High-grade pleomorphic rhabdomyosarcoma in a 60-year-old male: a case report and review of the literature

Rhabdomyosarcoma in a Rabbit

A geriatric Holland Lop rabbit presented for acute lameness. A pathologic fracture of the right distal femur associated with a pleomorphic rhabdomyosarcoma was diagnosed, and staging radiographs showed no overt metastasis upon initial presentation. The limb was amputated and submitted for microscopic examination. Immunohistochemical evaluation revealed the neoplastic cells were positive for desmin and MyoD1, and negative for cytokeratin AE1/AE3, CD204, IBA-1, and SMA. Gross, histologic, and immunohistochemical evaluation confirmed a diagnosis of pleomorphic rhabdomyosarcoma. The patient died 396 days after amputation, and a post-mortem examination showed metastatic sarcoma to multiple organs.

Incidental Discovery of Embryonal Rhabdomyosarcoma on CT Imaging

Rhabdomyosarcoma is an uncommon soft tissue sarcoma that rarely presents in adults. Clinical presentation is dependent on site and size. We present the case of a woman who presented with acute-onset dyspnoea and whose pathology report confirmed embryonal rhabdomyosarcoma (ERMS) seen as an incidental finding on chest computed tomography. We also describe the clinical, laboratory and radiological work-up conducted to diagnose and manage ERMS in the critical care setting.

LEARNING POINTS

Rhabdomyosarcoma is a rare malignancy with a poor prognosis in adults compared with children, especially if it presents in an unfavourable primary site and has an unfavourable histological diagnosis.Immunohistochemical diagnosis remains the gold standard for embryonal rhabdomyosarcoma diagnosis and differentiation from similar malignancies on initial imaging studies.Management of adult rhabdomyosarcoma is usually multimodal with surgical resection and a combination of chemo and radiotherapy.

Molecular analysis of 10 pleomorphic rhabdomyosarcomas reveals potential prognostic markers and druggable targets

Pleomorphic rhabdomyosarcoma (PRMS) is a rare and aggressive adult sarcoma with a median overall survival of less than 2 years. Most PRMS do not respond to conventional chemotherapy and/or radiation, and targeted therapies are nonexistent as few PRMS have undergone the molecular characterization necessary to identify therapeutic options. To date, complex structural and few recurrent regional copy alterations have been reported in the PRMS cases evaluated by cytogenetic and comparative genomic hybridization. Thus, there remains an urgent need for more comprehensive molecular profiling to both understand disease pathogenesis and to identify potentially actionable targets. Ten PRMS resection cases were retrieved from institutional archives and clinicopathologic demographics were recorded. All tumors were subjected to DNA-based targeted next-generation sequencing (NGS) of 340 cancer-related genes while a subset (six cases) underwent gene-expression profiling of 770 genes. Alterations identified by NGS included genes involved in cell cycle regulation (90%), the RAS/MAPK and AKT pathways (80%), telomere maintenance (40%), chromatin remodeling (40%), and DNA repair (20%), as well as the cAMP-signaling pathway (10%). Microsatellite instability was absent in all cases, and tumor mutational burden was predominantly low. Gene expression profiling revealed up-regulation of many of the same pathways, including the RTK/MAPK, AKT/PIK3CA/mTOR, Wnt, Hedgehog and JAK/STAT pathways. Survival analysis demonstrated patients with concurrent biallelic inactivation of CDKN2A and TP53 showed significantly shorter overall survival (median: 2 vs. 50 months). Our integrated molecular characterization identified not only potentially targetable alterations, but also prognostic markers for stratification of PRMS patients.