Genetic markers of oral malignant melanoma analysed by fluorescence in situ hybridisation (FISH)

Abstract

Oral malignant melanoma (OMM) is a rare condition, and our knowledge about morphological and genetic modifications is scanty and incomplete. The aim of this study is to report morphological and fluorescent in situ hybridisation (FISH) data obtained in four cases of OMM. FISH results were also compared with those of cutaneous malignant melanoma (CMM, three cases), desmoplastic cutaneous melanoma (DMM, four cases) and spindle cells cutaneous melanoma (SCCM, one case). All the OMM cases showed a combined radial and vertical growth pattern, with the invasive component characterised by malignant spindle cells intermingled among collagen bundles. Two cases of OMM resulted positively stained with p16, in contrast with frequent loss of immunoreactivity in CMM. Three OMM were suitable for FISH analysis: 9p21 locus was deleted in 1/3, 1p36 resulted deleted 3/3, while EGFR gene showed a relative deletion. Similar genetic alterations were found in DMM and SCMM, but not in CMM. Ultrastructural findings further enhanced differences between OMM and CMM; OMM displayed, mature-staged melanosomes only within in situ component. In conclusion, OMM presents a morphological and genetic profile similar to DMM; and SCCM, however, displays some differences from CMM.

Immunohistochemical Expression of p16, p21, p27 and Cyclin D1 in Oral Nevi and Melanoma

“…In agreement with these results, cutaneous nevi have been shown to be uniformly positive for p16 in more than 70% of cells [7,15]. On the other hand, loss of p16 expression has also been demonstrated in almost 50% of primary cutaneous and oral melanomas, similarly to many other cancers, including pancreatic, esophageal, lung, head and neck, breast, bladder, brain and ovarian [1,5,13,14]. Although there is general consensus regarding the loss of p16 expression in cutaneous melanomas, it is suggested that this occurs in later stages of the disease, as it is not altered in melanoma in situ [16].…”

“…In this study, we evaluated the immunohistochemical expression of the cell cycle regulators p16, p21, p27, and cyclin D1 in 38 intramucosal nevi and 13 primary oral melanomas. There are no data on the immunohistochemical expression of these proteins in intramucosal nevi and only two reports considering p16 expression in oral melanomas [1,14]. The negative cell cycle regulators p16 and p27 were diffusely expressed at high levels in all intramucosal nevi cells, in contrast to oral melanomas, which demonstrated a much lower expression of these proteins.…”