Mesenchymal Hamartoma
of the Liver
A 35-Year Review Christopher A. DeMaioribus, MD; Kevin P. Lally, MD; Kenneth Sim, MD; Hart Isaacs, MD; G. Hossein Mahour, MD \s=b\ Mesenchymal hamartoma of the liver occurs almost exclusively in infancy and childhood, with approximately 140 total cases reported. We report the experience with 18 patients at the Childrens Hospital of Los Angeles (Calif) during the past 35 years. The charts of all patients with mesenchymal hamartoma were retrospectively reviewed. The mean age at presentation was 16 months. Thirteen patients were symptomatic, presenting with increasing abdominal distention. Physical examination revealed an abdominal mass or hepatomegaly. Ultrasonography and computed tomography were the most useful diagnostic tests. Fourteen patients underwent resection; 9 underwent hepatic resection and 5 underwent excision of the tumor only. One patient had marsupialization, 1 underwent a biopsy only, and 2
died of unrelated causes and the hamartoma was found incidentally at autopsy. In all instances, a large cystic mass with well\x=req-\ demarcated margins was found. Three patients were unavailable for follow-up and 13 patients were alive and well 1 month to 24 years (mean, 5 years) after diagnosis. Recurrence or malignant transformation was not noted. A presumptive diagnosis can be made preoperatively by normal laboratory values and a combination of ultrasonography and computed tomography. We recommend excision of the tumor in all patients once the diagnosis is made, with the expectation of complete recovery.
(Arch Surg. 1990;125:598-600)
Mesenchymal benign
hamartoma of the liver is an uncommon lesion seen almost exclusively in children youn¬ ger than 2 years. It is the second most common benign liver tumor seen in children, with approximately 140 total cases reported. A recent series of patients seen at our institution prompted us to review our experience with mesenchymal hamartoma. We present 18 patients with mesenchymal ha¬ martoma of the liver seen at the Childrens Hospital of Los
Angeles (Calif) during a 35-year period.
PATIENTS AND METHODS The records of all patients with mesenchymal hamartoma of the liver seen at the Childrens Hospital of Los Angeles during the years
Accepted for publication October 16,1989. From the Department of Surgery, Wilford Hall US Air Force Medical Center, Lackland Air Force Base, Tex (Drs DeMaioribus and Lally), and the Divisions of Pediatric Surgery (Drs Sim and Mahour) and Pathology (Dr Isaacs), Childrens Hospital of Los Angeles and the University of Southern California School of Medicine, Los Angeles. The opinions expressed herein reflect those of the authors and are not necessarily those of the US Air Force or the Department of Defense. Reprints requests to the Department of Surgery/SGHSG, Wilford Hall, USAF Medical Center, Lackland AFB, TX 78236 (Dr Lally).
1952 to 1986 were retrospectively reviewed. During approximately the same period, a total of 48 patients with benign liver tumors and 46 patients with malignant liver tumors were seen. The records were examined for clinical histories, laboratory evaluations, roentgeno¬ graphic studies, surgical descriptions, gross and microscopic patho¬ logic reports, and outcomes. Outpatient records were used for longterm follow-up information. All pathologic slides were reviewed to confirm the original diagnosis.
