C. Brathwaite et S. Suster, DERMATOFIBROSARCOMA PROTUBERANS - A CRITICAL REAPPRAISAL OF THE ROLE OF IMMUNOHISTOCHEMICAL STAINS FOR DIAGNOSIS, Applied immunohistochemistry, 2(1), 1994, pp. 36-41
An immunohistochemical study of 14 cases of dermatofibrosarcoma protub
erans in routinely processed formalin-fixed, paraffin-embedded tissues
was performed using a panel of antibodies, including muscle-specific
actin (HHF35), alpha-smooth-muscle actin, desmin, vimentin, cytokerati
n cocktail, myelin basic protein, epithelial membrane antigen, KP-1 (C
D68), anti-melanoma-specific antigen (HMB-45), S-100 protein, collagen
type IV, and the anti-HPCA-1 hematopoietic progenitor cell antibody (
CD34). Staining for actin and collagen type IV expression was limited
to perivascular areas, but no staining could be observed in the prolif
erating spindle cells. Myelin basic protein reactivity was limited to
the perineurium of entrapped nerves; some faint focal positivity was a
lso observed in many of the spindle cells forming the tumor, but this
was interpreted as nonspecific reactivity. S-100 protein stains were n
egative throughout the lesion; however, focal scattered S-100 protein-
positive dendritic cells were observed in one case. Stains for epithel
ial membrane antigen, desmin, cytokeratin, KP-1, and HMB-45 were unifo
rmly negative in all cases studied. Vimentin showed strong immunoreact
ivity in the spindle cells in all cases. Seven of the 14 cases showed
strong immunoreactivity with anti-HPCA-1 (CD34); however, this antibod
y also stained scattered fibroblastic cells outside the tumor, and foc
al positivity could also be obtained in dermal fibroblasts in the cont
rols. The findings support the fibroblastic nature of these tumors and
provide no convincing evidence to support neural or myofibroblastic d
ifferentiation. Contrary to recent claims in the literature, the CD34
immunoreactivity observed in these neoplasms is most likely nonspecifi
c rather than representing a sensitive or specific marker for dermatof
ibrosarcoma protuberans. The diagnosis of DFSP remains largely depende
nt on the recognition of its characteristic light microscopic features
and the role of immunostains is still limited, for the time being, to
ruling out alternate diagnoses.