Lipoblastoma is a rare benign tumor that arises from embryonic white fat, occurring almost exclusively in infants and childhood. It is found most often on the limbs and trunk, and is benign in character with a lack of propensity to recur.1,2
There are few cases reported of lipoblastoma involving the orbit. Adams et al.3 reported the first case of orbital lipoblastoma in 1997, which encompassed histopathologic and radiologic findings of orbital lipoblastoma. A case of orbitonasal lipoblastoma was also reported in 2006.4 However, there are no previous studies that report clinico-radio-pathologic changes of orbital lipoblastoma over time.
We experienced a rare case of orbital lipoblastoma, showing temporal changes in magnetic resonance imaging findings. In this case report, we present changes in radiologic findings over time and the radiological–pathologic correlation, and infer the change of pathologic features of orbital lipoblastoma over time.
A 3-month-old male infant presented to our clinic with a palpable lump on the left upper eyelid that had been observed since birth. The patient was delivered spontaneously after a full-term pregnancy, with no history of any familial or genetic medical disorder.
On clinical examination, a soft, mobile mass approximately 2 × 1 cm in size was deeply palpable at the center of the left eyelid. Direct illumination by a hand-held illuminator revealed a translucent feature of the mass (Figure 1A). Other ocular examinations, including extraocular motility, slit-lamp examination, and funduscopy, were normal except for a significant astigmatism of 4.00 diopters noted in the left eye.
(A) Direct illumination by a hand-held illuminator reveals a translucent feature of the mass. At the age of 3 months, (B) fat-saturated T1-weighted imaging demonstrates a well-demarcated orbital mass of left eye with intermediate signal intensity, (C) T2-weighted imaging reveals an orbital mass with high signal intensity, and (D) gadolinium-enhanced T1-weighted imaging shows a well-enhanced orbital mass. At the age of 15 months, (E) T2-weighted imaging shows a reduction of signal intensity compared to the previous evaluation, with newly developed septum-like structures, and (F) gadolinium-enhanced T1-weighted imaging shows a mild enhancement in the orbital mass.
Magnetic resonance imaging (MRI) at the age of 3 months demonstrated a well-defined left upper eyelid mass with intermediate signal intensity on fat-saturated T1-weighted images (Figure 1B) and high signal intensity on T2-weighted images (Figure 1C). Gadolinium-enhanced fat-saturated T1-weighted images showed an enhancing orbital mass (Figure 1D). Due to the benign characteristics of the mass on imaging, the patient's parents declined surgical intervention and chose serial monitoring for any changes in clinical findings.
Follow-up MRI was performed when a slight increase in size of the mass from 12.7 × 5.4 to 16.7 × 10.7 mm was noted after 1 year. On T1-weighted images, no significant interval change in signal intensity was noticed. However, on T2-weighted images, the mass demonstrated a general reduction of signal intensity compared to the previous evaluation, a loss of homogeneity, and a newly noted septum-like structure of low signal intensity (Figure 1E). Only mild enhancement was noted on gadolinium-enhanced T1-weighted images during the follow-up evaluation, which was a significant change from the previously noted enhancement in the first evaluation (Figure 1F).
The patient underwent excisional biopsy through transcutaneous anterior orbitotomy. A distinct encapsulated yellowish mass measuring 1.2 × 1.0 × 1.0 cm was noted beneath the orbital septum. The mass was easily dissected from the surrounding tissue (Figure 2A).
(A) Gross pathologic examination shows an ovoid yellowish mass with encapsulation. (B) Hematoxylin–eosin staining shows hypocellular lobules with a mixture of adipocytes and myxoid stroma, separated by prominent fibrous septa (original magnification ×40). (C) Adipocytes in various stages of differentiation, including pre-adipocytes (hematoxylin–eosin, original magnification ×100). (D) The lobules contain a plexiform vascular pattern and abundant myxoid stroma (hematoxylin–eosin, original magnification ×200).
A histopathologic examination revealed that the tumor was composed of hypocellular lobules, with a mixture of adipocytes and myxoid stroma and separated by prominent fibrous septa (Figure 2B). The adipocytes were in various stages of differentiation, including pre-adipocytes (spindle- or stellate-shaped) (Figure 2C). Lobules also contained a plexiform vascular pattern and abundant myxoid stroma (Figure 2D). The features were highly suggestive of orbital lipoblastoma.
The patient was followed up for 12 months without any evidence of recurrence.
The term “lipoblastoma” was first used by Jaffe in 1926 to describe a benign tumor of immature fat cells.5 Since then, numerous cases of lipoblastoma have been reported. Chung and Enzinger6 reported 35 cases of lipoblastoma, which resulted in the largest published series. They observed that the most common presentation was a steadily growing mass. At diagnosis, 88% of their patients were younger than 3 years of age, with a median age of 1 year.