RESULTS There were 9 boys and 9 girls. Their ages at diagnosis ranged from newborn to 5 years, with a mean of 16 months. The presenting symptom in each of the 13 symptomatic pa¬ tients was progressive abdominal distention. Among the chil¬ dren who were asymptomatic, 2 had a liver mass discovered incidentally at autopsy after death from other causes. One presented with an abdominal mass found on a routine physical examination, and 1 was referred to the Childrens Hospital of Los Angeles after marsupialization of a mesenchymal hamar¬ toma elsewhere. One patient's presenting symptoms were not known. Associated symptoms were poor appetite in 3 patients and respiratory distress in 1 patient secondary to impaired diaphragmatic excursion from the underlying he¬
patic mass. Physical examinations revealed a right upper quadrant mass in nine patients, a left upper quadrant mass in one patient, and hepatomegaly alone in the remaining eight pa¬ tients. In all patients, the mass or the enlarged liver was nontender. Dilated superficial abdominal veins were ob¬ served in four patients, and two patients were cachectic, as shown below:
Symptoms and Findings in 18 Patients Total symptomatic patients
Progressive abdominal distention Poor appetite Respiratory distress Physical findings Right upper quadrant mass Hepatomegaly Left upper quadrant mass
No. (%) of Patients 13 (72)
13 (72)
13(72)
3 (16) 9 (50) 8 (44) 1 (5.5)
Laboratory evaluation was not helpful in making the diag¬ nosis. Ten patients underwent liver function tests, including a determination of total bilirubin values, direct-reacting biliru¬ bin values, alkaline phosphatase levels, lactic dehydrogenase levels, and aspartate aminotransferase levels. In all but three
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
patients, these results were within normal limits. One patient with evidence of associated congenital cardiac disease had indirect hyperbilirubinemia. Another patient had an isolated elevation of alkaline phosphatase level. Various roentgenographic studies were used in the evalua¬ tion of these patients. Plain films of the abdomen were of little value, showing only the presence of a soft-tissue mass in the abdomen. Contrast studies, such as intravenous pyelography (five patients), upper gastrointestinal tract series (five pa¬ tients), and barium enema (three patients) were not useful. They showed displacement of adjacent abdominal viscera by the large hepatic mass. In no patient did the hamartoma cause obstruction of other abdominal organs. Radionuclide liver scans were done in four patients, showing an intrahepatic mass with decreased uptake. Arteriography was performed in six patients. The liver lesion appeared as a hypovascular mass. There were no pathologic vessels within the lesion. The most helpful diagnostic tests were ultrasonography and com¬ puted tomography. Ultrasound examination in seven patients
revealed a characteristic lobular mass with internal septations and central cystic areas. The computed tomographic scan, performed on three of the most recent patients, showed an intrahepatic cystic mass with smooth margins and a septated central cystic area (Fig 1). Fourteen patients underwent exploratory laparotomy with resection of the neoplasm. Nine of these patients had hepatic lobectomy, while 5 had simple excision of the mass. One patient underwent a biopsy and marsupialization of the cystic lesion elsewhere after an attempted resection was aborted because of excessive blood loss. One patient with associated congenital heart disease underwent a needle biopsy of the lesion only. There was no operative mortality. These results are shown below: No. (%) of Patients Operation
Hepatic resection Lobectomy Partial left lobectomy Trisegmentectomy Simple excision Marsupialization Needle biopsy
9 (50) 5 (28)
2(11) 2(11) 5 (28) 1 (5.5) 1 (5.5)
Grossly, the lesions appeared as very large, solitary, rounded or irregular masses, measuring up to 22 16 x 8 cm and weighing as much as 1898 g. They were sharply demarcat¬ ed from adjacent liver parenchyma, but a definite capsule was present in only 1 patient. The mass was within or protruding from the right hepatic lobe in 13 patients and from the left hepatic lobe in 4 patients. In 1 patient the location could not be determined by a review of the chart. Multiple cysts were present on the surface of the speci¬ mens. On section, the cysts had a glistening lining and inter¬ nal trabeculations and were filled with a yellowish fluid or mucoid material. In one patient the cystic areas were filled with clotted and unclotted blood. White fibrous-appearing connective tissue separated the cysts. Some areas of the lesion were composed of a myxoid stroma and small islands of liver parenchyma. Microscopic examination revealed multiple large cystic spaces lined with a flattened or cuboidal epithelium, or, in some cases, there was no lining (Fig 2). The cysts appeared to represent either dilated bile ducts or degenerated mesenchy¬ mal spaces. The cysts were surrounded by dense fibrous connective tissue septae and interspersed in a loose myxoid stroma
Fig 1.—Mesenchymal hamartoma originating in the right hepatic lobe.
containing prominent ground substance, mesenchy¬
mal cells, blood vessels, and a proliferation of bile ducts. Within the interstitium and between the cysts were islands of compressed liver tissue. One specimen snowed multiple foci of extramedullary hematopoiesis. Within this matrix were
Fig 2.—Microscopic section revealing cysts of various sizes and shapes lined by the endothelium and the cuboidal bile duct epithelium surrounded by a pale connective tissue ("mesenchymal") stroma (he¬ matoxylin-eosin, original magnification 100). islands of normal or compressed liver tissue. Routine electron
microscopy was not performed. Follow-up information was available in 13 patients. The period of follow-up ranged from 1 month to 24 years (mean, 5 years). There were no recurrences or malignant transforma¬ tions. All patients were doing well and were free of symptoms.
