Analysis of clinical features of lipoblastoma in children.

OBJECTIVE: A lipoblastoma is pathologically benign but often recurs. Due to its rarity, studies are scarce. The purpose of this study was to investigate the clinical characteristics of lipoblastoma occurring in children and to detect any correlations with the expression of Ki-67. PARTICIPANTS: From 1998 to 2010, 33 patients were diagnosed with lipoblastoma at Seoul National University Children's Hospital. METHODS: Ki-67 immunohistochemistry staining of the tumor tissue was performed. RESULTS: A total of 33 patients (64% males) were enrolled in the study, with a mean age of 28 month. Eleven and 22 lesions were deep and superficial, respectively. Complete excisions were performed for 30 patients, and three underwent incomplete excisions. Two patients who underwent incomplete excision subsequently underwent a second operation due to tumor regrowth, and one patient had a recurrence despite complete excision. There was no statistically significant correlation observed between the tumor size or recurrence and the expression of Ki-67. CONCLUSIONS: Lipoblastoma requires an accurate diagnosis and operative resection to alleviate the symptoms induced by its growth. Incompletely resected tumor may regrow; therefore, complete excision is the treatment of choice. Continuous follow-up is needed to monitor for recurrence of disease, even after a complete excision.

Fine-needle aspiration of lipoblastoma: Cytological, molecular, and clinical features.

BACKGROUND: Lipoblastomas are rare, benign adipocytic tumors that present mostly during infancy. In about 70% of cases, these tumors carry abnormalities in chromosome 8, mainly leading to rearrangements of the PLAG1 gene. METHODS: We report a series of histologically proven lipoblastomas with previous fine-needle aspiration (FNA) cytology from 9 patients (n = 10 samples) and describe their clinical, cytological, and molecular features. RESULTS: Our cohort included 5 boys and 4 girls (median age, 2.5 years [range, 10 months to 13 years]) who presented with soft tissue masses in the thorax (n = 3), abdomen (n = 2), axilla (n = 2), and thigh (n = 2). In 1 patient, the FNA diagnosis was inconclusive due to hypocellularity, and in another patient a diagnosis of benign lipomatous tumor was made. In the remaining 8 samples (one of which confirmed relapse), a correct preoperative FNA diagnosis was rendered. Smears were hypo- to moderately cellular and contained fragments of mature adipose tissue with thin branching vessels admixed with some lipoblasts in a myxoid matrix. Spindle cells and naked oval nuclei with no atypia were observed in the background. Of the 4 patients tested for PLAG1 rearrangement using FISH probes, 3 harbored this alteration (1 was made on a FNA smear and 1 was made in a tumor imprint). All the patients are alive and well, except for 1 patient with a retroperitoneal tumor who, after an initial incomplete excision, died of local disease progression. CONCLUSION: FNA, especially if used together with molecular biology techniques (eg, PLAG1 FISH analysis), is a reliable and accurate diagnostic tool. Cancer Cytopathol 2017;125:934-9. © 2017 American Cancer Society.

Desmin-positivity in spindle cells: under-recognized immunophenotype of lipoblastoma.

Lipoblastoma is a distinct benign fatty tumor composed of adipocytes, lipoblasts, and primitive mesenchymal cells with a myxoid stroma. Lipoblastoma harbors characteristic fusion genes involving the PLAG1, resulting in aberrant expression of PLAG1. However, the nature of the primitive mesenchymal cells remains obscure. In our routine pathology practice, we noticed desmin-positive spindle mesenchymal cells in lipoblastomas, which is a hitherto poorly described phenomenon. Thus, we examined the expression of several myogenic markers including desmin in a variety of 95 mesenchymal tumors with fatty elements. Fourteen of the 15 lipoblastomas examined contained desmin-positive spindle cells, which also showed nuclear expression of PLAG1, whereas α-smooth muscle actin, muscle specific actin, h-caldesmon, and myogenin were negative. Some spindle cells in subsets of atypical lipomatous tumors/well differentiated liposarcomas (6/20), dedifferentiated liposarcomas (11/31) and pleomorphic liposarcomas (2/10) were positive for actins and/or desmin, supporting focal myofibroblastic or smooth muscle differentiation. The other tumors, including 11 myxoid/round cell liposarcomas, four spindle cell lipomas, and four lipofibromatoses, were negative for all of the myogenic markers assessed. The almost consistent desmin expression in spindle mesenchymal cells suggests a potential diagnostic utility of this marker and myofibroblastic phenotype of fractions in lipoblastoma cells.

Giant omental lipoblastoma and CD56 expression.

We report a case of giant omental lipoblastoma in a 13-month-old boy, which was treated successfully by total excision. Tumor cells were positive for S100, CD34 and CD56. This is the first report of lipoblastoma expressing CD56, a fact that could be used to differentiate lipoblastoma from liposarcoma.