Case Seven – July 2017
- 32 year old female presented with a firm, non-mobile subcutaneous nodule on her abdomen
- Dermatofibroma
- Dermatofibrosarcoma protuberans
- Lipoma
Sections show a cellular spindle cell proliferation based within the deep dermis and subcutaneous tissue.
The tumor is composed of monomorphic, hyperchromatic spindle cells with a storiform growth pattern.
The lesion infiltrates diffusely through the subcutaneous tissue and entraps individual adipocytes leading to a characteristic honeycomb pattern.
The tumor is strongly positive for CD34 immunohistochemical stain.
Dermatofibrosarcoma protuberans
- Dermatofibrosarcoma protuberans, DFSP, is a malignant fibrohistiocytic neoplasm based within the dermis or subcutaneous tissue
- It most commonly presents as a slow growing, firm, non-mobile subcutaneous nodule on the trunk of adults in their third to fifth decade of life
- Histology shows a cellular, monomorphic spindle cell neoplasm with a storiform growth pattern and characteristic honeycomb pattern of invasion within the subcutaneous tissue
- Admixed inflammatory cells and histiocytes (including foam cells) are rare
- The main histologic differential diagnosis includes dermatofibroma, DF
- DF is less cellular and has admixed inflammatory cells/histiocytes
- DF shows a less infiltrative growth pattern, typically without significant invasion of the subcutaneous tissue
- DFSP is strongly positive for CD34 immunohistochemical stain
- Dermatofibroma is negative for CD34 negative and positive for FactorXIIIa
- Almost all DFSPs harbor a t(17,22)(q21;q13) translocation involving the collagen type 1 alpha 1 gene and platelet derived growth factor beta chain gene
- Giant cell fibroblastoma is the juvenile counterpart of DFSP which shares the same translocation
- Fibrosarcomatous transformation from conventional DFSP can occur and is characterized by loss of CD34 expression
- Bednar tumor is a rare variant of DFSP containing S-100+ pigmented dendritic cells
- DFSP can be locally aggressive and recur but rarely metastasizes
- Wide local excision is the treatment of choice
- Dermatofibrosarcoma protuberans, DFSP, is a malignant fibrohistiocytic neoplasm that often presents as a slow growing, non-mobile subcutaneous nodule on the trunk
- DFSP is strongly positive for CD34 immunohistochemical stain and shows a characteristic honeycomb pattern of invasion within the subcutaneous tissue
- Almost all DFSPs harbor a t(17,22)(q21;q13) translocation involving the collagen type 1 alpha 1 gene and platelet derived growth factor beta chain gene
- DFSP can be locally aggressive and recur but rarely metastasizes
- Wide local excision is the treatment of choice