Dermatofibrosarcoma protuberans (DFSP) is also known as progressive, recurrent dermatofibrosarcoma. The tumor has a high recurrence rate (20%-50%) but rarely metastasizes. It is predominantly seen in adults; it is more common in males than females; and it develops on the trunk. It is often associated with high CD34 expression;

Rhabdomyolysis cutaneous fibrosarcoma has a variety of morphologies, and the common ones include classic rhabdomyolysis cutaneous fibrosarcoma, pigmented rhabdomyolysis cutaneous fibrosarcoma, mucinous rhabdomyolysis cutaneous fibrosarcoma, rhabdomyolysis cutaneous fibrosarcoma with myxoid differentiation, plaque-like rhabdomyolysis cutaneous fibrosarcoma, and fibrosarcomatous rhabdomyolysis cutaneous fibrosarcoma. Especially in some rare subtypes (e.g., atrophic, plaque-like) subtypes, histologic diagnosis is difficult, and FISH probes can be a good aid to diagnosis;

Characteristic molecular genetic alteration of rhabdomyosarcoma and the closely related giant cell fibroblastoma: the presence of a large number of ring chromosomes formed by chromosome 17/22 forming the COL1A1-PDGFB fusion gene, an alteration that has not been detected in any other sarcoma.COL1A1-PDGFB gene fusion (t(17;22)(q21;q13)) It is most commonly seen in adults and has a high rate of recurrence after surgery. A large body of literature showed that 178 of 185 cases of confirmed pilonidal mutations were FISH-positive, 91% (104/114) of suspected cases (probable) were FISH-positive, and 81% (91/112) of possible cases (probable) were FISH-positive;

The COL1A1-PDGFB fusion gene is also seen in giant cell fibroblastoma, which supports the notion that giant cell fibroblastoma is the juvenile form of rhabdomyosarcoma;

Fibrosarcoma-type rhabdomyosarcoma is classified as malignant in the 2013 edition of the WHO classification (ICD-3).