Changes on chromosome 11p15.5 as specific marker for embryonal rhabdomyosarcoma?

Rhabdomyosarcomas (RMS) constitute a heterogeneous spectrum of tumors with respect to clinical behavior and tumor morphology. The paternal uniparental disomy (pUPD) of 11p15.5 is a molecular change described mainly in embryonal RMS. In addition to LOH, UPD, the MLPA technique (ME030kit) also determines copy number variants and methylation of H19 and KCNQ1OT1 genes, which have not been systematically investigated in RMS. All 127 RMS tumors were divided by histology and PAX status into four groups, pleomorphic histology (n = 2); alveolar RMS PAX fusion-positive (PAX+; n = 39); embryonal RMS (n = 70) and fusion-negative RMS with alveolar pattern (PAX-RMS-AP; n = 16). The following changes were detected; negative (n = 21), pUPD (n = 75), gain of paternal allele (n = 9), loss of maternal allele (n = 9), hypermethylation of H19 (n = 6), hypomethylation of KCNQ1OT1 (n = 6), and deletion of CDKN1C (n = 1). We have shown no difference in the frequency of pUPD 11p15.5 in all groups. Thus, we have proven that changes in the 11p15.5 are not only specific to the embryonal RMS (ERMS), but are often also present in alveolar RMS (ARMS). We have found changes that have not yet been described in RMS. We also demonstrated new potential diagnostic markers for ERMS (paternal duplication and UPD of whole chromosome 11) and for ARMS PAX+ (hypomethylation KCNQ1OT1).

Alveolar type of rhabdomyosarcoma of maxilla-A case report.

Rhabdomyosarcoma (RMS) is the most common sarcoma among children and accounts for 20% of soft tissue sarcomas. In children, close to 50% of rhabdomyosarcomas arise in the head and neck. RMS of the oral cavity is rare and is seen in only 10-12% of all head and neck lesions and the involvement of the jaws is extremely rare. Histopathologically, the various types are pleomorphic type, botryoid type, spindle cell type, embryonal, and alveolar type of RMS. The alveolar variant accounts for almost 30% of all rhabdomyosarcomas and tends to arise in patients of the age group 10-25 years. We present a case of orofacial RMS in a young adult who was referred to our Institution for the management of an odontogenic lesion of the maxilla. The clinicopathological aspects and poor survival rate as a consequence of delayed diagnosis are discussed. We dentists may misdiagnose it as an odontogenic tumour due to its location in the oral and maxillofacial region. Careful clinical history and examination and investigations may help to narrow down the diagnosis. Expert opinion and referrals to oral pathologists and oncologists are essential to arrive at early diagnosis and to initiate the treatment.