110 subfascial lipomatous tumors. MR and CT findings versus histopathological diagnosis and cytogenetic analysis.
OBJECTIVE
To evaluate whether liposarcoma, atypical lipomatous tumors and lipoma can be differentiated radiologically.


METHODS
We have retrospectively analyzed CT and/or MR images of 110 subfascial lipomatous lesions. The amount of fat within the tumors was visually graded from the images as: none, 1-75%, 75-95% or 95-100%. The structure of non-fatty tumor components was compared. The images were compared to histopathology and in 37 cases to cytogenetic findings.


RESULTS
Only 4 of 20 liposarcomas contained fat. All 4 lesions, histopathologically diagnosed as atypical lipomatous tumors, contained fat but less than 75% of tumor volume. All lesions with more fat than 75% of tumor volume were histologically diagnosed as lipomas. However, one-third of the karyotyped lipomas had ring chromosomes which are considered typical for atypical lipomatous tumors.


CONCLUSIONS
When a tumor is composed more or less solely of fat, the diagnosis of a lipoma or atypical lipomatous tumor with a phenotype simulating a lipoma can be assumed. When the fat content is less than 75% of the tumor volume or non-fatty nodules are found, biopsies from different tumor components have to be performed to exclude malignancy. When no fat is found, imaging does not help in differentiating lipoma or liposarcoma from other soft tissue tumors.
Einarsdottir
H
H
Department of Diagnostic Radiology, Karolinska Hospital, Stockholm, Sweden.
Söderlund
V
V
Larsson
O
O
Mandahl
N
N
Bauer
H C
HC
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005205:Fascia; D005260:Female; D006801:Humans; D008067:Lipoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D008080:Liposarcoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D014057:Tomography, X-Ray Computed