title: Critical histopathological analysis of 25 dedifferentiated liposarcomas, including uncommon variants, reviewed at a Tertiary Cancer Referral Center.
abstract: BACKGROUND
  De-differentiated liposarcomas (DDLSs) are uncommon tumors with a wide histopathological spectrum.
  
  
  METHODS
  Over an 8-year period (2003-2011), 25 DDLSs, after review, were critically analyzed for histopathological features.
  
  
  RESULTS
  Twenty-five tumors, in 14 men and 11 women (M: F = 1.2:1), with age range of 22-88 years (mean, 53.9), occurred in retroperitoneum (14) (56%), thigh (3) (12%), paratesticular region (3) (12%), chest wall (2) (8%), leg (1) (4%), shoulder (1) (4%), and groin (1) (4%). Tumor size (21 tumors) varied from 7.5 to 25 cm (mean, 17.5). Histopathologically, DD component was high grade in 19 (76%) and low grade in 6 (24%) tumors. Whereas the most common WD component was adipocytic type; the most common DD component was pleomorphic sarcomatous (13) (52%), followed by myxofibrosarcomatous (MFS)-type (6) (24%). Low-grade DD components included MFS (2), fibrosarcoma (2), myogenic/myofibroblastic type (1), and IMFT-type (1). Three tumors displayed meningothelial-like whorls and metaplastic bone formation. Heterologous elements, noted in 11 (44%) tumors, included bone (8) and rhabdomyoblastic differentiation (2). Two tumors displayed homologous differentiation, reinforced with MDM2 staining. S100-P was diffusely positive in WD components (5/7) and focally in DD components (2/9). All patients were treated with surgery, including 10, who underwent adjuvant radiotherapy. Outcomes (16 patients, 64%), over 1-48 months included 10 patients free of disease, 4 died of disease, and 2 patients alive with disease.
  
  
  CONCLUSIONS
  This study forms the largest documentation of DDLSs, including its wide histopathological spectrum, from our country. Rare cases overlap with pleomorphic liposarcoma. S100-P and MDM2 are useful in substantiating adipocytic differentiation, especially in selected cases. Analysis of adequate tumor sections is vital for correct identification of a DDLS. Surgical excision with adjuvant RT forms optimal treatment.
authors.affiliation: Department of Pathology, Tata Memorial Hospital, Mumbai, India.
authors.forename: Bharat
authors.initials: B
authors.lastname: Rekhi
authors.forename: Pooja
authors.initials: P
authors.lastname: Navale
authors.forename: N A
authors.initials: NA
authors.lastname: Jambhekar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D007194:India; D008080:Liposarcoma / Q000175:diagnosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D051736:Proto-Oncogene Proteins c-mdm2 / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D062606:Tertiary Care Centers
chemical_list: D009418:S100 Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2