Primary signet-ring cell/histiocytoid carcinoma of the eyelid: a clinicopathologic study of 5 cases and review of the literature.

Primary cutaneous signet-ring cell carcinomas are rare and aggressive neoplasms. These neoplasms have been mostly described in the eyelids, and more uncommonly, in the axillary skin. Histopathologically, the neoplasm seems to be composed of signet-ring cells or histiocytoid epithelial cells arranged in an Indian file growth pattern between collagen bundles of the dermis.

The hypointense liver lesion on T2-weighted MR images and what it means.

The vast majority of focal liver lesions are hyperintense on T2-weighted magnetic resonance (MR) images. Rarely, however, hepatic nodules may appear totally or partially hypointense on those images. Causes for this uncommon appearance include deposition of iron, calcium, or copper and are related to the presence of blood degradation products, macromolecules, coagulative necrosis, and other conditions.