Cytogenetic and molecular cytogenetic ﬁndings
in dedifferentiated liposarcoma with neural-like whorling
pattern and metaplastic bone formation
Ricardo S. Macarenco
, Michele Erickson-Johnson, Xiaoke Wang, Robert B. Jenkins,
Antonio G. Nascimento, Andre M. Oliveira
Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street NW, Rochester, MN USA 55905
Received 28 April 2006; accepted 5 July 2006
Dedifferentiated liposarcoma is a subtype of liposarcoma characterized by juxtaposition of well-dif-
ferentiated liposarcoma with a nonadipocytic sarcoma. A peculiar form of dedifferentiated liposar-
coma has been described, characterized by a nonlipogenic component with a neural-like whorling
pattern of growth and metaplastic bone formation. We report the cytogenetic and molecular genetic
ﬁndings of this peculiar form of dedifferentiation in a retroperitoneal tumor found in a 58-year-old
female. The neoplasm had typical histologic ﬁndings and a complex karyotype characterized by
several numeric and structural chromosomal abnormalities, including the presence of ring and giant
rod chromosomes. Molecular cytogenetic studies found high levels of ampliﬁcation of the MDM2
oncogene, consistent with the ampliﬁcation of the 12q14 chromosome band, a cytogenetic abnor-
mality commonly found in these tumors. These ﬁndings indicate that, despite its unique and pecu-
liar morphologic features, this unusual type of dedifferentiated liposarcoma shares many of the
cytogenetic features and molecular genetic abnormalities found in other forms of dedifferentiation.
The speciﬁc cytogenetics and molecular determinants of these peculiar morphologic ﬁndings, how-
ever, remain unknown. Ó 2007 Elsevier Inc. All rights reserved.
Well-differentiated liposarcoma (WDL) is among the
most common malignant soft-tissue tumors. Occasionally,
and especially in the retroperitoneum, WDL can exhibit
a sudden transition to a nonlipogenic sarcoma, known as
dedifferentiated liposarcoma (DDL). The dedifferentiated
areas are often morphologically similar to high-grade un-
differentiated pleomorphic sarcoma and adult-type ﬁbrosar-
coma, but may also have areas similar to myxoﬁbrosarcoma
or undergo heterologous differentiation into rhabdomyosar-
coma, leiomyosarcoma, angiosarcoma, chondrosarcoma,
and osteosarcoma [1e6]. A peculiar and intriguing form
of DDL described by Nascimento et al.  and subse-
quently by others  is characterized by the juxtaposition
of WDL with a spindle cell proliferation exhibiting a neu-
ral-like or meningothelial-like whorling growth pattern and
metaplastic bone formation. We report the cytogenetic and
molecular cytogenetic analysis of this peculiar and unusual
form of DDL.
2. Materials and methods
2.1. Case report
A 58-year-old woman with a long history of hyperten-
sion and renal ﬁbromuscular dysplasia presented with
a 5-cm retroperitoneal mass incidentally discovered on ab-
dominal ultrasonography during routine evaluation of her
renal disease. The initial diagnosis on the biopsy specimen
was high-grade unclassiﬁable sarcoma. Surgical resection
was performed, and histologic examination disclosed a bi-
phasic neoplasia with two distinct components with a well-
demarcated and sudden transition between them. The ﬁrst
component was a WDL with lipoma-like and sclerosing
features. The other component presented a whorled growth
pattern simulating a neural tumor or a meningioma. Meta-
plastic bone formation was present throughout the dediffer-
entiated areas (Fig. 1).
Visiting Clinician at the Department of Anatomic Pathology from
CIPAX, Unidade de Patologia Cirurgica e Citopatologia de Sao Jose dos
Campos (SP), Brazil.
* Corresponding author. Tel.: 507-284-8917; fax: 507-284-2107.
E-mail address: Oliveira.Andre@mayo.edu (A.M. Oliveira).
0165-4608/07/$ e see front matter Ó 2007 Elsevier Inc. All rights reserved.
Cancer Genetics and Cytogenetics 172 (2007) 147e150