Low-grade sarcoma of fibroblast origin with an incidence of 0.8 cases per million persons per year.
The most common dermal sarcoma and accounts for approximately 18% of all cutaneous soft tissue sarcomas.
Characterized by slow-growing, insidious, locally aggressive cutaneous tumor with a high rate of local recurrence but a low risk of metastases, and histologically by infiltrative cart wheel pattern fascicles of uniform bland spindle cells with diffuse CD4 expression.
Spindle cells are positive for CD34, hyaluronate, vomentin, and negative for factor XIIIa, S 100, desmin, CD68, and smooth muscle actin.
Usually present is as asymptomatic papule or indurated patch.
The process grows slowly and goes unrecognized for years.
Color is variable from erythematous, pink, brown, blue-ish, gray, or flesh color.
Lesions may have surface or marginal telangiectasia.
The lesion is usually adhered to the overlying skin, but not to the underlying structures.
Fixation to underlying structures may indicate late disease.
At the time of diagnosis the lesion usually majors 1-5 cm.
With late diagnosis the lesion may enlarge and protrude through the skin, providing the name protuberans.
Lesion predilection is the trunk with 40 to 50% of lesions, proximal extremities with 30 to 40%, and head and neck lesions 10 to 15%.
Atypically the lesions may involve the breast, the vulva, pubic area, and scalp.
In children the most common sites of involvement or the back and the extremities.
Atypia and mitotic activity are usually minimal or absent.
Estimated incidence is between 0.8 and 5 cases per million individuals per year.
Slight male predominance in adults.
Slight female predominance in the pediatric age group.
Occurs in all age groups, even in congenital situations.
Approximately 6% of cases occur in pediatric age group.
The process is more common among blacks than among whites.
Trauma implicated as a possible etiologic factor, but lacks convincing evidence.
Rarely associated with metastases.
Development of regional or distant metastases only 1% and 4%, respectively.
Local recurrence of 0-60%.
Greater than 90% of cases exhibit reciprocal chromosomal translocation t(17; 22) (q22;q13) and supernumerary ring chromosomes composed of interspersed sequences from 17q22 and 22q12.
The above translocation results in the fusion of collagen type I alpha-1 chain disease (COL1A1) on chromosome 17 with the platelet-derived growth factor B gene on chromosome 22.
The fusion protein COL1A1-PDGFB activates PDGF receptor, leading to its activation and subsequent tumor formation.
In approximately 8% of cases genes located on the chromosomes have been shown to be responsible for the tumor formation.
Rare, slow-growing, painless tumor that arises in the dermis.
Typically occurs in people 20-40 years of age.
With time invades underlying fascia, muscle and bone.
Local recurrence after wide excision for trunk lesions 0-21%.
Lesions originating in the head and site have high-rate of local recurrences in the range of 50-75%.
5-year disease free rates for head and neck lesions treated with wide excision are 25-50%.
5-year disease free rates for trunk lesions treated with wide excision are 80-100%.
Treatment with Mohs surgery results in more favorable outcomes and less trauma and sacrifice of adjacent normal tissue than treatment with wide excision.
With Mohs surgery about 7% will have a local recurrence.
After wide excision 80% of those who recur will do so by 5 years.
All patients must be followed for life for late recurrences after surgery.
May respond to imatinib.
10-15% of tumors are of head and neck origin.