Primary tumours of the liver are uncommon in childhood. Of these, more than two-thirds are malignant. As such, benign hepatic tumours are often not considered in the differential diagnosis of a hepatic mass in childhood. We report a case of hepatic mesenchymal hamartoma, a rare benign tumour, in a 10-month-old infant. This tumour is characterised by an admixture of ductal structures within a copious loose connective tissue stroma. Only approximately 160 cases had been reported in the literature. Awareness of the ultrasound (U/S) and computed tomography (CT) features, although not diagnostic, is helpful in distinguishing it from the more common malignant tumours. A correct preoperative diagnosis is important as surgical excision is often curative.
Here the first case in the literature of both mesenchymal hamartoma and malignant mesenchymoma occurring in a 6-year-old male child, at different times and at different sites in the liver, and also the possible malignant transformation of a mesenchymal hamartoma is reported. The tumor developed from a lesion in the right lobe that was overlooked initially during a left lateral segmentectomy at 18 months of age for a mesenchymal hamartoma. Malignant mesenchymoma is a rare and aggressive tumor. The origin of this tumor is not well understood. There has been no direct support to the hypothesis that malignant mesenchymoma may be the malignant counterpart of mesenchymal hamartoma. The authors provide clinical and histopathologic evidence in our case that suggests the possibility of malignant mesenchymoma arising from a mesenchymal hamartoma. This case emphasizes the need for complete removal of mesenchymal hamartoma and the need for long-term follow-up to detect multifocal lesion or malignant transformation.