|
Advertisement |
|
|
||
 |
|
|||||
|
|||||
|
 |
||||||
|
||||||
|
||||||
|
Journal of Clinical Oncology, Vol 23, No 21 (July 20), 2005: pp. 4790-4791 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.06.037
Pediatric MalignanciesCASE 1. Hypermethylation in Orbital Alveolar RhabdomyosarcomaDepartment of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Hong Kong, People's Republic of China
Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong, People's Republic of China
Department of Ophthalmology and Visual Sciences; Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Hong Kong, People's Republic of China
Department of Ophthalmology and Visual Sciences, Prince of Wales Hospital, Hong Kong, People's Republic of China A 10-month-old boy, born full term in Hong Kong, presented with increasing right-eye proptosis for 2 months. The parents had noted a concomitant right lower eyelid coin-sized swelling with violaceous skin discoloration. It was managed as a lower eyelid chalazion by several ophthalmologists initially with oral antibiotic treatment and then incision and curettage. The procedure, however, drained no pus, and computed tomography (CT) of orbit showed a huge contrast-enhancing soft tissue mass infiltrating the right inferior rectus muscle. On referral, a 2 x 2 cm solitary right lower lid, firm to hard, nontender mass could be palpated. There was no fluctuance and it was not possible to get behind the mass. No tethering to surrounding tarsus could be demonstrated. The right proptosis was nonaxial with upward displacement of the globe. Both the depression and elevation of the right globe were restricted. The intraocular pressure and fundal examination of both eyes were normal. No cervical lymphadenopathy could be palpated. Systemic review was unremarkable and no important neonatal or family history was noted. Magnetic resonance imaging of orbit confirmed the presence of a 3 x 2.7 x 3-cm tumor mass, which arose predominantly from inferior rectus muscle, extending into the right retrobulbar region (Fig 1). The signal density was heterogeneous, suggestive of internal necrosis. The optic nerve had been displaced by tumor but neither invasion nor compression were seen. The optic foramen was not widened. Both the medial wall and floor of orbit appeared to be invaded, whereas the lateral wall and orbital roof stayed clear. The tumor was abutting the medial rectus, but there was no sign of invasion. Other extraocular muscles and pterygopalatine fossa were spared. No intracranial extension could be seen. A transconjunctival incisional biopsy under general anesthesia was arranged in liaison with neonatologist and anaesthesiologist. Histopathologic examination revealed clusters and sheets of tumor cells of polygonal to spindle shape with nuclear pleomorphism, stippled chromatin, distinct nucleoli, and eosinophilic cytoplasm among the fibrous stroma diagnostic of rhabdomyosarcoma (Fig 2). The tumor cells exhibited strong and diffuse positive staining for desmin and myogenin by immunohistology analysis, whereas other immunomarkers were negative (Fig 3). We also carried out molecular hypermethylation profiling of 27 genes that frequently show hypermethylation in human cancers (Fig 4). Methylation-specific polymerase chain reaction (PCR) analyses of DNA from alveolar rhabdomyosarcoma tumor demonstrated that existence of PCR products in lane M indicates the presence of methylated alleles, and in lane U unmethylated alleles. Four of twenty-seven genes were methylation positive (RB1, HIC1, HIN-1, and CDX-1), and the rest were methylation negative. Representative example of negative control (water) and positive control (CTL) for COX2 was shown. The analysis included well-characterized tumor suppressor genes, DNA repair genes, and genes related to metastasis and invasion.1, 2 Among them, promoter hypermethylation was identified in only four tumor suppressor genes: HIC1, HIN-1, RB1, and CDX-1. It is notable that there was no detectable promoter hypermethylation for the myogenic marker MyoD1. A whole-body CT staging consisting of CT of brain, neck, thorax and abdomen was performed and showed absence of metastases. Bone marrow examination and bone scan were negative for neoplastic infiltration. CBCs, biochemical profiles, clotting, and serum immunoglobulins were all normal. The right orbital alveolar rhabdomyosarcoma was categorized as group 3, stage I, T1a, N0 and M0 disease. Chemotherapy in accordance with the International Rhabdomyosarcoma Study (IRS) with the VAC regimen (vincristine, 0.025 mg/kg; dactinomycin, 0.025 mg/kg; and cyclophosphamide, 36 mg/kg) for 40 weeks was initiated. In addition, right transconjunctival debulking surgery of the inferior rectus tumor was performed, followed by local external beam radiotherapy. Both the systemic and ocular conditions of the patient were stabilized.
Histologic subcharacterization of rhabdomyosarcoma occasionally can be difficult. Immunohistochemistry can aid diagnosis. Alteration in genomic DNA methylation, associated with the transcriptional repression of cancer-associated genes, is an important mechanism in the pathogenesis of human cancers.1 Identification of DNA hypermethylation is an efficient approach for detection of disease-associated genes and identification of molecular markers with prognostic significance in cancers.3 In our screening for promoter hypermethylation in this patient, three tumor suppressor genes (HIN-1, RB1, and CDX-1) were identified for the first time to be hypermethylated in alveolar rhabdomyosarcoma. The potential use of epigenetic profiling as a molecular marker to distinguish rhabdomyosarcoma subclasses, was evidenced by preferential hypermethylation of MyoD1 in embryonal rhabdomyosarcoma (10 of 11; 91%)4 and HIC1 hypermethylation in alveolar rhabdomyosarcoma (eight of eight; 100%).5 There is thus good evidence for concordance between differential methylation status of HIC1 and MyoD1 and histologic subtypes (embryonal and alveolar rhabdomyosarcoma), as illustrated by the presence of hypermethylated HIC-1 and the absence of MyoD1 methylation in our alveolar rhabdomyosarcoma patient. The roles of HIN-1, RB1, and CDX-1 hypermethylation in alveolar rhabdomyosarcoma pathogenesis remained unclear and need further elucidation, although it is noted that a characteristic t(2;13) translocation with the break point localized on 13q14 near RB1 has been documented in alveolar rhabdomyosarcoma.6 Studies with larger sample size are warranted to ascertain the nature of this epigenetic phenomenon. Authors' Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest.
REFERENCES 1. Chen B, Dias P, Jenkins JJ III, et al: Methylation alterations of the MyoD1 upstream region are predictive of subclassification of human rhabdomyosarcomas. Am J Pathol 52:1071-1079, 1998
2. Rathi A, Virmani AK, Harada K, et al: Aberrant methylation of the HIC1 promoter is a frequent event in specific pediatric neoplasms. Clin Cancer Res 9:3674-3678, 2003 3. Baylin SB, Herman JG, Graff JR, et al: Alterations in DNA methylation: A fundamental aspect of neoplasia. Adv Cancer Re 72:141-196, 1998
4. Ward RL, Cheong K, Ku SL, et al: Adverse prognostic effect of methylation in colorectal cancer is reversed by microsatellite instability. J Clin Oncol 15; 21:3729-3736, 2003
5. Kopelovich L, Crowell JA, Fay JR: The epigenome as a target for cancer chemoprevention. J Natl Cancer Inst 95:1747-1757, 2003
6. Wang-Wuu S, Soukup S, Ballard E, et al: Chromosomal analysis of sixteen human rhabdomyosarcomas. Cancer Res 48:983-987, 1988
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|||||||||||
|
|||||||||||
|
|
Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
|
