Massive Embryonal Rhabdomyosarcoma of the Hand in an Infant With Metastasis at Birth: Management Dilemma

Exceptional case of a hemangioma-like rabdomyosarcoma in the hand's palm

Rhabdomyosarcoma is a malignant tumor in children that might mimic a benign tumor, such as infantile hemangioma, particularly when detected early. Although rhabdomyosarcoma rarely occurs in the hand, its prognosis is generally poor, and successful treatment relies on a complete and radical surgical excision. We present a case of rhabdomyosarcoma located in the palm of an infant's hand, initially presenting clinical and radiological features suggestive of a vascular tumor. The resection of this mass was radical, and histological analysis and immunohistochemistry returned in favor of embryonic rhabdomyosarcoma. In similar cases recorded in the literature, the diagnosis may be first mistaken for that of a hemangioma, then confirmed by histology. This underlines the importance of a systematic anatomopathological examination of all tissues removed surgically.

Tongue orthotopic xenografts to study fusion-negative rhabdomyosarcoma invasion and metastasis in live animals

PAX3/7 fusion-negative rhabdomyosarcoma (FN-RMS) is a childhood mesodermal lineage malignancy with a poor prognosis for metastatic or relapsed cases. Limited understanding of advanced FN-RMS is partially attributed to the absence of sequential invasion and dissemination events and the challenge in studying cell behavior, using, for example, non-invasive intravital microscopy (IVM), in currently used xenograft models. Here, we developed an orthotopic tongue xenograft model of FN-RMS to study cell behavior and the molecular basis of invasion and metastasis using IVM. FN-RMS cells are retained in the tongue and invade locally into muscle mysial spaces and vascular lumen, with evidence of hematogenous dissemination to the lungs and lymphatic dissemination to lymph nodes. Using IVM of tongue xenografts reveals shifts in cellular phenotype, migration to blood and lymphatic vessels, and lymphatic intravasation. Insight from this model into tumor invasion and metastasis at the tissue, cellular, and subcellular level can guide new therapeutic avenues for advanced FN-RMS.

Fusion-negative rhabdomyosarcoma orthotopic tongue xenografts for study of invasion, intravasation and metastasis in live animals

PAX3/7 Fusion-negative rhabdomyosarcoma (FN-RMS) is a childhood mesodermal lineage malignancy with a poor prognosis for metastatic or relapsed cases. Towards achieving a more complete understanding of advanced FN-RMS, we developed an orthotopic tongue xenograft model for studies of molecular basis of FN-RMS invasion and metastasis. The behavior of FN-RMS cells injected into murine tongue was examined using in vivo bioluminescence imaging, non-invasive intravital microscopy (IVM), and histopathology and compared to the prevailing hindlimb intramuscular and subcutaneous xenografts. FN-RMS cells were retained in the tongue and invaded locally into muscle mysial spaces and vascular lumen. While evidence of hematogenous dissemination to the lungs occurred in tongue and intramuscular xenografts, evidence of local invasion and lymphatic dissemination to lymph nodes only occurred in tongue xenografts. IVM and RNA-seq of tongue xenografts reveal shifts in cellular phenotype and differentiation state in tongue xenografts. IVM also shows homing to blood and lymphatic vessels, lymphatic intravasation, and dynamic membrane protrusions. Based on these findings, the tongue orthotopic xenograft of FN-RMS is a valuable model for tumor progression studies at the tissue, cellular and subcellular levels providing insight into kinetics and molecular bases of tumor invasion and metastasis and, hence, new therapeutic avenues for advanced FN-RMS.

Embryonal rhabdomyosarcoma of the uterine cervix in an adult female

Embryonal rhabdomyosarcoma (RMS) of the female genital tract is an uncommon malignancy, presenting mainly in the pediatric and adolescent populations, primarily affecting the first two decades of life. This malignancy presentation in adulthood is rare and is seldom seen. The incidence of this tumor affecting adult females is approximately 0.4 - 1%, with the common site being the vagina. This tumor infrequently involves the cervix. RMS has a poor survival rate and once diagnosed, it requires aggressive management by radical surgery accompanied by chemoradiation. We present a case of an anaplastic variant of embryonal RMS of the uterine cervix presenting as a cervical polyp in a 36-year-old female who complained of dyspareunia and post-coital bleeding.