Overview:
Hepatic tumors or liver tumors occur due to abnormal growth of the liver cells. These tumors can be cancerous (malignant) or non-cancerous (benign). As the liver consists of various cells, several distinct tumors can originate. Liver tumors are asymptomatic at first and might show symptoms when the tumor is large enough. Liver tumors can affect adults as well as children. Common malignant liver tumors in children include hepatoblastoma and hepatocellular carcinoma. Benign liver tumors in children occur as hemangiomas, hamartomas, and nodular hyperplasias.
What Is Mesenchymal Hamartoma?
Mesenchymal: A type of animal tissue that consists of undifferentiated cells that can give rise to bone, muscles, blood vessels, nerves, fat tissue, lymphatic network, etc.
Hamartoma: A non-cancerous tumor that consists of an abnormal mixture of cells found generally in the area where it grows.
Mesenchymal Hamartoma:
Mesenchymal hamartomas are uncommon tumors that develop in the liver of children. The tumor constitutes a mixture of blood vessels, hepatocytes (liver cells), and bile ducts (a network of tubes that carry bile juice required for digestion) embedded within an abundant connective tissue matrix. The pathology behind the tumor is not perceived yet.
What Causes Mesenchymal Hamartoma?
Studies have found that an abnormal expression of chromosome 19 leads to the mutation in the DICER1 gene that causes the development of mesenchymal hamartoma in children.
How Commonly Does Mesenchymal Hamartoma Occur?
Mesenchymal hamartomas represent 8 % of all pediatric liver tumors. They occur in children and neonates within the first two years after birth. 75 % of the affected children are less than a year old. Rarely do these tumors occur in adults. Male children are twice more commonly affected than female children (60 % to 70 % of cases occur in males).
Which Syndrome Is Associated With Mesenchymal Hamartoma?
1. Beckwith-Wiedemann syndrome (BWS) - Characterized by a large tongue (macroglossia), defects in the abdominal wall, ear abnormalities, and increased risk for embryonic tumors.
What Are the Signs and Symptoms of Mesenchymal Hamartoma?
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Mesenchymal hamartomas usually remain asymptomatic unless they are significant.
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The tumor commonly develops from the right lobe of the liver.
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Mesenchymal hamartomas can be rarely associated with embryonal sarcoma (a rare malignant tumor developing from mesenchymal tissue).
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In females, the tumor causes abdominal pain and prominent uterine fibroids.
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Large tumors cause abdominal distension and respiratory distress in children.
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A common feature of mesenchymal hamartoma is elevated tumor marker AFP (alpha-fetoprotein) levels.
How Is Mesenchymal Hamartoma Diagnosed?
1. Conventional Radiographs:
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The tumor looks disorganized, with a variable amount of soft tissue on a radiograph.
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The lesion appears to have a cavity-like feature called cysts.
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Sometimes, it can appear solid without any cystic cavities.
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The tumor usually measures 12 cm to 15 cm with septations in between.
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Calcified regions in the tumor are seen as radiopaque areas on the radiographs.
2. Ultrasound:
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On an ultrasound, the lesion appears multicystic between solid components.
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Peduncles or stalk-like structures appear on the report.
3. Computed Tomography (CT):
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The tumor has a heterogeneous (irregular) appearance, and solid portions look like swiss cheese.
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Solid portions appear thick and enhanced.
4. Magnetic Resonance Imaging (MRI):
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The tumor appears similar, with prominent cystic components visible depending on the protein and fluid content.
5. Angiography:
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It is not a diagnostic tool, but it shows increased blood supply around the tumor's borders.
What Is the Prognosis and Treatment of Mesenchymal Hamartoma?
Mesenchymal hamartomas are best treated by surgery. As they are benign, surgical resection will ensure a good prognosis. Occasionally, these tumors have been treated with ultrasound-guided surgery, where the fluid inside the tumor is aspirated to reduce the tumor size. Once the tumor shrinks, surgery is carried out efficiently without any complications.
What Are the Complications Associated With Mesenchymal Hamartoma?
The complications associated with mesenchymal hamartoma are mainly due to its size. In addition, neonates are at risk of developing these fatal complications listed below:
1. Fetal Hydrops - It is a fatal condition characterized by an abnormal fluid accumulation in the fetal compartment. It includes ascites (fluid accumulation in the abdomen), pleural effusion (fluid accumulation around the lungs), and skin edema (swelling due to fluid accumulation).
2. Circulatory Complications - It occurs due to a large space-occupying lesion in the abdomen.
What Other Lesions Appear Similar to Mesenchymal Hamartoma?
Several lesions can look similar to mesenchymal hamartoma on radiographs, CT, and MRI scans.Therefore, the clinician must rule out other similar lesions before confirming the diagnosis.
These lesions include:
1. Liver Abscess - The accumulation of pus due to infection causes a liver abscess. It is common in developing countries, and it leads to severe complications.
2. Hepatoblastoma - It is a rare cancerous tumor that originates from liver cells. Hepatoblastoma is common in children and develops in the liver’s right lobe.
3. Infantile Hemangioma - It is a common benign blood vessel tumor that proliferates and resolves after a few years. Some hemangiomas might undergo malignant or cancerous transformation.
4. Hepatic Cyst - It is a rare cavity-like lesion in the liver that mostly remains asymptomatic. Hepatic cysts should be surgically removed if the cyst is large.
5. Embryonal Sarcoma - It is a rare cancerous tumor that develops from the mesenchymal tissues of the liver. It commonly occurs in children and rarely in adults.
Conclusion:
Mesenchymal hamartomas are uncommon tumors that develop in children's livers. The tumor constitutes a mixture of blood vessels, liver cells, and bile ducts embedded within an abundant connective tissue matrix. The tumor remains asymptomatic until it reaches a significant size. Common symptoms include abdominal pain, swelling, respiratory distress, etc. The diagnosis is confirmed after advanced imaging like CT, MRI, ultrasound, etc. Surgical resection is the treatment of choice for mesenchymal hamartoma. As the tumor is non-cancerous, the prognosis is good if treated early.
