Calderó, Sònia Gatius

In keeping with the stated goal of providing the surgical pathologist with tools to recognize abnormalities of the gastrointestinal (GI) tract due to drugs (AGIDS), in part II of this review we embark in a more organ-based description of AGIDS. Adequate space is given to the numerous adverse gastrointestinal effects of nonsteroidal anti-inflammatory drugs. Pill esophagitis, esophagitis dissecans, proton pump inhibitors’ effects, diaphragm disease, and the recently described effects of drugs such as olmesartan, mycophenolate, and of compounds such as yttrium-90 are highlighted among several others. The inclusion of drug effects in the differential diagnosis of “conventional” diseases (such as gastric antral vascular ectasia, graft-versus-host disease, ischemic colitis, acute colitis, collagenous enteritis, inflammatory bowel disease) is underscored to avoid sometimes significant diagnostic pitfalls. We reiterate the message of the necessary collaboration between pathologist and clinician in the recognition of these entities to provide the best patient care.

Abnormalities of the gastrointestinal (GI) tract due to drugs (AGIDs) are numerous and have significant impact. The aim of this narrative review is to help the practicing surgical pathologist recognize selected AGIDs. The adverse drug effects presented were chosen with an emphasis on recent and significant pathological and clinical contributions. The selection was based on a thorough review of the PUBMED-based literature and on the authors’ opinions and experience. In the first part of the review, diagnostic abnormalities due to crystals (eg, iron, biphosphonates, nonsystemic drugs), mitosis arresting drugs (colchicine, taxanes), and biological agents, especially ipilimumab, are discussed. Some AGIDs’ histopathologic features can be easily recognized. It is however the clinical correlation that in many cases of AGIDs will provide the necessary support for a drug effect diagnosis. The identification of AGIDs requires heightened awareness of the medical team in which close collaboration of pathologists and clinicians cannot be overemphasized.

BACKGROUNDThe cytological diagnosis of malignant mesothelioma (MM) on serous effusion is challenging due to significant morphologic overlap with reactive mesothelial cells and adenocarcinoma. One of the morphologic features of MM in effusion cytology, small orangiophilic squamous‐like cells (SOSLC), has received little attention. To the best of the authors' knowledge, the current study is the first to assess the sensitivity and specificity of SOSLC in serous effusion specimens from histology‐proven MM cases along with those of reactive mesothelial and adenocarcinoma cases.METHODSA total of 130 cases of pleural (86 cases) and peritoneal (44 cases) effusion cytology cases (30 with histology‐proven MM, 41 with adenocarcinoma, and 59 with reactive mesothelial cells) were studied. The presence or absence of SOSLC was recorded in each case.RESULTSThe cytological diagnoses of the 30 histology‐proven MM cases included 1) atypical mesothelial cells, favor reactive (4 cases); 2) atypical mesothelial cells, suspicious for or cannot exclude mesothelioma (18 cases); and 3) positive for MM (8 cases). SOSLC were found in 10 of the 30 MM effusion cases (33.3%), 1 of the 41 adenocarcinoma cases (2.4%), and 5 of the 59 reactive mesothelial cell cases (8.5%). SOSLC were more likely to be present in MM effusions compared with either adenocarcinoma (P < .0001) or reactive mesothelial cell (P < .02) effusions. All 10 cases of MM with SOSLC were from pleural fluids. One case of peritoneal serous adenocarcinoma had SOSLC and 5 cases of reactive mesothelial cells in peritoneal fluid were found to have SOSLC.CONCLUSIONSAlthough not sensitive, the presence of SOSLC is quite specific for MM in pleural fluid cytology specimens. Finding this morphological feature in pleural fluid should alert the pathologist to a possible diagnosis of MM.Cancer (Cancer Cytopathol) 2014;122:70–75. © 2013 American Cancer Society.