Lipoblastoma and lipoblastomatosis are rare, benign, soft-tissue tumors of embryonal fat occurring primarily in children younger than 3 years. They arise from the continued proliferation of lipoblasts in white fat after birth.¹,⁴³

Jaffe first used the term “lipoblastoma” in 1926 for lipomatous tumors containing immature fat cells, which did not metastasize.² In 1958, Vellios et al³ applied the term “lipoblastomatosis” to these tumors. They noted the presence of adipocytes in various stages of differentiation and compared these with the temporal stages of embryonic white fat development based on morphologic criteria. They suggested that these tumors represent an arrest in the development of fat maturation primarily in areas of the body where postnatal fat maturation occurs, such as the axilla, mediastinum, and retroperitoneum. In 1977, Gibbs et al⁴ applied the term “lipoblastomatosis” to all benign lipoblastic adipose tumors and used the term “lipoblastoma” for tumors of brown fat, otherwise known as hibernomas. More precise morphologic criteria for diagnosis were established in 1973 when Chung and Enzinger⁵ distinguished two distinct forms of this same entity. They designated the term “lipoblastomatosis” for a more diffuse, infiltrative form of the tumor and reserved the term “lipoblastoma” for the more circumscribed encapsulated form. Aside from this difference, these two forms of the tumor have identical cell morphology histologically. In 2000, O’Donnell et al⁶ argued that because lipoblastoma does not metastasize, the term blastoma was confusing. They proposed replacing it with the term “infantile lipoma.” However, the terminology proposed by Chung and Enzinger is still the most commonly used nomenclature.

Of the 410 cases of lipoblastoma and lipoblastomatosis reported in the literature to date, approximately 68% were encapsulated and represented lipoblastoma, and 32% showed a more diffuse growth pattern, more consistent with lipoblastomatosis.⁷ Tumors occurred most frequently on the trunk and extremities (80%) and much less commonly on the head and neck (17%). Of the latter group, most were seen in the neck, with only 5% occurring on the face and head.

Lipoblastoma is a well-circumscribed encapsulated lesion.⁷,⁸ It has been reported in patients from birth to 60 years of age, but the mean age at presentation is 3.2 years.⁷ Nearly 80% of patients are younger than 3 years, and 94% are younger than 10 years. Only 2% are older than 20 years at presentation. Although some earlier reports suggested a strong male predominance of as high as 4:1,10 larger reviews have shown only a slight male predominance of 1.5:1.⁷ The most common sites of involvement are on the extremities and trunk,⁷,¹⁰,¹¹,¹² and less frequently in the abdomen, retroperitoneum, mediastinum, axilla, groin, inguinoscrotal, labia, vulva, and gluteal region. Occurrence on the head and neck is relatively uncommon.⁷,¹⁰,¹¹,¹³,¹⁴,¹⁵,¹⁶

To date, only three cases of lipoblastoma have been described in the eyelid. Enghardt and Warren¹⁷ reported a congenital lipoblastoma in a 13-month-old female patient with a mass in the eyelid anterior to the orbital septum. Adams et al¹⁸ presented a case of a 16-month-old male patient with a lipoblastoma in the eyelid and anterior lateral orbit associated with eyelid edema and strabismus. Singh et al¹⁹ presented a rare case of a large congenital lipoblastoma of the scalp that extended into the brow and eyelid. Three additional cases involved the orbit. Seider et al²⁰ described a newborn infant with a congenital lipoblastoma involving the nasal cavity and orbit. Hwang et al²¹ reported a 3-month-old infant with an orbital lipoblastoma since birth, 2 cm in size, and causing 4 diopters of astigmatism. A previous case of orbital lipoblastoma was described by Bernolet and Jaeger in 1949.²² One case of lipoblastomatosis has been described extending from the eyelid into the anterior orbit.⁷

Diagnostic imaging of lipoblastoma and lipoblastomatosis can be helpful in clinical diagnosis. Ultrasound may demonstrate a diffuse to well-defined mass with weak heterogeneous
echogenicity.²³ High internal echoes represent cellular and septate areas, and low echoes represent myxoid and fatty areas. On radiologic imaging, the appearance depends on the amount of myxoid stroma and fibrous septa among the fat. On CT, lipoblastoma appear as a well-defined or diffuse, heterogeneous, hypodense mass. Areas of low attenuation represent fat,²⁴,²⁵,²⁶ and enhancement can be seen in areas of rich capillary network and in the interlobular septa.²⁷ MRI is the modality of choice to define the extent of the mass and the possibility of local invasion. T1-weighted images demonstrate a heterogeneous mass that is isointense to slightly hypointense to subcutaneous fat. T2-weighted images reveal a heterogeneous lesion with areas of high signal intensity.²⁸,²⁹,³⁰ Lesions become markedly hypointense with fat suppression.

Malignant transformation has not been documented in lipoblastoma or lipoblastomatosis. Recurrent tumors may transform into more mature lipomatous tumors, such as a lipoma.⁹,³¹,³²