Lipoblastoma

Lipoblastoma (also known as fetal lipoma, embryonic lipoma, or infantile lipoblastoma) is a rare, benign soft tissue tumor composed of immature fat cells (lipoblasts) that primarily affects infants and young children, typically under the age of 3 years. The tumor arises from embryonal white fat and most commonly presents as a painless, rapidly growing soft tissue mass in the extremities, trunk, head and neck region, or retroperitoneum. Lipoblastomas can occur as well-circumscribed, encapsulated superficial masses (lipoblastoma) or as diffuse, non-encapsulated forms that infiltrate deeper tissues (lipoblastomatosis). The tumor is generally slow-growing but can become quite large and may cause symptoms depending on its location, including compression of adjacent structures such as airways, nerves, or blood vessels. Cytogenetic studies frequently reveal rearrangements involving chromosome 8, particularly affecting the PLAG1 gene at 8q12, which plays a role in the pathogenesis of this tumor. Lipoblastoma is not associated with malignant transformation, distinguishing it from liposarcoma, which is an important differential diagnosis. The primary treatment for lipoblastoma is complete surgical excision, which is generally curative. However, local recurrence can occur in approximately 14-25% of cases, particularly with the diffuse lipoblastomatosis variant or when complete resection is not achieved. In cases of recurrence, repeat surgical excision is typically successful. No chemotherapy or radiation therapy is required. Long-term prognosis is excellent, and spontaneous maturation of residual tumor into mature adipose tissue has been reported in some cases. Regular follow-up with clinical examination and imaging is recommended to monitor for recurrence.

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