Nuclear pseudoinclusions in melanoma cells: prognostic fact or artifact? The possible role of Golgi phosphoprotein 3 overexpression in nuclear pseudoinclusions generation.

Nuclear pseudoinclusions (NPIs) are classically found in papillary thyroid carcinoma and meningioma. Although NPIs have been described in melanocytic lesions, there is no systematic analysis of potential relationship between NPIs and other clinicopathological characteristics of melanoma. We examined the presence of NPIs in H&E-stained tissue sections form 96 melanomas and analyzed statistical associations with important clinicopathological parameters and tissue immunoreactivity for selected proteins involved in epithelial-mesenchymal transition (SPARC, N-cadherin), cell adhesion and mobility (ALCAM, ADAM-10), regulation of mitosis (PLK1), cell survival (FOXP1) and functioning of Golgi apparatus (GOLPH3, GP73). NPIs were observed in 20% of melanomas and their presence correlated with high mitotic rate and ulceration of the tumor, but not with Breslow thickness, histologic type, or presence of metastases. We observed a significant correlation with shorter cancer-specific survival, but not disease-free survival. Presence of NPIs was related to high expression of GOLPH3 in melanoma cells, whereas their absence was linked to enhanced immunoreactivity of GOLPH3 in tumor-associated macrophages. NPIs are not an uncommon finding in skin melanoma and their diagnostic and prognostic utility could be helpful in the daily routine histopathological practice. The possible explanation of NPI generation is associated with enhanced activity of Golgi apparatus in melanoma cells.