A remarkable feature of the current case is the difference between the MRI findings performed at the ages of 3 and 15 months. MRI performed at the age of 3 months demonstrated intermediate signal intensity on T1-weighted images, homogeneous high signal intensity on T2-weighted images, and marked enhancement on gadolinium-enhanced T1-weighted images. MRI performed at the age of 15 months showed a reduction of signal intensity and loss of homogeneity with septum-like structures of low signal intensity on T2-weighted images, and significantly less enhancement on gadolinium-enhanced T1-weighted images.
In the literature, MRI findings of lipoblastoma have been described in several case reports and small series.7 High signal intensity on T2-weighted images, variable degrees of signal intensity on T1-weighted images reflecting the proportion of mature fat cells, and mild or absent enhancement on gadolinium-enhanced T1-weighted images have been commonly reported in previous studies. A prior report of orbital lipoblastoma also showed similar characteristics of the aforementioned MRI findings.3
In this case, the MRI findings at the age of 15 months were similar to those of previously reported cases of lipoblastoma. However, the MRI findings at the age of 3 months were not suggestive of typical lipoblastoma; rather, they were suggestive of other lesions such as infantile hemangioma or vascular malformation. The authors presumed that those changes in the image findings were associated with the temporal changes of the pathologic components of the lipoblastoma.
In a study on the radiologic–pathologic correlation in lipoblastoma, Moholkar et al.7 reported that the imaging appearances depended on the composition of the lipoblastoma, in particular the proportion of myxoid stroma. The study also mentioned that the myxoid component, which can be prominent in younger patients, would correlate with enhancement. This could explain the MRI findings at the age of 3 months in our case.
Considering the temporal change of MRI findings in this case, we assume that the myxoid component predominates at a young age in lipoblastoma. As the patient grows older, the myxoid components regress and fibrous septa develop. This causes a reduction of signal intensity, development of a septum-like structure on T2-weighted images, and loss of enhancement on gadolinium-enhanced T1-weighted images. The proportion of mature fat cells does not seem to be changed by time because no significant change of signal intensity was noticed on T1-weighted images.
There are some cases in the literature regarding transformation of lipoblastoma. Duhaime et al.8 reported spontaneous maturation of cervical lipoblastoma into lipoma, and Kamel et al.9 reported transformation of cervical lipoblastoma into lipoma after chemotherapy. Additionally, Mognato et al.10 presented a spontaneous regression of femoral head lipoblastoma without any treatment. Like those cases mentioned, our case of orbital lipoblastoma seemed to change its composition as the child grew.
Lipoblastoma is a rare occurrence in the orbit and should be considered in the differential diagnosis of an orbital mass in children. Lipoblastoma may change its composition over time, which could result in the temporal changes in the radiologic findings. The diagnosis of lipoblastoma cannot rely solely on imaging; excision of the tumor and histopathologic studies are necessary to confirm the diagnosis.
- Mentzel T, Calonje E, Fletcher CD. Lipoblastoma and lipoblastomatosis: a clinicopathological study of 14 cases. Histopathology. 1993;23:527–533. doi:10.1111/j.1365-2559.1993.tb01238.x [CrossRef]
- Dilley AV, Patel DL, Hicks MJ, Brandt ML. Lipoblastoma: pathophysiology and surgical management. J Pediatr Surg. 2001;36:229–231. doi:10.1053/jpsu.2001.20060 [CrossRef]
- Adams RJ, Drwiega PJ, Rivera CA. Congenital orbital lipoblastoma: a pathologic and radiologic study. J Pediatr Ophthalmol Strabismus. 1997;34:194–196.
- Seider N, Gilboa M, Barishak YR, Miller B. Congenital combined orbitonasal lipoblastoma: clinico-pathologic study. Orbit. 2007;26:125–127. doi:10.1080/01676830600974852 [CrossRef]
- Jaffe RH. Recurrent lipomatous tumors of the groin: liposarcoma and lipoma pseudomyxomatodes. Arch Pathol. 1926;1:381–387.
- Chung EB, Enzinger FM. Benign lipoblastomatosis: an analysis of 35 cases. Cancer. 1973;32:482–492. doi:10.1002/1097-0142(197308)32:2<482::AID-CNCR2820320229>3.0.CO;2-E [CrossRef]
- Moholkar S, Sebire NJ, Roebuck DJ. Radiological-pathological correlation in lipoblastoma and lipoblastomatosis. Pediatr Radiol. 2006;36:851–856. doi:10.1007/s00247-006-0175-5 [CrossRef]
- Duhaime AC, Chatten J, Schut L, Rorke L. Cervical lipoblastomatosis with intraspinal extension and transformation to mature fat in a child. Childs Nerv Syst. 1987;3:304–306. doi:10.1007/BF00271830 [CrossRef]
- Kamel HA, Brennan PR, Farrell MA. Cervical epidural lipoblastomatosis: changing MR appearance after chemotherapy. AJNR Am J Neuroradiol. 1999;20:386–389.
- Mognato G, Cecchetto G, Carli M, et al. Is surgical treatment of lipoblastoma always necessary?J Pediatr Surg. 2000;35:1511–1513. doi:10.1053/jpsu.2000.16428 [CrossRef]