Pigmented epithelioid melanocytoma: report of a case with favourable outcome after a 4-year follow-up period.

BACKGROUND: Pigmented epitheliod melanocytoma (PEM) is a uncommon melanocytoma with unique histopathological features and possibly with a favourable prognosis, because, although sentinel lymph-node metastases may occur, in the great majority of cases described up to now there is no spread beyond regional lymph-nodes. The nature of PEM, its biologic behaviour and its relationships to naevi and melanoma, however, remain to be clearly established, and several Authors suggest that further cases of PEM with long follow-up should be published, in order to better assess the biologic/prognostic characteristics of PEM. METHODS AND RESULTS: We report a new case of PEM, dealing with an oval, regularly marginated, darkly pigmented, asymptomatic nodule. The dermoscopic pattern showed a homogeneous blue-black pigmentation, without any other dermoscopic sign. The histopathologic analysis showed both isolated and nested oval melanocytes at the junctional level, and a mixture of epitheliod and spindle melanocytes, heavily pigmented, together with numerous melanophages in the dermis, with tendency to periadnexal distribution; cellular atypia was pronounced, but only occasional mitoses were identified in the superficial dermis. After a 4-year follow-up period after excision, no persistent lesion or metastases occurred. CONCLUSIONS: The present case suggests that PEM has a distinct histopathologic/diagnostic identity among melanocytic tumours. Although the up-to-now favourable outcome, however, our patient needs a large period of observation, and further studies with long follow-up are needed to better define the biologic/prognostic identity of PEM.

The vast majority of lymphocytes infiltrating primary cutaneous melanoma express the CD27 costimulatory receptor: implications for melanoma progression.

Melanoma progression is favoured by prevalence, within the micro-environment of primary cutaneous melanoma, of suppressive forces, e.g. exerted by CD4(+) CD25(+) FOXP3(+) regulatory T lymphocytes, over anti-melanoma immunity, e.g. exerted by CD8(+) cytolytic T lymphocytes. The CD27 glycoprotein is crucial because it is able to identify regulatory T cells endowed with strong suppressive ability, whilst CD8(+) T cells endowed with actual cytolytic ability become CD27(-). The present in situ quantitative immunohistochemical study, including a series of double labelling experiments and morphometrical cell analyses, shows that the vast majority of lymphocytes infiltrating primary cutaneous melanoma express CD27. Specifically, virtually the entire CD4(+) CD25(+) FOXP3(+) T subset infiltrating primary cutaneous melanoma also co-expressed CD27; CD27 was, moreover, co-expressed even by the vast majority of the CD8(+) T cells, and, conversely, effector/cytotoxic CD8(+)CD27(-) cells were very scarcely represented. The overwhelming CD27 co-expression may confer on the CD4(+)CD25(+)FOXP3(+) T subset a consistent capacity to suppress anti-melanoma immunity, whereas the too low CD8(+) CD27(-) cell proportion may presumably be insufficient to confer on the CD8(+) T subset a satisfactory anti-melanoma cytotoxic activity. We therefore propose that these CD27-discriminated pathways may trigger a functional imbalance within the microenvironment of primary cutaneous melanoma, thus favouring melanoma progression.