Immunohistochemical Analysis of Anaplastic Lymphoma
Kinase Expression in Deep Soft Tissue Calcifying Fibrous
Pseudotumor: Evidence of a Late Sclerosing Stage of
Inflammatory Myofibroblastic Tumor?
Jessica E. Sigel, MD, Tamara A. Smith, MD, John D. Reith, MD,
and John R. Goldblum, MD
Calcifying fibrous pseudotumor (CFT) is a rare benign soft tissue lesion composed
of dense hyalinized fibrous tissue containing bland spindle-shaped cells admixed
with a lymphoplasmacytic infiltrate and foci of dystrophic and often psammomatous
calcifications. It has been suggested that CFT represents a late sclerosing stage of
inflammatory myofibroblastic tumor (IMT). Recently, clonal cytogenetic abnormal-
ities involving the anaplastic lymphoma kinase (ALK) gene on chromosome 2p have
been identified in IMT, particularly those arising in deep soft tissue sites. We
evaluated seven cases of deep soft tissue CFT diagnosed at the Cleveland Clinic
Foundation and the University of Florida with available paraffin-embedded blocks
using a monoclonal antibody to ALK (Dako, Carpenteria, CA) and a modified
avidin-biotin complex method. The cohort included six women and one man with a
median age at diagnosis of 43 years (range, 26 to 67 years). Sites of CFT included
mesentery (3), peritoneum (1), omentum (1), serosa of small bowel (1), and anterior
mediastinum (1). Immunohistochemically, only one case showed focal staining for
ALK. The remaining six cases were negative, with appropriate positive and negative
control staining. In conclusion, unlike IMT, CFT in deep soft tissue locations rarely
expresses ALK by immunohistochemistry, suggesting that CFT is a different clini-
copathologic entity than IMT, as opposed to representing a “burned out” IMT.
Ann Diagn Pathol 5: 10-14, 2001. Copyright © 2001 by W.B. Saunders Company
Index Words: Calcifying fibrous pseudotumor, inflammatory myofibroblastic tumor,
anaplastic lymphoma kinase
C
ALCIFYING fibrous pseudotumor (CFT) is a
rare benign soft tissue lesion that primarily
affects deep soft tissue sites of children and young
adults.
1-14
Calcifying fibrous pseudotumor typically
presents as a well-circumscribed, nonencapsulated
lesion and is composed of a mixture of hyalinized
birefringent collagen, bland spindle-shaped cells, a
lymphoplasmacytic infiltrate, and dystrophic or
psammomatous calcifications.
The pathogenesis of this unusual lesion is un-
clear. While some believe CFT to be a reactive
rather than neoplastic process,
2
others have pro-
posed that CFT may represent a late sclerosing
stage of inflammatory myofibroblastic tumor
(IMT).
6,12
Recently, a subset of IMTs have been
shown to have clonal cytogenetic abnormalities in-
volving the anaplastic lymphoma kinase (ALK)
gene on chromosome 2p.
15-20
To further investigate the relationship between
CFT and IMT, we evaluated the immunohisto-
chemical expression of ALK in seven cases of deep
soft tissue CFT.
Materials and Methods
We searched the files of the Departments of
Anatomic Pathology of The Cleveland Clinic Foun-
dation (Cleveland, OH) and the University of Flor-
ida (Gainesville, FL) for cases of deep soft tissue
CFT. All available histologic slides were reviewed to
From the Department of Anatomic Pathology, The Cleveland Clinic
Foundation, Cleveland, OH; and the Department of Anatomic Pathol-
ogy, University of Florida, Gainesville, FL.
Address reprint requests to John R. Goldblum, MD, Cleveland Clinic
Foundation, 9500 Euclid Ave L25, Cleveland OH 44195.
Copyright
©
2001 by W.B. Saunders Company
1092-9134/01/0501-0002$35.00/0
doi:10.1053/adpa.2001.21474
10
Annals of Diagnostic Pathology,
Vol 5, No 1 (February), 2001: pp 10-14