Fig. 2

a Pathological section biopsy showing infiltration by lung adenocarcinoma cells with acinar and papillary mixed type (hematoxylin and eosin staining 100 x); b Pathological section biopsy showing infiltration by solid short fusiform epithelioid cell nests containing melanin pigmentation from the lung lesion (100x); c Immunohistochemical expression of HMB-45 in neoplastic cells (DAB, magnification 100x). d Immunohistochemical expression of Ki-67 in neoplastic cells (DAB, magnification 100x)