Path Quiz Case-27: Diagnosis
Dermatofibrosarcoma protuberans is a fibrohistiocytic tumour of intermediate malignancy ,characterized by a distinctive storiform growth pattern and frequent local recurrences.
This tumour was first described in 1924 by Darier and Ferrand as 'progressive and recurring dermatofibroma'.
Over the years this tumour has been considered to be of fibroblastic, histiocytic and even of neural origin by different authors. Inview of the similarity of the tumour with benign fibrous histiocytoma, this tumour is tentatively classified with fibrohistiocytic tumours.
DFSP usually occurs in young and middle aged adults and is commonly located in the head and neck region followed by upper extremity . Palms and soles are not affected.
Cytogenetic analysis reveals reciprocal translocation t(17;22)(q22;q13)
and ring chromosome derived from translocation r(17;22).
- Dermal tumour which
extends into the subcutis where it infiltrates around small groups of fat
cells in a lacy or linear fashion.
FIBROSARCOMATOUS CHANGE IN DFSP:
Fibrosarcomatous change in DFSP represents a form of tumor progression in DFSP and is associated with a significantly more aggressive clinical course than in ordinary DFSP, indicating a possible need for treatment intensification in such cases.
Features include- There is increased cellularity and mitoses (more than 8 mitoses per 10 high power field).
Other features include focal myxoid change, keloid like hyalinization,
giant rosettes, pigmented melanocytes, myoid nodules and bundles.
MYXOID VARIANT OF DFSP:
Storiform pattern is less prominent. Blood vessels are
more conspicuous. Features supporting myxoid DFSP: (1) CD34:positive
Pattern of infiltration of the adipose tissue. (3) Genetic alterations:
ring / markers t(17;22)
This tumour is characterized
by combined features of dermatofibroma and DFSP. Features include-
-Giant cell fibroblastoma- Giant cell fibroblastoma: a report of three cases with histologic and immunohistochemical evidence of a relationship to dermatofibrosarcoma protuberans.Arch Pathol Lab Med. 1996 Nov;120(11):1052-5.
-Dermatofibroma- Dermatofibromas are small (often less than 1 cm), symmetrical and usually do not penetrate adipose tissue. Hemosiderin pigment is present. Tumour border is usually infiltrative but regular. Collagen is present at the peripheral border, in a keloidal pattern.There is birefringence of the collagen in dermatofibroma with polarization. Unlike DFSP, adnexal structures are not entrapped within the lesion. Heterogenous population of cells (histiocytes,fibroblasts or mixed).In DFSP, the cells are usually regular, small spindle shaped.
-Classic fibrosarcoma- Deep seated tumour. High mitotic index. The tumour rarely extends to the dermis
-Myxoid liposarcoma Presence of lipoblasts.
-Myxofibrosarcoma - Presence of pleomorphic cells.