Mesenchymal Hamartoma in Children: A Diagnostic Challenge

Abstract

Mesenchymal hamartoma is a benign tumor of the liver with a poorly understood pathogenesis. It is uncommon in older children, especially after 2 years of age. The signs and symptoms may be nonspecific; therefore, a high index of suspicion is required for diagnosis and treatment. We report a 5-year-old previously healthy male who presented with acute abdominal pain, fatigue, and fever. He was diagnosed with pneumonia initially and treated with antibiotics. A computed tomography (CT) scan done for evaluation of his persistent abdominal pain demonstrated a hepatic mass. Follow-up magnetic resonance imaging (MRI) of the liver demonstrated multiple serpiginous tubular-type structures, read as possible Caroli syndrome. He had a normal abdominal examination and normal biochemistries including alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, and alpha-fetoprotein. He was referred to our institution for second opinion. On further review of his imaging studies, the lesion was thought to be a mesenchymal hamartoma. He subsequently underwent resection of the mass. Pathology confirmed the diagnosis of mesenchymal hamartoma.

Hepatic mesenchymal hamartoma: An uncommon but important paediatric diagnosis

“…Mesenchymal hamartomas were first described in the literature by Edmondson in 1956. 2 Initially, these lesions were variably named as hepatic or giant lymphangiomas, bile duct fibroadenomas, and cavernous lympangiomatoid tumours before being grouped together under the term ‘mesenchymal hamartoma’. Association with polycystic kidney disease, congenital hepatic fibrosis and biliary hamartomas has been described.…”

“…Undifferentiated embryonal sarcomas, an even rarer entity, may be indistinguishable from cystic mesenchymal hamartomas. 1 , 2 , 3 , 4 …”

Pediatric Primary Hepatic Tumors: Diagnostic Considerations

“…The majority of cases present prior to the age of two, with a slight male predominance [ 17 , 18 ]. This is the second most common benign hepatic tumor presenting in infancy and young children, after infantile hemangioma [ 19 ]. Although the pathogenesis is not clear, the most widely accepted theory is that MH arises late in embryogenesis from the aberrant development of mesenchyme in the portal tracts [ 18 , 19 , 20 ].…”

“…This is the second most common benign hepatic tumor presenting in infancy and young children, after infantile hemangioma [ 19 ]. Although the pathogenesis is not clear, the most widely accepted theory is that MH arises late in embryogenesis from the aberrant development of mesenchyme in the portal tracts [ 18 , 19 , 20 ]. Rarely, MH can undergo malignant transformation into undifferentiated embryonal sarcoma [ 17 ].…”

“…In toddlers, small lesions are generally asymptomatic and often diagnosed incidentally on imaging studies but may present with nonspecific symptoms such as abdominal pain, fatigue, and fever. More commonly, the diagnosis is delayed until the tumor is larger enough to cause mass effect on surrounding structures and more severe symptoms [ 19 ]. AFP may be normal or elevated in this older age group due to the presence of normal hepatocytes within the tumor and may mimic the presentation of hepatoblastoma [ 18 ].…”