Ezrin and Moesin Expression Within the Developing Human Cerebrum and Tuberous Sclerosis-Associated Cortical Tubers.

The ERM (ezrin, radixin, and moesin) proteins belong to the band-4.1 superfamily of membrane-cytoskeleton-linking proteins which bind to the actin cytoskeleton via their C-terminal sequences and bind ERM binding membrane proteins (ERMBMPs). We investigated the immunohistochemical expression of two of the ERM proteins (ezrin and moesin) in developing human cerebral cortex and in cortical tubers from patients with tuberous sclerosis (TSC), to assess possible consequences of TSC gene product malfunction or inactivation in the developing brain in relation to ERM protein expression. Ezrin is abundantly expressed within radial glia and migrating cells in the intermediate zone in the prenatal human cerebrum, while moesin is primarily expressed in vascular endothelial cells in developing and adult human brain and scattered microglia in adult brain. In addition, both ezrin and moesin are abundantly co-expressed with hamartin and tuberin within a population of abnormal cells in TSC-associated cortical tubers. The expression of these two proteins--primarily ezrin--suggests that they are developmentally regulated and abundantly expressed in germinal matrix and/or migrating cells during cerebral cortical development. In TSC-associated cortical tubers, both proteins appeared to be up-regulated and are co-localized within a population of abnormal neuroglial cells typical of those seen in tubers. Expression of these proteins and their co-localization with tuberin and hamartin in these cells may suggest a compensatory up-regulation in response to TSC gene mutation

Intramedullary Amputation Neuromas Associated with Spinal Ependymomas.

We report 5 spinal intramedullary masses containing combined ependymoma and traumatic neuroma. The ependymomas, grade II cellular types, were intermixed with or separate from wavy, vaguely fascicular tissue that contained multiple axons immunoreactive for neurofilament protein. The neuromas presumably arose from small perivascular nerve twigs that have been implicated in the pathogenesis of intramedullary neuromas in non-neoplastic spinal diseases. Pathologists should be aware of this distinctive intramedullary tissue that is not to be confused with a neoplasm

Cytologic Diagnosis and Differential Diagnosis of Lung Carcinoid Tumors a Retrospective Study of 63 Cases with Histologic Correlation.

BACKGROUND:: Neuroendocrine (NE) neoplasms of the lung are a spectrum of tumors including typical carcinoid (TC), atypical carcinoid tumor (ACT), small cell lung carcinoma (SCLC), and large cell NE carcinoma (LCNEC). Given the overlapping features within these tumors, misclassification is a known risk, with significant treatment consequences. METHODS:: A search of the pathology archives from The Johns Hopkins Hospital yielded 390 cases of TC diagnosed over 20 years. Sixty-three cytology cases with corresponding surgical material were identified. The cytology specimens were comprised of 49 cases of lung fine-needle aspiriation specimens and 14 cases of lung brushings/washings. RESULTS:: Among 63 paired cases, 32 cases (51%) demonstrated concordant and 31 cases (49%) demonstrated discordant diagnoses. Among discordant cases, the most notable findings included overdiagnosis of TC as SCLC (4 cases; 6%), ACT (4 cases; 6%), and poorly differentiated carcinoma with NE features (5 cases; 8%) as well as misdiagnosis of other lesions as TC (4 cases; 6%) on cytology. CONCLUSIONS:: The significant morphologic factors for distinguishing low-grade TC from ACT, SCLC, or carcinoma remain the critical evaluation of nuclear features, chromatin patterns, and assessment of nucleoli. Nuclear molding and crowding are not discernible features because they may be found on smears with increased cellularity. Crush artifact can occur in both low-grade and high-grade NE neoplasms and may cause a misinterpretation of SCLC. Other artifacts resulting from delayed fixation or poor processing and sampling error are potential causes of incorrect interpretations. Ki-67 staining may be useful in difficult cases. Cancer (Cancer Cytopathol) 2010. © 2010 American Cancer Society