COMMENT
Benign liver tumors in children may be divided into two major groups: those of epithelial derivation, including simple cysts, focal nodular hyperplasia, and adenomas; and those of mesenchymal derivation, including cavernous hemangiomas, capillary hemangioma (hemangioendotheliomas), and hamartomas.13 Benign mesenchymal tumors of the liver are more common than their epithelial counterparts.3 Mesenchymal hamartoma of the liver is considered to be an uncommon developmental anomaly seen almost exclusively in children younger than 2 years,4 although presentation in older children
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
has been
reported.5"8 It is generally regarded as the second
benign liver lesion in children, following hemangiomas.9 Mesenchymal hamartoma of the liver bears no relationship to cystadenoma with mesenchymal stroma of the liver and bile ducts. Cystadenoma with mesenchymal stroma is a premalignant lesion composed of cysts lined with colum¬ nar mucous-secreting epithelium and a cellular stroma resem¬ bling primitive mesenchyme. It is seen almost exclusively in female patients, most commonly in the fifth decade of life.10 The exact pathogenesis of mesenchymal hamartoma is not clear, but the prevalent theory is that it represents aberrant development of primitive mesenchyme in the portal tracts, most likely from bile ducts.11 This theory is supported by the predominance of proliferating bile ducts seen histologically. It is thought that the anomaly occurs late in embryogenesis, most
common
the liver maintains its lobular architecture and connection to the biliary tree. The lesion is thought to spread along portal tracts, entrapping islands of liver tissue as it grows. " Most investigators believe that the solid portion of the lesion is developed by the peripartum period. Stocker and Ishak4 postulated that the rapid enlargement of the tumor, manifested by increasing abdominal distention, is caused by cystic degeneration of the mesenchyme with secondary fluid accumulation within cysts, obstruction and dilatation of lym¬ phatics, or both. By far, the most common presenting symptom in patients with mesenchymal hamartoma of the liver is abdominal dis¬ tention, with or without the presence of a discrete mass. Associated symptoms are rare, the most significant being respiratory embarrassment from interference with normal ventilatory mechanics by a large hepatic mass. Cachexia may be present. Roentgenographic evaluation will usually establish the di¬ agnosis. Plain films of the abdomen and gastrointestinal tract contrast studies are not useful. Ultrasonography is the most informative examination, and we believe it should be used as the primary screening test for children with increasing ab¬ dominal distention or a hepatic mass. Most hepatic masses in the pediatrie age group are solid. The differential diagnosis of a cystic lesion is limited and includes mesenchymal hamar¬ toma, malignant mesenchymoma with a cystic component, and cystic hepatoblastoma (rare).1213 Malignant mesenchyas
of the liver (also called undifferentiated sarcoma of the liver) is mainly seen in an older age group. In a review of 31 moma
cases of patients referred to the Armed Forces Institute of Pathology, Washington, DC, 51.6% occurred in children aged 6 to 10 years. Only 16% were seen in children younger than 5 years.14 Clinically, most patients present with abdominal pain, in contradistinction to mesenchymal hamartoma of the liver.15 Teratomas and simple cysts are also possibilities, but these will usually show calcifications on plain films or ultrasonog¬ raphy. Computed tomography supports ultrasonography by showing the extent of the hepatic mass and its relationship to adjacent structures.13,16 Arteriograms may be useful but are not necessary. Once the diagnosis is made, removal of the lz
lesion is recommended. In our experience, there was no oper¬ ative mortality. There are four surgical options, and the procedure chosen must be individualized. If the tumor can easily be dissected from the surrounding tissue, enucleation is possible.5,17,18 This approach minimizes loss of normal liver tissue and decreases blood loss. With especially large lesions or in selected patients marsupialization of the cysts into the peritoneal cavity may be employed, although we have no experience with this tech¬ nique.19 The child in our series who underwent marsupializa¬ tion was alive and well 1 year after surgery, but was subse¬ quently unavailable for follow-up. Our preference has been excision of the hamartoma with a surrounding rim of normal liver tissue. While malignant mesenchymoma usually appears in an older age group and has a different clinical presentation, some crossover is possible. Excision is a safe procedure if it provides a clear margin. The final option is a formal hepatic lobectomy, which may be performed safely in children and was used in a number of our patients.19 Mesenchymal hamar¬ toma, however, is a benign lesion and we feel that an overly aggressive surgical approach is not usually justified. Diagnosis of mesenchymal hamartoma of the liver should be suspected in children under the age of 2 years with a suggestive medical history. This is confirmed by abdominal ultrasonography and computed tomography. Excision or marsupialization is recommended in all patients, with the expectation of very low surgical morbidity and mortality and an excellent long-term prognosis.
