of other organs including spleen, pancreas, ovaries and lungs. The cysts may be scattered diffusely or restricted to one lobe usually left. Hepatic function is excellent as liver cells are preserved. CT scan is useful in diagnosing the lesion as it does not show enhancement with intravenous contrast. It may remain asymptomatic although portal hypertension is common in infantile variety. Symptomatic patients are usually in the 4th or 5th decade and symptoms are often due to associated polycystic kidneys(9). Histologically, there is greater replacement of hepatic parenchyma in polycystic disease. The cystic areas are related to bile ducts and are lined by columnar or cuboidal epithelium. Outside the epithelium, cyst walls consist of thin layer of collagenous connective tissue(8,9).

The treatment of cystic mesenchymal hamartoma is surgical. There are four surgical options and procedure chosen must be in-dividualized. These include enucleation, mar-supialization of cysts, excision of hamartoma with surrounding rim of normal liver tissue and formal hepatic lobectomy. Excision or marsupialization is recommended in all patients with very low surgical morbidity and mortality(2). This condition has excellent long term prognosis(2,4).

Cystic mesenchymal hamartomas of the liver do not generally calcify(1-5). The cases as reported in the literature underwent surgery

and no follow up reports without surgery are available. No surgery was done in the present case and the differences in the pictures of CT scans done 6 months apart may be due to surgical  non-intervention.

References

1. Srouji MN, Chatten J, Schulman WM, Ziegler MM, Koop EC. Mesenchymal hamartoma of the liver in infants. Cancer 1978; 42: 2484-2489.

2. De Maioribus CA, Lally KP, Kenneth S, Hart H, Hossein M. Mesenchymal hamartomas of the liver. A 35-years Review. Arch Surg 1990; 125: 598-600.

3. Maresch R. A lymphangioma of the liver, Z Heilk. 1903; 4: 39.

4. Ros PR, Goodman ZD, Ishak KG, Dachman AH, Olmsted WW, Hartman DS, et al. Mesenchymal hamartoma of the liver: Radiologic - Pathologic correlation. Radiology 1986; 158: 619-625.

5. Dooley JS, Li AKC, Scheuer PJ, Hobbs KEF, Sherlock S. A giant cystic mesenchymal hamartoma of the liver. Diagnosis, management and study of cyst fluid. Gastroenterology 1983. 85: 958-961.

6. Suri S. Hepatic masses in children. In: Diagnostic Radiology: Pediatric Radiology, New Delhi, 1st edn. Eds. Berry M, Suri S, Chowdhury V. Jaypee Brothers. Medical Publishers (P) limited; 1997; pp 42-51.

7. Johnston PW. Congenital cysts of the liver in infancy and childhood. Amer J Surg 1968; 116: 184-191.

8. Comfort MW, Gray HK, Dahlin DC, Whitesell FB. Polycystic disease of the liver: A study of 24 cases. Gastroenterology 1958; 20: 60- 78.

9. Sherlock S, Dooley J. Cysts and congenital biliary abnormalities. In: Diseases of Liver and Biliary System, 10th edn. Oxford, Blackwell Science. 1997; pp 579-591.