Figure 4
From: Mesothelioma with signet-ring cell features: report of 23 cases
(a) Signet-ring cell carcinoma of the lung in which the nuclei appear to have been displaced toward the periphery of the cell by large amounts of mucin. (b) Immunohistochemical preparation for keratin 7 in the same case showing strong reactivity throughout the cytoplasm. (c) Neoplastic cells in the same case showing strong nuclear positivity for TTF-1. (d) Hematoxylin-and-eosin-stained section of another case of signet-ring lung carcinoma in which many of the neoplastic cells appear to contain a large intracytoplasmic vacuole. (e) Immunohistochemical preparation for keratin 7 demonstrating that the large intracytoplasmic vacuoles seen on hematoxylin-and-eosin stain most likely represent intracytoplasmic lumina. (f) Immunostaining for napsin A showing granular positivity mostly at the periphery of the neoplastic cells.