References 1. Edmonson HA, Peters RL. Tumors of the liver: pathologic features. Semin Roentgenol. 1983;18:75-83. 2. Ehren H, Mahour GH, Isaacs H. Benign liver tumors in infancy and childhood. Am JSurg. 1983;145:325-329. 3. Smith WL, Franken EA, Mitros FA. Liver tumors in children. Semin
Roentgenol. 1983;18:136-148. 4. Stocker JT, Ishak KG. Mesenchymal hamartoma of the liver: report of 30
and a review of the literature. Pediatr Pathol. 1983;1:245-267. 5. Grases PF, Matos-Villalobos M, Romero F, Lecuna-Torres V. Mesenchymal hamartoma of the liver. Gastroenterology. 1979;76:1466-1469. 6. Holmin T, Kullendorf CM. Diagnostic aids for benign tumors ofthe liver in children. Acta Paediatr Scand. 1981;70:755-757. 7. Salisbury JR, Darby AJ, Pormann BC. Mesenchymal hamartoma of the liver: report of an unusual case. Postgrad Med J. 1986;62:752-760. 8. Shah JP, Goldsmith HS, Huros AG. Hamartomas of the liver. Surgery. cases
1970;68:778-782. 9. Ein SH, Stephens CA. Benign liver tumors and cysts in childhood. J Pediatr Surg. 1974;9:847-851. 10. Wheeler DA, Edmonson HA. Cystadenoma with mesenchymal stroma (CMS) in the liver and bile ducts. Cancer. 1985;56:1434-1445. 11. Dehner LP, Ewing SL, Sumner HW. Infantile mesenchymal hamartoma
Histologic and ultrastructural observations. Arch Pathol. 1975;99:379-381. 12. Rosenbaum DM, Mindell HJ. Ultrasonographic findings in mesenchymal hamartoma of the liver. Radiology. 1980;138:425-427. 13. Stanley RJ, Dehner LP, Hesker AE. Primary malignant mesenchymal tumors (mesenchymoma) of the liver in childhood: an angiographic-pathologic study of three cases. Cancer. 1973;32:973-984. 14. Stocker JT, Ishak KG. Undifferentiated (embryonal) sarcoma of the liver. Cancer. 1978;42:336-348. 15. Newman KD, Schisgall R, Reaman G, Guzzetta PC. Malignant mesenchymoma or the liver in children. J Pediatr Surg. 1989;24:781-783. 16. Ros PR, Goodman ZD, Ishak KG, et al. Mesenchymal hamartoma of the liver: radiologic-pathologic correlation. Radiology. 1986;158:619-623. 17. Ito H, Kishiwaka TT, Toda T, Arai M, Muro H. Hepatic mesenchymal hamartoma of an infant. J Pediatr Surg. 1984;19:315-317. 18. Raffensberger JG, Gonzalez-Crussi F, Skeehan T. Mesenchymal hamartoma of the liver. J Pediatr Surg. 1983;18:585-587. 19. Randolph JG, Altman RP, Arensman RM, Matlack ME, Leikin SL. Liver resection in children with hepatic neoplasms. Ann Surg. 1978;187:599\x=req-\ of the liver.
