ARTICLE
A 50-year-old man presented with a large tumour on the left shoulder. The
lesion was present and slowly growing for ten years. Anamnesis did not reveal
any possible etiological factor or previous trauma. At the time of presentation,
the tumour measured 14 x 13 x 12 cm, superficial ulcerations were noted
but the lesion remained asymptomatic (Fig.
1). Both CT scanner and MRI described an exophytic mass without
signs of infiltration of the deepest structures. No enlarged lymph nodes
were noted on clinical examination or imaging. General screening was negative
for disseminated disease.
The lesion was completely removed by excisional surgery and the defect
was covered with a pedicled muscular pectoralis major flap associated
with split thickness grafts.
Clinical course of the patient and histological
findings
Adjuvant radiation therapy was administered because of the sarcomatous
component of the tumour and no recurrence occurred within a follow-up
period of one year.
Histological examination
The tumour presented a mixed histological pattern with areas of classical
dermatofibrosarcoma protuberans merging with more cellular, fascicular
areas (Fig. 3). Areas
of classical dermatofibrosarcoma protuberans were composed of uniform
spindle-shaped tumour cells with slender nuclei arranged in a storiform
growth pattern. A diffuse honeycomb infiltration into underlying fatty
tissue was seen. Higher grade areas were characterised by the presence
of an increased cellularity, a fascicular architecture in a herringbone
pattern, reminiscent of fibrosarcoma and an increased mitotic rate. The
underlying fascia was not invaded by the tumour. On immunohistochemistry,
CD34 staining was focally positive.
Fibrosarcomatous variant of dermatofibrosarcoma
protuberans
Discussion
The fibrosarcomatous variant of dermatofibrosarcoma protuberans is considered
as a rare lesion, probably less than 10% of all dermatofibrosarcoma protuberans
cases [1-5]. Fibrosarcomatous areas are characterised histologically by
long fascicles of spindle-shaped tumour cells with higher cellularity
and increased mitotic activity [1]. The presence of fibrosarcomatous areas
in dermatofibrosarcoma protuberans may raise additional problems in differential
diagnosis (fibrosarcoma, monomorphic synovial sarcoma...) [1-5]. However,
immunohistochemistry could help in differentiating the true dermatofibrosarcoma
protuberans with the fibrosarcomatous variant from classical dermatofibrosarcoma
protuberans or other tumors.
It is generally considered that "classical" dermatofibrosarcoma protuberans
is a low-grade tumour that is only locally aggressive and rarely metastasises.
However, a significantly higher rate of systemic metastases (up to 15%)
and/or tumour-related deaths was noted in association with the fibrosarcomatous
variant of dermatofibrosarcoma protuberans [1-5]. Moreover, a higher local
recurrence rate is associated with fibrosarcomatous dermatofibrosarcoma
protuberans, even after complete removal confirmed on histological examination
[4]. It should also be questioned if "classical" dermatofibrosarcoma protuberans
with metastases were not in fact fibrosarcomatous variant in which the
fibrosarcomatous areas were not clearly identified. This variant should
be regarded as a clinically significant progression from low-grade "classical"
dermatofibrosarcoma protuberans and should be considered as a fully malignant
soft tissue neoplasm.
What the exact signification concerning treatment modalities is remains
unclear from the literature but might provide a rational basis for a more
aggressive surgical treatment and certainly a close follow-up [1-5].
References
1. Mentzel T, Beham A, Katenkamp D, Dei Tos AD, Fletcher CDM.
Fibrosarcomatous ("high-grade") dermatofibrosarcoma protuberans. Clinicopathologic
and immunohistochemical study of a series of 41 cases with emphasis on
prognostic significance. Am J Surg Pathol 1998; 22: 576-87.
2. Connelly JH, Evans HL. Dermatofibrosarcoma protuberans. A
clinicopathologic review with emphasis on fibrosarcomatous areas. Am
J Surg Pathol 1992; 16: 921-5.
3. Ding J, Hashimoto H, Enjoji M. Dermatofibrosarcoma protuberans
with fibrosarcomatous areas. A clinicopathologic study of nine cases and
comparison with allied tumors. Cancer 1989; 64: 721-9.
4. Diaz-Cascajo C, Weyers W, Borrego L, Inarrea JB, Borghi S.
Dermatofibrosarcoma protuberans with fibrosarcomatous areas: a clinicopathologic
and immunohistochemic study in four cases. Am J Dermatopathol 1997;
19: 562-7.
5. Morimitsu Y, Hisaoka M, Okamoto S, Hashimoto H, Ushijima M.
Dermatobibrosarcoma protuberans and its fibrosarcomatous variant with
areas of myoid differentiation: a report of three cases. Histopathology
1998; 32: 547-51.
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