Trisomy 6 in Merkel cell carcinoma: a recurrent chromosomal aberration.
We retrospectively investigated 17 cases of primary and metastasizing Merkel cell carcinomas (MCC) from 14 patients using chromosomal in-situ hybridization (CISH) to study the occurrence of trisomy 6 in these lesions.


RESULTS
Histological diagnosis on all tumour samples was obtained on haematoxylin and eosin stained sections. Immunohistochemistry was performed with antibodies against pancytokeratin (CAM 5.2), cytokeratin 20 (CK20), MIC2 antigen (CD99), neuron-specific enolase (NSE), and chromogranin A (chrA). Sections (4 microm) of the paraffin-embedded tumours were analysed with alpha-satellite centromeric probes for chromosome 6 or 17 using CISH. The signal was amplified by the Tyramide Signal Amplification (TSA) assay. Immunohistochemically, the tumours showed the same general epithelial neuro-endocrine pattern: 11/13 expressed cytokeratin 20, and 47% exhibited trisomy 6, with no significant difference between primary and metastatic lesions. Incomplete follow-up data did not allow us to establish a prognostic value of trisomy 6, however, this aberration might be an additional diagnostic tool in distinguishing MCC from other small round blue cell tumours.


CONCLUSIONS
CISH seems to be a promising adjunctive method to diagnose Merkel cell carcinoma. Trisomy 6 should be investigated more closely in these cases, as has been done for chromosomes 1 and 11. Of particular interest would be identification of modifications in proto-oncogene(s) located on chromosome 6.
Gancberg
D
D
Department of Pathology, Institut Jules Bordet, Brussels, Belgium.
Feoli
F
F
Hamels
J
J
de Saint-Aubain
N
N
André
J
J
Rouas
G
G
Verhest
A
A
Larsimont
D
D
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D015266:Carcinoma, Merkel Cell / Q000737:chemistry / Q000235:genetics* / Q000556:secondary; D053379:Chromogranin A; D002864:Chromogranins / Q000032:analysis; D002896:Chromosomes, Human, Pair 6; D003582:Cytogenetics; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007381:Intermediate Filament Proteins / Q000032:analysis; D053554:Keratin-20; D007633:Keratins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010751:Phosphopyruvate Hydratase / Q000032:analysis; D000090063:Proto-Oncogene Mas; D012878:Skin Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D014314:Trisomy
D015415:Biomarkers; C400901:CAM 5.2 antigen; D053379:Chromogranin A; D002864:Chromogranins; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D007633:Keratins; D010751:Phosphopyruvate Hydratase