History
4-year-old boy. Subcutaneous tumour of the left upper trunk.
Pathology
The lesion measures 2 cm in diameter and is made of a whitish,
rubbery tissue. It corresponds histologically to a non-encapsulated
proliferation of spindle-shaped fibroblast-like cells mixed
with bundles of collagen and some scattered multinucleated
giant cells. No atypia and no mitosis are reported. The lesion
extends to the resection margins. An immunohistochemistry staining
reveals a positivity of the proliferating cells for CD34, vimentin
and focally SMA. CD68 and protein S-100 are negative.
Discussion
GCF is an uncommon mesenchymal tumour of infancy
and childhood, especially localized in the superficial soft
tissues and was described in 1983 by Shmookler and Enzinger.
With a male predominance, it appears in children between age
2 to 18 and rare cases have been reported in adults. Generally
this painless lesion has been described in the trunk but 20%
of the cases can develop in the extremities. The lesion is
usually less then 5 cm and grows slowly. About 50% of pure
GCF recurs but not aggressively and generally not more than
once. Metastases have not been reported. Pure GCF may recur
as dermatofibrosarcoma protuberans (DFSP) or with prominent
areas of DFSP. Macroscopically it is represented
by an uncapsulated gray-white and often gelatinous mass with
myxoid foci without necrosis or hemorrhage.
Microscopically, the GCF is made of solid areas of
fusocellular stroma or wavy spindle cells with a moderate degree
of nuclear polymorphism and scattered giant cells. A characteristic
feature is the presence of pseudo-vascular spaces lined by
a discontinuous row of hyperchromatic giant cells. The lesion
infiltrates the deep dermis and subcutis and encircles adnexal
structures in a fashion similar to DFSP. The tumour may vary
in cellularity. The differential diagnosis must
be made with some vascular tumors, neurofibroma, myxoid sarcomas
and most important with DFSP. Important clues for the diagnosis
include superficial location, lack of intricate vasculature
and presence of multinucleated cells which lie along the pseudo
vascular spaces. GCF and DFSP show the same aspect in clinical
findings, anatomical distribution, morphology, ultrastructure
and immunohistochemistry.
Some studies have reported similarities between these two lesions.
Not only DFSP and GCF display the same immunohistochemistry and
particularly are positive for CD34 but areas of GCF may develop
in DFSP, DFSP may recur as GCF, GCF may contain foci of DFSP
or recur as DFSP. Moreover, DFSP and GCF share the same cytogenetic
abnormalities. More recently, a translocation (17; 22) (q22;
q13) has been described in both entities. These observations
suggest that both are closely related. The spatial and temporal
relations between the two tumours, their frequent expression
of CD34, the shared molecular defect and the presence of hybrid
lesions suggest a potential histogenetic relation hypothesized
as a common biologic process with varying morphologic expression.
Furthermore, the presence of ring chromosomes which are not observed
in childhood lesions as opposed to adult DFSP, could represent
a late event in the presumed multistep pathogenesis of DFSP.
