Sclerosing epithelioid fibrosarcoma
Sclerosing epithelioid fibrosarcoma is another rare, usually low-grade, sarcoma. It is typically treated with complete surgical excision.
Skeletal Muscle Tumors
There are three forms of rhabdomyosarcoma:
- Embryonal, plus subtypes of botryoid and spindle cells.
- Pleomorphic, also known as anaplastic sarcoma.
Refer to the PDQ summary on Childhood Rhabdomyosarcoma Treatment for more information.
Smooth Muscle Tumors
A 24-year retrospective analysis of the Italian cooperative group identified one child with leiomyosarcoma. A retrospective analysis of the St. Jude Children's Research Hospital (SJCRH) experience from 1962 to 1996 identified 40 children with nonrhabdomyosarcomatous STS; none had leiomyosarcoma. Among 43 children with HIV/AIDS who developed tumors, eight developed Epstein-Barr virus–associated leiomyosarcoma. Survivors of hereditary retinoblastoma have a statistically significant increased risk of developing leiomyosarcoma and 78% of these were diagnosed 30 or more years after the initial diagnosis of retinoblastoma.
So-called Fibrohistiocytic Tumors
So-called fibrohistiocytic tumors include the following tumor subtypes:
- Plexiform fibrohistiocytic tumor.
- Undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma.
- Giant cell.
- Myxoid/high-grade myxofibrosarcoma.
Plexiform fibrohistiocytic tumor
Plexiform histiocytic tumor is a rare, low- to intermediate-grade tumor that most commonly affects children and young adults. Depending on the series, the median age at presentation ranges from 8 to 14.5 years; however, the tumor has been described in patients as young as 3 months.[54,55]
The tumor commonly arises as a painless mass in the skin or subcutaneous tissue and most often involves the upper extremities, including the fingers, hand, and wrist.[56,57,58] There are rare reports of spread to regional lymph nodes or the lungs.[54,58,59]
No consistent chromosomal anomalies have been detected but a t(4;15)(q21;q15) has been reported.
Surgery is the treatment of choice but local recurrence has been reported in 12% to 50% of cases.
Undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma (high-grade)
At one time, malignant fibrous histiocytoma was the single most common histiotype among adults with STSs. Since it was first recognized in the early 1960s, malignant fibrous histiocytoma has been plagued by controversy in terms of both its histogenesis and its validity as a clinicopathologic entity. The latest World Health Organization classification no longer includes malignant fibrous histiocytoma as a distinct diagnostic category but rather as a subtype of an undifferentiated pleomorphic sarcoma.
This entity accounts for 2% to 6% of all childhood STSs. These tumors can arise in previously irradiated sites or as a second malignancy in patients with retinoblastoma.
These tumors occur mainly in the second decade of life. In a series of ten patients, the median age was 10 years and the tumor was most commonly located in the extremities. In this series, all tumors were localized and five of nine (for whom follow-up was available) were alive in first remission. In another series of 17 pediatric patients with malignant fibrous histiocytoma, the median age at diagnosis was 5 years and the extremities were involved in eight cases. All patients with metastatic disease died and two patients experienced a clinical response to a doxorubicin-based regimen.