605.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
of the Liver
A 35-Year Review Christopher A. DeMaioribus, MD; Kevin P. Lally, MD; Kenneth Sim, MD; Hart Isaacs, MD; G. Hossein Mahour, MD \s=b\ Mesenchymal hamartoma of the liver occurs almost exclusively in infancy and childhood, with approximately 140 total cases reported. We report the experience with 18 patients at the Childrens Hospital of Los Angeles (Calif) during the past 35 years. The charts of all patients with mesenchymal hamartoma were retrospectively reviewed. The mean age at presentation was 16 months. Thirteen patients were symptomatic, presenting with increasing abdominal distention. Physical examination revealed an abdominal mass or hepatomegaly. Ultrasonography and computed tomography were the most useful diagnostic tests. Fourteen patients underwent resection; 9 underwent hepatic resection and 5 underwent excision of the tumor only. One patient had marsupialization, 1 underwent a biopsy only, and 2
died of unrelated causes and the hamartoma was found incidentally at autopsy. In all instances, a large cystic mass with well\x=req-\ demarcated margins was found. Three patients were unavailable for follow-up and 13 patients were alive and well 1 month to 24 years (mean, 5 years) after diagnosis. Recurrence or malignant transformation was not noted. A presumptive diagnosis can be made preoperatively by normal laboratory values and a combination of ultrasonography and computed tomography. We recommend excision of the tumor in all patients once the diagnosis is made, with the expectation of complete recovery.
(Arch Surg. 1990;125:598-600)
Mesenchymal benign
hamartoma of the liver is an uncommon lesion seen almost exclusively in children youn¬ ger than 2 years. It is the second most common benign liver tumor seen in children, with approximately 140 total cases reported. A recent series of patients seen at our institution prompted us to review our experience with mesenchymal hamartoma. We present 18 patients with mesenchymal ha¬ martoma of the liver seen at the Childrens Hospital of Los
Angeles (Calif) during a 35-year period.
PATIENTS AND METHODS The records of all patients with mesenchymal hamartoma of the liver seen at the Childrens Hospital of Los Angeles during the years
Accepted for publication October 16,1989. From the Department of Surgery, Wilford Hall US Air Force Medical Center, Lackland Air Force Base, Tex (Drs DeMaioribus and Lally), and the Divisions of Pediatric Surgery (Drs Sim and Mahour) and Pathology (Dr Isaacs), Childrens Hospital of Los Angeles and the University of Southern California School of Medicine, Los Angeles. The opinions expressed herein reflect those of the authors and are not necessarily those of the US Air Force or the Department of Defense. Reprints requests to the Department of Surgery/SGHSG, Wilford Hall, USAF Medical Center, Lackland AFB, TX 78236 (Dr Lally).
1952 to 1986 were retrospectively reviewed. During approximately the same period, a total of 48 patients with benign liver tumors and 46 patients with malignant liver tumors were seen. The records were examined for clinical histories, laboratory evaluations, roentgeno¬ graphic studies, surgical descriptions, gross and microscopic patho¬ logic reports, and outcomes. Outpatient records were used for longterm follow-up information. All pathologic slides were reviewed to confirm the original diagnosis.
