Abstract
Rhabdomyosarcoma is the most common soft tissue sarcoma in children and adolescents. Embryonal rhabdomyosarcoma (ERMS), its most common subtype, is a malignant soft tissue tumor with morphologic and immunophenotypic features of embryonic skeletal muscle. The histologic findings in ERMS typically include a range of differentiation in rhabdomyoblasts from primitive to terminally differentiated forms, and the latter become more prominent after chemotherapy-induced cytodifferentiation. Several reports have shown therapy-related cytodifferentiation to portend a good prognosis in ERMS. We discuss the case of a pediatric patient who presented with ERMS of the orbit. Although her tumor showed extensive posttreatment cytodifferentiation and several other good prognostic clinicopathologic factors, it pursued an aggressive course, resulting in early metastasis and death. This case represents an unusual course and may be instructive as to the clinicopathologic features impacting prognostication, and ultimately the biology, of this aggressive family of tumors.
Highlights
Maniraj Jeyaraju,1 Regina Ann Macatangay,2 Ashley Taylor-King Munchel,2 Teresa Anne York,2 Elizabeth A
The histologic findings in Embryonal rhabdomyosarcoma (ERMS) typically include a range of differentiation in rhabdomyoblasts from primitive to terminally differentiated forms, and the latter become more prominent after chemotherapy-induced cytodifferentiation
Several reports have shown therapy-related cytodifferentiation to portend a good prognosis in ERMS
Summary
A 4-year-old girl was brought to the pediatric emergency room with right eyelid swelling, tenderness, and pain with horizontal eye movement. The patient received salvage chemotherapy with vinorelbine, temsirolimus, and cyclophosphamide, but tumor size increased to 4:3 × 3:9 × 3:7 cm, prompting right maxillectomy and orbital exenteration; resection yielded negative margins and no lymph node involvement. She was treated postoperatively with 6 cycles of vincristine, cyclophosphamide, and topotecan; the family opted to stop therapy for increasing toxicity and no evidence of disease. A needle core biopsy of the mediastinal mass demonstrated sheets of primitive small round blue cells, numerous cells with prominent skeletal muscle differentiation, and frequent pleomorphic cells, with strong diffuse myogenin staining by immunohistochemistry, confirming the diagnosis of metastatic ERMS. Autopsy findings included a 20 cm mass in the left hemithorax, with left pleural involvement and encasement of the left lung, and numerous left lung and smaller right lung parenchymal metastases
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