A rare case of inguinolabial lipoblastoma in a 13-month-old female.

Lipoblastoma is a rare, rapidly growing, benign mesenchymal tumor composed of various stages of maturing adipocytes that most often occurs in children under the age of 3. The common locations are the extremities and the trunk. Presentation in the genitoinguinal area is rare. We report a case of a 13-month-old female infant with a 4-month history of a progressively enlarging left labial mass that encompassed her left labium majora and inguinal region. Pelvic MRI confirmed growth from previous ultrasound size of 3 × 2 × 1 cm to 7 × 2 × 2 cm. Composition was suggestive of adipose tissue. The mass was excised through a left inguinal incision. The final pathology results described a lipoblastoma. Six year follow-up has not revealed any signs or symptoms of recurrence. Circumscribed lipoblastomas should be distinguished from their infiltrative counterpart, diffuse lipoblastoma or lipoblastomatosis, which can be more difficult to excise and thus, more likely to recur. Lipoblastoma should also be distinguished from myxoid liposarcoma, which has malignant features, carries a high risk of recurrence, and requires a more aggressive management protocol. Although rare, lipoblastoma should be considered as part of the differential diagnosis of a rapidly growing vulvar mass in prepubertal children.