Rhabdomyosarcoma arising in a giant congenital melanocytic nevus.

A number of lesions have been documented to arise within congenital melanocytic nevi (CMNs). Although the most frequent malignancy arising within a CMN is melanoma, the association between rhabdomyosarcoma and CMN has rarely been documented. We present a case arising in a 4-month-old girl with a giant CMN. She presented for evaluation of a pedunculated lesion at the superior gluteal crease that had been present since birth and exhibited rapid growth. Biopsy of the lesion revealed two distinct components: an expansile proliferation of pleomorphic cells with varying degrees of cellularity and a proliferation of banal-appearing melanocytic nevic cells. The cells of the expansile proliferation displayed a wide range of morphologic features, including nests of round cells, spindle-shaped cells, and more differentiated rhabdomyoblasts within a myxoid, highly vascularized stroma. Cross-striations, a marker of skeletal muscle differentiation, were present. These tumor cells were strongly immunoreactive with desmin, myo-D1, and myogenin. Fluorescence in situ hybridization analysis with PAX3/7-FKHR probes was negative. A diagnosis of embryonal rhabdomyosarcoma in association with CMN was made. Initial excision revealed tumor at the margins, and the patient underwent reexcision with subsequent chemotherapy with vincristine, actinomycin D, and cyclophosphamide. She was disease-free at the 6-year follow-up. It has been postulated that the combination of melanocytic and rhabdomyoblastic cells within the same lesion may imply derivation from a common pluripotent stem cell or neural crest cell. Clinicians following patients with giant CMN should consider rhabdomyosarcoma in the differential diagnosis of lesions arising within the nevus.

The use of intravenous palivizumab for treatment of persistent RSV infection in children with leukemia.

Palivizumab is a humanized monoclonal antibody used to decrease the threat of respiratory syncytial virus (RSV) infection among children at high risk. There are no standard guidelines due to conflicting data on palivizumab's use in the treatment of RSV lower respiratory tract infections. Intravenous (IV) palivizumab was shown to be well tolerated and associated with decreased mortality in high-risk children who have RSV disease. However, it did not prevent lower respiratory tract infections and did not affect the survival rate of allogeneic stem cell transplant recipients who had RSV infection. We present 2 children with acute lymphocytic leukemia (ALL) and persistent RSV infection while receiving chemotherapy. Patient A is a 4-year-old male with Down syndrome, ALL, and persistent RSV infection for at least 3 months. Patient B is a 3-year-old female with pre-B cell ALL whose chemotherapy intensification phase was delayed due to a month-long RSV infection. RSV infections were determined by using real-time polymerase chain reaction assays from nasopharyngeal swabs before IV palivizumab therapy; patient A was positive for RSV at 36 cycles and patient B was positive for RSV at 29 cycles. RSV infection was cleared in both patients within 72 hours after receiving IV palivizumab (patient A: 16 mg/kg; patient B: 15 mg/kg). IV palivizumab may be a treatment option for persistent RSV infection among immunocompromised patients.

Metastatic synovial sarcoma to the orbit.

Synovial sarcomas are rare malignancies. Metastatic synovial sarcomas carry a particularly poor prognosis. While primary orbital lesions have been documented, the authors are aware of only one previous report of metastatic synovial sarcoma to the orbit. In this report, the second case of a metastatic synovial sarcoma to the orbit is described and the medical literature on this subject is reviewed.