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Sclerosing epithelioid
fibrosarcoma
is a
rare variant of fibrosarcoma,
originally described in 1995 by Meis-Kindblom et al.
The tumour occurs in young and middle aged adults.
Most examples arise in
the deep skeletal muscles of adults.
In rare cases
the tumour may arise along the neuraxis. These tumours may demonstrate
aggressive clinical behavior, compared to those arising in the more
typical location of deep skeletal muscles.
Sclerosing
epithelioid fibrosarcoma can also occur as a primary tumour in
the bone.
Common sites include lower limb, limb girdle, head and neck region, back
or chest wall.
Despite the relatively
bland appearance and low mitotic activity, the tumour is capable of local
recurrence and distant metastasis often several years after surgical
removal.
Macroscopically, the tumours are usually less than 10 cm in diameter and
presents as well circumscribed, lobulated masses.
Microscopic
features:
Image1
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Histologically, the tumour is hypocellular with
prominent areas of stromal hyalinization.
The hyaline stroma may be mistaken for osteoid.
The cellular areas are characterized by small to medium-sized round to ovoid,
relatively uniform, bland cells, often
with clear cytoplasm, arranged in cords and strands,
embedded in the hyalinized
fibrous stroma.
In some areas, nests,
sheets, acini or alveolar structures are also noted.
The mitotic count is
usually less than 1 per 10 high power fields.
In some cases the tumour
may exhibit large areas of necrosis together with areas of high
grade nuclear anaplasia and active mitosis.
Immunohistochemistry:
Vimentin
- diffuse and strong
positivity.
EMA
-
focal or weak
positivity . Tumour cells are negative for
CAM5.2 , AE1/AE3, S100
protein, HMB45, desmin, alpha-smooth muscle actin, CD34 and LCA.
Differential diagnosis
:
Metastatic carcinoma ;
Hyalinised leiomyoma
;
Sclerosing lymphoma ;
Fibromatosis
;
Nodular fasciitis;
Benign fibrous histiocytomas
;
Ossifying fibromyxoid tumours ;
Clear cell sarcomas ;
Epithelioid sarcomas;
Synovial sarcomas ;
Extraskeletal osteosarcomas ;
Extra-skeletal
myxoid chondrosarcoma.
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