RESULTS There were 9 boys and 9 girls. Their ages at diagnosis ranged from newborn to 5 years, with a mean of 16 months. The presenting symptom in each of the 13 symptomatic pa¬ tients was progressive abdominal distention. Among the chil¬ dren who were asymptomatic, 2 had a liver mass discovered incidentally at autopsy after death from other causes. One presented with an abdominal mass found on a routine physical examination, and 1 was referred to the Childrens Hospital of Los Angeles after marsupialization of a mesenchymal hamar¬ toma elsewhere. One patient's presenting symptoms were not known. Associated symptoms were poor appetite in 3 patients and respiratory distress in 1 patient secondary to impaired diaphragmatic excursion from the underlying he¬
patic mass. Physical examinations revealed a right upper quadrant mass in nine patients, a left upper quadrant mass in one patient, and hepatomegaly alone in the remaining eight pa¬ tients. In all patients, the mass or the enlarged liver was nontender. Dilated superficial abdominal veins were ob¬ served in four patients, and two patients were cachectic, as shown below:
Symptoms and Findings in 18 Patients Total symptomatic patients
Progressive abdominal distention Poor appetite Respiratory distress Physical findings Right upper quadrant mass Hepatomegaly Left upper quadrant mass
No. (%) of Patients 13 (72)
13 (72)
13(72)
3 (16) 9 (50) 8 (44) 1 (5.5)
Laboratory evaluation was not helpful in making the diag¬ nosis. Ten patients underwent liver function tests, including a determination of total bilirubin values, direct-reacting biliru¬ bin values, alkaline phosphatase levels, lactic dehydrogenase levels, and aspartate aminotransferase levels. In all but three
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
patients, these results were within normal limits. One patient with evidence of associated congenital cardiac disease had indirect hyperbilirubinemia. Another patient had an isolated elevation of alkaline phosphatase level. Various roentgenographic studies were used in the evalua¬ tion of these patients. Plain films of the abdomen were of little value, showing only the presence of a soft-tissue mass in the abdomen. Contrast studies, such as intravenous pyelography (five patients), upper gastrointestinal tract series (five pa¬ tients), and barium enema (three patients) were not useful. They showed displacement of adjacent abdominal viscera by the large hepatic mass. In no patient did the hamartoma cause obstruction of other abdominal organs. Radionuclide liver scans were done in four patients, showing an intrahepatic mass with decreased uptake. Arteriography was performed in six patients. The liver lesion appeared as a hypovascular mass. There were no pathologic vessels within the lesion. The most helpful diagnostic tests were ultrasonography and com¬ puted tomography. Ultrasound examination in seven patients
revealed a characteristic lobular mass with internal septations and central cystic areas. The computed tomographic scan, performed on three of the most recent patients, showed an intrahepatic cystic mass with smooth margins and a septated central cystic area (Fig 1). Fourteen patients underwent exploratory laparotomy with resection of the neoplasm. Nine of these patients had hepatic lobectomy, while 5 had simple excision of the mass. One patient underwent a biopsy and marsupialization of the cystic lesion elsewhere after an attempted resection was aborted because of excessive blood loss. One patient with associated congenital heart disease underwent a needle biopsy of the lesion only. There was no operative mortality. These results are shown below: No. (%) of Patients Operation
Hepatic resection Lobectomy Partial left lobectomy Trisegmentectomy Simple excision Marsupialization Needle biopsy
9 (50) 5 (28)
2(11) 2(11) 5 (28) 1 (5.5) 1 (5.5)
Grossly, the lesions appeared as very large, solitary, rounded or irregular masses, measuring up to 22 16 x 8 cm and weighing as much as 1898 g. They were sharply demarcat¬ ed from adjacent liver parenchyma, but a definite capsule was present in only 1 patient. The mass was within or protruding from the right hepatic lobe in 13 patients and from the left hepatic lobe in 4 patients. In 1 patient the location could not be determined by a review of the chart. Multiple cysts were present on the surface of the speci¬ mens. On section, the cysts had a glistening lining and inter¬ nal trabeculations and were filled with a yellowish fluid or mucoid material. In one patient the cystic areas were filled with clotted and unclotted blood. White fibrous-appearing connective tissue separated the cysts. Some areas of the lesion were composed of a myxoid stroma and small islands of liver parenchyma. Microscopic examination revealed multiple large cystic spaces lined with a flattened or cuboidal epithelium, or, in some cases, there was no lining (Fig 2). The cysts appeared to represent either dilated bile ducts or degenerated mesenchy¬ mal spaces. The cysts were surrounded by dense fibrous connective tissue septae and interspersed in a loose myxoid stroma
Fig 1.—Mesenchymal hamartoma originating in the right hepatic lobe.
containing prominent ground substance, mesenchy¬
mal cells, blood vessels, and a proliferation of bile ducts. Within the interstitium and between the cysts were islands of compressed liver tissue. One specimen snowed multiple foci of extramedullary hematopoiesis. Within this matrix were
Fig 2.—Microscopic section revealing cysts of various sizes and shapes lined by the endothelium and the cuboidal bile duct epithelium surrounded by a pale connective tissue ("mesenchymal") stroma (he¬ matoxylin-eosin, original magnification 100). islands of normal or compressed liver tissue. Routine electron
microscopy was not performed. Follow-up information was available in 13 patients. The period of follow-up ranged from 1 month to 24 years (mean, 5 years). There were no recurrences or malignant transforma¬ tions. All patients were doing well and were free of symptoms.
