Received: 30 October 2017
Accepted: 1 November 2017
Pathology of retroperitoneal sarcomas: A brief review
Salvatore L. Renne MD
O. Hans Iwenofu MD
Sarcoma and Pediatric Pathology Unit,
Department of Diagnostic Pathology and
Laboratory Medicine, Fondazione IRCCS
Istutito Nazionale dei Tumori, Milano, Italy
Department of Pathology & Laboratory
Medicine, Wexner Medical Center at The
Ohio State University, Columbus, Ohio
O. Hans Iwenofu, MD, Department of
Pathology and Laboratory Medicine, Wexner
Medical Center at The Ohio State University,
410 West 10th Avenue, Columbus, OH
Sarcomas represent a highly heterogeneous group of tumors as reflected in the
significant overlap between their histologic phenotypes between the different types,
posing diagnostic challenges for the pathologist. Definitive tumor classification is
increasingly important because of prognostication and emergence of targeted
therapies for some of the sarcoma types. In this review, we highlight pertinent
pathologic and molecular aspects of sarcomas common in the retroperitoneum,
relevant to the surgical oncologist.
histopathology, retroperitoneum, sarcomas
Sarcomas represent the rarest form of solid tumor malignancies,
accounting for <1% of tumors in the adult population with over 50
recognized histologic types, and numerous subtypes. Some of the
histologic types occur with a high frequency in the retroperitoneum
where their varied histologic patterns can overlap, especially in the
context of limited sampling, potentially leading to a diagnostic pitfall.
The diagnosis of sarcoma can, at times, be notoriously challenging for
pathologists, particularly those without subspecialty expertise. Defini-
tive classification of a tumor often requires integration of clinical
history and diagnostic imaging results, in addition to judicious
application of ancillary techniques such as immunohistochemistry,
cytogenetics and molecular pathology. The latter is particularly
important in view of the emergence of personalized medicine based
of molecularly targeted therapy. In this review, we highlight pertinent
pathologic and molecular aspects of sarcomas common in the
retroperitoneum, relevant to the surgical oncologist.
Well-differentiated liposarcoma (WDLS) is a locally aggressive
malignant mesenchymal neoplasm composed of mature adipose tissue
with nuclear atypia in either or both stromal cells and adipocytes.
Tumors are characterized by sheets of adipocytes with variability in
size and shape, with hyperchromatic nuclei and/or broad cellular
septae containing cells with enlarged and hyperchromatic nuclei;
multinucleation is common.
Noteworthy, atypical lipomatous tumor
(ALT) is a term reserved for histologically and genetically identical
tumors, but which are located outside the retroperitoneum in
extremity and trunk sites, rendering it complete surgical.
WDLS comprises the largest subset of malignant adipocytic neoplasm,
accounting for approximately 40-45% of all liposarcomas.
Tumors typically present as a painless mass in deep soft tissue. Some
are identified serendipitously in the course of radiographic work-up for
other conditions, or as part of wellness evaluations; others are
identified following weight loss.
The histologic patterns are broadly divided into three morphologic
subtypes: adipocytic (lipoma-like), sclerosing and inflammatory.
Regardless of the pattern that dominates, the classic diagnostic
histopathology finding often rests with identification of the
© 2017 Wiley Periodicals, Inc. wileyonlinelibrary.com/journal/jso J Surg Oncol. 2018;117:12–24.