Age / Sex : 1 / M

Chief complaint: Palpable mass in the right sole

What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

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Courtesy: Ok Hwa Kim, Inje University Haeundae Paik Hospital

Lipoblastoma

Discussion

Findings:

Coronal T1WI (A) and T2WI (B), and axial STIR T2WI (C) of the right forefoot show a well-defined, predominantly fatty mass with some internal non-adipose components, located between the intrinsic muscles of the sole. Axial fat- suppressed gadolinium-enhanced T1WI (D) shows the localized, heterogeneous contrast enhancement in the mass. On radiographs of the foot, there reveal no bony abnormality of the foot (not seen).

Differential Diagnosis:

Liposarcoma, Lipoma, Teratoma

Diagnosis:

Lipoblastoma

Discussion:

Lipoblastoma is a rare, benign, encapsulated tumor arising from embryonic white fat, which occurs almost exclusively in infants and children. On histology they typically contain variably differentiated adipocytes, primitive mesenchymal cells, myxoid matrix, and fibrous trabeculae. Published reports showed that 80–90% of cases occur before aged 3 years, and 40% before aged 1 year. It most often occurs in the extremities and trunk, although it can be seen in other areas. On MRI, the mass is hyperintense on T2WI. T1WI show a variable degree of fat in the tumor, possibly reflecting the proportion of mature fat cells in the lesion. Many lesions appear to be mostly fat, in which case contrast enhancement is usually absent or mild and localized. Other tumors, however, show only small areas of increased signal on T1WI, often with quite marked heterogeneous enhancement. There is a recurrence rate of up to 20% with no recorded case of metastasis. Some cases have matured into lipomas. The treatment of choice is a complete but conservative excision.

References:

1.Kok KY, Telisinghe PU. Lipoblastoma: clinical features, treatment, and outcome. World J Surg 2010;34(7):1517-22

2. Moholkar S, Sebire NJ, Roebuck DJ. Radiological-pathological correlation in lipoblastoma and lipoblastomatosis. Pediatr Radiol 2006;36(8):851-6