COMMENT
Benign liver tumors in children may be divided into two major groups: those of epithelial derivation, including simple cysts, focal nodular hyperplasia, and adenomas; and those of mesenchymal derivation, including cavernous hemangiomas, capillary hemangioma (hemangioendotheliomas), and hamartomas.13 Benign mesenchymal tumors of the liver are more common than their epithelial counterparts.3 Mesenchymal hamartoma of the liver is considered to be an uncommon developmental anomaly seen almost exclusively in children younger than 2 years,4 although presentation in older children
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
has been
reported.5"8 It is generally regarded as the second
benign liver lesion in children, following hemangiomas.9 Mesenchymal hamartoma of the liver bears no relationship to cystadenoma with mesenchymal stroma of the liver and bile ducts. Cystadenoma with mesenchymal stroma is a premalignant lesion composed of cysts lined with colum¬ nar mucous-secreting epithelium and a cellular stroma resem¬ bling primitive mesenchyme. It is seen almost exclusively in female patients, most commonly in the fifth decade of life.10 The exact pathogenesis of mesenchymal hamartoma is not clear, but the prevalent theory is that it represents aberrant development of primitive mesenchyme in the portal tracts, most likely from bile ducts.11 This theory is supported by the predominance of proliferating bile ducts seen histologically. It is thought that the anomaly occurs late in embryogenesis, most
common
the liver maintains its lobular architecture and connection to the biliary tree. The lesion is thought to spread along portal tracts, entrapping islands of liver tissue as it grows. " Most investigators believe that the solid portion of the lesion is developed by the peripartum period. Stocker and Ishak4 postulated that the rapid enlargement of the tumor, manifested by increasing abdominal distention, is caused by cystic degeneration of the mesenchyme with secondary fluid accumulation within cysts, obstruction and dilatation of lym¬ phatics, or both. By far, the most common presenting symptom in patients with mesenchymal hamartoma of the liver is abdominal dis¬ tention, with or without the presence of a discrete mass. Associated symptoms are rare, the most significant being respiratory embarrassment from interference with normal ventilatory mechanics by a large hepatic mass. Cachexia may be present. Roentgenographic evaluation will usually establish the di¬ agnosis. Plain films of the abdomen and gastrointestinal tract contrast studies are not useful. Ultrasonography is the most informative examination, and we believe it should be used as the primary screening test for children with increasing ab¬ dominal distention or a hepatic mass. Most hepatic masses in the pediatrie age group are solid. The differential diagnosis of a cystic lesion is limited and includes mesenchymal hamar¬ toma, malignant mesenchymoma with a cystic component, and cystic hepatoblastoma (rare).1213 Malignant mesenchyas
of the liver (also called undifferentiated sarcoma of the liver) is mainly seen in an older age group. In a review of 31 moma
cases of patients referred to the Armed Forces Institute of Pathology, Washington, DC, 51.6% occurred in children aged 6 to 10 years. Only 16% were seen in children younger than 5 years.14 Clinically, most patients present with abdominal pain, in contradistinction to mesenchymal hamartoma of the liver.15 Teratomas and simple cysts are also possibilities, but these will usually show calcifications on plain films or ultrasonog¬ raphy. Computed tomography supports ultrasonography by showing the extent of the hepatic mass and its relationship to adjacent structures.13,16 Arteriograms may be useful but are not necessary. Once the diagnosis is made, removal of the lz
lesion is recommended. In our experience, there was no oper¬ ative mortality. There are four surgical options, and the procedure chosen must be individualized. If the tumor can easily be dissected from the surrounding tissue, enucleation is possible.5,17,18 This approach minimizes loss of normal liver tissue and decreases blood loss. With especially large lesions or in selected patients marsupialization of the cysts into the peritoneal cavity may be employed, although we have no experience with this tech¬ nique.19 The child in our series who underwent marsupializa¬ tion was alive and well 1 year after surgery, but was subse¬ quently unavailable for follow-up. Our preference has been excision of the hamartoma with a surrounding rim of normal liver tissue. While malignant mesenchymoma usually appears in an older age group and has a different clinical presentation, some crossover is possible. Excision is a safe procedure if it provides a clear margin. The final option is a formal hepatic lobectomy, which may be performed safely in children and was used in a number of our patients.19 Mesenchymal hamar¬ toma, however, is a benign lesion and we feel that an overly aggressive surgical approach is not usually justified. Diagnosis of mesenchymal hamartoma of the liver should be suspected in children under the age of 2 years with a suggestive medical history. This is confirmed by abdominal ultrasonography and computed tomography. Excision or marsupialization is recommended in all patients, with the expectation of very low surgical morbidity and mortality and an excellent long-term prognosis.
