Herpes Proctitis in Men Mimicking Rectal Adenocarcinoma: Two Cases of an Easily Overlooked Diagnosis in the Proximal Rectum.

We describe two cases of rectal herpes simplex virus (HSV) infection in men that clinically mimicked rectal adenocarcinoma. Herpes infection in this location more commonly presents as an anal mass with viral inclusions in squamous epithelial cells. We report these cases to increase awareness of the unusual presentation as a proximal rectal mass with viral inclusions in endothelial cell nuclei. One patient was HIV-positive, and the other one had a history of having sex with men (MSM). Both patients had a thickened rectal wall with prominent lymphadenopathy on computed tomography (CT) scan, suspecting for malignancy. Biopsy showed abundant granulation tissue, necrosis, and inflammatory infiltrate composed predominantly of lymphocytes with admixed numerous plasma cells, eosinophils, and neutrophils. Rare granulation tissue vessels were lined by endothelial cells with nuclear molding and chromatin margination, and nuclei that were positive for HSV immunohistochemistry (IHC). One patient had confirmatory viral culture from biopsy of the ulcerated rectal mass. Both patients had symptom resolution following treatment for HSV. HSV should be considered in the differential diagnosis of rectal inflammatory masses, particularly in immunocompromised, HIV-positive, and MSM patients.

Whole Slide Imaging Versus Microscopy for Primary Diagnosis in Surgical Pathology: A Multicenter Blinded Randomized Noninferiority Study of 1992 Cases (Pivotal Study).

Most prior studies of primary diagnosis in surgical pathology using whole slide imaging (WSI) versus microscopy have focused on specific organ systems or included relatively few cases. The objective of this study was to demonstrate that WSI is noninferior to microscopy for primary diagnosis in surgical pathology. A blinded randomized noninferiority study was conducted across the entire range of surgical pathology cases (biopsies and resections, including hematoxylin and eosin, immunohistochemistry, and special stains) from 4 institutions using the original sign-out diagnosis (baseline diagnosis) as the reference standard. Cases were scanned, converted to WSI and randomized. Sixteen pathologists interpreted cases by microscopy or WSI, followed by a wash-out period of ≥4 weeks, after which cases were read by the same observers using the other modality. Major discordances were identified by an adjudication panel, and the differences between major discordance rates for both microscopy (against the reference standard) and WSI (against the reference standard) were calculated. A total of 1992 cases were included, resulting in 15,925 reads. The major discordance rate with the reference standard diagnosis was 4.9% for WSI and 4.6% for microscopy. The difference between major discordance rates for microscopy and WSI was 0.4% (95% confidence interval, -0.30% to 1.01%). The difference in major discordance rates for WSI and microscopy was highest in endocrine pathology (1.8%), neoplastic kidney pathology (1.5%), urinary bladder pathology (1.3%), and gynecologic pathology (1.2%). Detailed analysis of these cases revealed no instances where interpretation by WSI was consistently inaccurate compared with microscopy for multiple observers. We conclude that WSI is noninferior to microscopy for primary diagnosis in surgical pathology, including biopsies and resections stained with hematoxylin and eosin, immunohistochemistry and special stains. This conclusion is valid across a wide variety of organ systems and specimen types.

High prevalence of inflammatory bowel disease in United States residents of Indian ancestry.

BACKGROUND & AIMS: It is unclear whether the reported low prevalence of inflammatory bowel disease (IBD) in Southern and Eastern Asia is real (caused by genetic or environmental factors) or spurious (because of differences in awareness of the condition among physicians or different interpretations of endoscopic and histologic features). We aimed to estimate the prevalence of IBD in patients of different ethnicities who underwent endoscopy in the United States, with ileocolonic biopsies evaluated by a single group of gastrointestinal pathologists. METHODS: We used a national pathology database to collect data on 1,027,977 subjects who underwent colonoscopy with ileocolonic biopsies from January 2008 through December 2013 throughout the United States; mucosal biopsy specimens were evaluated and reported by 1 group of 35 histopathologists. Patients were stratified into the following ancestries: Indian (persons with ancestry in the Indian subcontinent), East Asian (China, Korea, Japan, and Vietnam), Hispanic, Jewish, and Other. The prevalence of ulcerative colitis (UC), Crohn's disease (CD), and indeterminate colitis was determined for each ethnic group. RESULTS: In the study population, 30,812 patients were diagnosed with IBD (20,308 with UC, 7706 with CD, and 2798 with indeterminate colitis). UC was more commonly associated with Indian and Jewish ethnicity and less commonly associated with East Asian and Hispanic ethnicity. Similar patterns also applied to CD and to all types of IBD analyzed jointly. Among Indian patients, 11.7% of those of Gujarati origins had IBD, compared with 7.9% of other Indians (odds ratio, 1.5; 95% confidence interval, 1.14-2.11). CONCLUSIONS: Patients of Indian origin living in the United States have a greater risk for all types of IBD than other American populations. East Asians and Hispanics have a lower risk, possibly similar to that of the populations still living in their original countries. These findings may have relevance to the practice of gastroenterology in countries where there are sizable portions of the population with roots in the Indian subcontinent.

