Discussion
Lipoblastoma is a rare, fat-containing mesenchymal tumor that lacks
mature adipocytes (2, 6). Despite the lack of fundamental pathological
differentiation, patients might present with a lipoblastoma, an
encapsulated superficial focal lesion or an infiltrative aggressive
lesion known as lipoblastomastosis, which often tends to be deep and
infiltrative (3–5).Lipoblastoma accounts for 1% of all childhood
tumors (6), and 90% of cases are diagnosed in children under the age of
3 years (3). Lipoblastoma has a male predominance with a ratio of 4:1
(1). It primarily affects the trunk and extremities due to their high
immature fat content (3, 5). Patients can develop symptoms following
compression of nearby nerves, blood vessels, and airways (2, 7, 8).
However, asymptomatic growth leading to large size is more likely to
occur in accommodating compartments, such as the deeper retroperitoneum
(9), including the rare presacral location. In a retrospective case
review by Spătaru et al. (10), among 8 patients, only 1 was located in
the presacral region.
Lipoblastomas are derived from embryonic white cells, and unlike
lipomas, they lack mature adipocytes (6). Macroscopically, lipoblastomas
are usually soft and well-defined lesions with yellow-white cross
sections (2, 6). Microscopy identifies multi-vacuolated adipocytes,
fibrous septa, and myxoid stroma (2, 6).
A wide variety of imaging modalities reflect the lesion’s primary
fat-containing nature (2, 3). Lipoblastoma displays hyperechogeneity on
ultrasound, hypodensity on CT, hyperintense signal on T1 and T2
sequences, and low signal on fat sat-MRI (2, 3). However, an immature
lipoblastoma can appear on a T1-weighted image with an average signal
intensity, and the intensity of T2-weighted images varies depending on
the amount of myxoid and fibrous components (5). The lesion shows
enhanced septas and solid components in post-contrast images (7).
Despite being a benign tumor, lipoblastoma can appear aggressive locally
and present with features like neurovascular encasement, compartmental
invasion, diffuse infiltration, and intraspinal involvement (10).
When a young pediatric patient has a mesenchymal soft tissue
fat-containing mass, lipoblastoma, lipoma, teratoma, and liposarcoma are
among the possible differential diagnoses (6). Teratomas are a less
likely candidate when other elements of the germ cell tissue, such as
calcifications, are absent (3, 11).The possibility of lipoma is also
less likely, owing to the presence of non-fatty soft tissue components
and its rare occurrence in a very young patient (6, 11, 12). Although
the diagnosis of liposarcoma, particularly the myxoid form, is
consistent with the presence of a non-fatty soft tissue component in a
primarily fatty lesion, it is important to note that liposarcomas are
extremely uncommon in children under the age of five (11, 12).
Although lipoblastoma and lipoblastomatosis are benign tumor with no
potential for metastases or malignant transformation, they carry a
non-negligible risk of recurrence. A systemic review by Dao et al. (13)
reported a pooled recurrence rate of 16.8%, which was higher for
incompletely resected tumors as well as in lipoblastomatosis when
compared to lipoblastomas. This makes a complete surgical tumor excision
the ideal treatment of choice (3, 8). Especially for infants, such
aggressive radical surgery can be mutilating; therefore, we prefer
non-mutilating wide local excision whenever possible (4). Given
the risk of recurrence, follow-up for a minimum of 5 years is advised (9).