References 1. Edmonson HA, Peters RL. Tumors of the liver: pathologic features. Semin Roentgenol. 1983;18:75-83. 2. Ehren H, Mahour GH, Isaacs H. Benign liver tumors in infancy and childhood. Am JSurg. 1983;145:325-329. 3. Smith WL, Franken EA, Mitros FA. Liver tumors in children. Semin
Roentgenol. 1983;18:136-148. 4. Stocker JT, Ishak KG. Mesenchymal hamartoma of the liver: report of 30
and a review of the literature. Pediatr Pathol. 1983;1:245-267. 5. Grases PF, Matos-Villalobos M, Romero F, Lecuna-Torres V. Mesenchymal hamartoma of the liver. Gastroenterology. 1979;76:1466-1469. 6. Holmin T, Kullendorf CM. Diagnostic aids for benign tumors ofthe liver in children. Acta Paediatr Scand. 1981;70:755-757. 7. Salisbury JR, Darby AJ, Pormann BC. Mesenchymal hamartoma of the liver: report of an unusual case. Postgrad Med J. 1986;62:752-760. 8. Shah JP, Goldsmith HS, Huros AG. Hamartomas of the liver. Surgery. cases
1970;68:778-782. 9. Ein SH, Stephens CA. Benign liver tumors and cysts in childhood. J Pediatr Surg. 1974;9:847-851. 10. Wheeler DA, Edmonson HA. Cystadenoma with mesenchymal stroma (CMS) in the liver and bile ducts. Cancer. 1985;56:1434-1445. 11. Dehner LP, Ewing SL, Sumner HW. Infantile mesenchymal hamartoma
Histologic and ultrastructural observations. Arch Pathol. 1975;99:379-381. 12. Rosenbaum DM, Mindell HJ. Ultrasonographic findings in mesenchymal hamartoma of the liver. Radiology. 1980;138:425-427. 13. Stanley RJ, Dehner LP, Hesker AE. Primary malignant mesenchymal tumors (mesenchymoma) of the liver in childhood: an angiographic-pathologic study of three cases. Cancer. 1973;32:973-984. 14. Stocker JT, Ishak KG. Undifferentiated (embryonal) sarcoma of the liver. Cancer. 1978;42:336-348. 15. Newman KD, Schisgall R, Reaman G, Guzzetta PC. Malignant mesenchymoma or the liver in children. J Pediatr Surg. 1989;24:781-783. 16. Ros PR, Goodman ZD, Ishak KG, et al. Mesenchymal hamartoma of the liver: radiologic-pathologic correlation. Radiology. 1986;158:619-623. 17. Ito H, Kishiwaka TT, Toda T, Arai M, Muro H. Hepatic mesenchymal hamartoma of an infant. J Pediatr Surg. 1984;19:315-317. 18. Raffensberger JG, Gonzalez-Crussi F, Skeehan T. Mesenchymal hamartoma of the liver. J Pediatr Surg. 1983;18:585-587. 19. Randolph JG, Altman RP, Arensman RM, Matlack ME, Leikin SL. Liver resection in children with hepatic neoplasms. Ann Surg. 1978;187:599\x=req-\ of the liver.
605.
Downloaded From: http://archsurg.jamanetwork.com/ by a University of Michigan User on 06/15/2015