The immunohistochemical profile of atypical eosinophilic syncytial changes vs serous carcinoma.

Endometrial epithelial cytoplasmic change (EECC) is an adaptive cytoplasmic change commonly seen in the endometrium. Previously considered "metaplasia," EECC is now the preferred term because it offers a descriptive designation without implying a specific mechanism of development. There are 5 types of EECC: squamous, ciliated cell, eosinophilic, mucinous, and secretory (clear cell and hobmail cell) changes. Eosinophilic syncytial change (ESC) is a similar but unrelated degenerative change seen in endometrial breakdown. Some cases of ESC show atypical cytologic features that may resemble endometrial adenocarcinoma. Thirteen endometrial biopsy and curettage specimens with atypical ESCs (AESCs) were compared against 10 hysterectomy specimens with endometrial serous carcinoma. Clinical information and immunohistochemical staining profiles for markers phosphatase and tensin homologue deleted on chromosome 10 (PTEN), p53, and Ki-67 were evaluated in each case. All 13 cases of AESC (100%) showed moderate-to-strong staining for PTEN, whereas PTEN expression was absent in all endometrial serous carcinomas (P < .001). Seven cases of AESC (54%) showed focal, weak positivity for p53, whereas all cases of serous carcinoma (100%) showed strong staining (P < .001). The Ki-67 index was low (3%-15%) and found in only 3 cases in AESC (32%) but was high (60%-90%) in all cases of endometrial serous carcinoma (100%) (P < .001). Atypical ESC and serous carcinoma share several morphological features on hematoxylin and eosin-stained sections that may complicate accurate diagnosis. The PTEN, p53, and Ki-67 staining profile can effectively distinguish between AESC and malignancy in difficult cases, providing an invaluable tool for a challenging diagnostic dilemma.

Adenoid cystic carcinoma.

Adenoid cystic carcinoma is a malignant tumor with a deceptively benign histologic appearance characterized by indolent, locally invasive growth with high propensity for local recurrence and distant metastasis. The tumor is composed of basaloid cells with small, angulated, and hyperchromatic nuclei and scant cytoplasm arranged into 3 prognostically significant patterns: cribriform, tubular, and solid. Some tumors undergo dedifferentiation into a high-grade form. Numerous studies have attempted to elucidate accurate histologic prognostic features but have often yielded conflicting results. Microarray analysis and gene expression profiling have provided new potential diagnostic and prognostic markers. However, tumor grade, stage, lymph node metastasis, invasion of major nerves, and margin status remain the most consistent predictors of prognosis. The combination of surgery and postoperative radiation therapy has improved locoregional control of the disease. Despite this achievement, late local recurrence and distant metastasis rates remain high and may occur decades after initial diagnosis.

Poorly differentiated gastroenteropancreatic neuroendocrine carcinoma associated with X-linked hyperimmunoglobulin M syndrome.

Gastroenteropancreatic neuroendocrine tumors are uncommon tumors representing 2% of all gastrointestinal tumors. We report a case of a 21-year-old man with X-linked hyperimmunoglobulin M (hyper-IgM) syndrome who presented with diarrhea and jaundice. An ultrasound and magnetic resonance imaging showed multiple variable-sized lesions in the liver and peripancreatic lymphadenopathy. The morphologic and immunohistochemical features of the biopsies from the liver and lymph node were consistent with poorly differentiated neuroendocrine carcinoma. Hyper-IgM syndrome is a rare primary immunodeficiency disease characterized by low serum IgG, IgA, and IgE levels with normal or elevated IgM levels. These patients are at a higher risk for developing malignancies, particularly adenocarcinoma of the gastrointestinal tract and lymphoma. A review of the literature of gastroenteropancreatic neuroendocrine tumors is presented with the discussion of a possible relationship of these tumors with immunodeficiency.