Gastric cancer, a group of common malignancies, results in the most cancer mortality worldwide after only lung and colorectal cancer. Although familial gastric cancers have long been recognized, it was not until recently that they were discovered to be associated with mutations of specific genes. Mutations of CDH1, the gene encoding E-cadherin, are the most common germline mutations detected in gastric cancer and underlie hereditary diffuse gastric cancer (HDGC) syndrome. All reported HDGCs are the pure diffuse type by Lauren classification and are associated with dismal prognosis once the tumor invades the submucosa. Because CDH1 germline mutations are inherited in an autosomal-dominant fashion and have high penetrance, the International Gastric Cancer Linkage Consortium (IGCLC) developed criteria to facilitate the screening of CDH1 mutation carriers; these criteria have been proven to have excellent sensitivity and specificity. Recent histologic studies suggest that HDGC progresses through several stages. Even when the tumor becomes “invasive” in lamina propria, it may stay indolent for a long time. However, the molecular mechanisms that induce the transitions between stages and determine the length of the indolent phase remain to be determined. Although the standard management for CDH1 mutation carriers is prophylactic total gastrectomy, many questions must be answered before the surgery can be done. These include the optimal surveillance strategy, the best strategy to choose surgical candidates, and the ideal time to perform surgery. In addition to increasing the risk of gastric cancer, CDH1 germline mutations also increase the risk of invasive lobular carcinoma of the breast, and possibly colorectal adenocarcinoma, and are associated with blepharocheilodontic syndrome (a congenital development disorder). However, the optimal management of these conditions is less established owing to insufficient data regarding the risk of cancer development. This review focuses on molecular and histological findings in HDGC, as opposed to sporadic diffuse gastric cancer, and their implications for the management of CDH1 mutation carriers and the diagnosis and treatment of HDGC. Other conditions associated with CDH1 germline mutations and future research directions are also discussed.

The manifestations of cutaneous leishmaniasis are broad and may mimic other inflammatory and neoplastic diseases. Pathologists and dermatologists should be aware of such pitfalls and can utilize PCR to confirm the diagnosis of leishmaniasis.

BACKGROUND: Columnar cell lesions are frequently associated with atypical ductal hyperplasia, lobular neoplasia, and tubular carcinoma, and have been suggested as a precursor lesion for low-grade carcinomas. However, in longterm follow-up studies, columnar cell lesions are associated with only a slight increase in later breast cancer development. If columnar cell lesions are precursor lesions, one would expect subsequent cancers to develop at the same site as the biopsy and to be preferentially of low grade. The goal of this article is to review the clinical and pathologic features of carcinomas that develop after a diagnosis of columnar cell lesion to try to establish whether these lesions are precursors to low-grade invasive carcinoma. METHODS: The authors reviewed biopsies containing columnar cell lesions, using the criteria of Schnitt and Vincent-Salomon, from 77 women in the Nashville Breast Cohort who developed subsequent breast carcinoma. Clinicopathologic features including laterality, type, and grade of the subsequent cancer were recorded. RESULTS: Breast cancer developed a median of 11 years after initial biopsy. The median age at diagnosis was 60 years. The majority of invasive carcinomas were of no special type and of intermediate grade. Moreover, the carcinomas were as likely to occur in the contralateral breast as in the breast that was originally diagnosed with columnar cell lesion, regardless of columnar cell lesion subtype (P ¼ .48). CONCLUSIONS: Carcinoma subsequent to columnar cell lesions may occur in either breast and tends to show a similar grade and type distribution as sporadic breast cancer. These findings argue against columnar cell lesions being a true precursor for lowgrade invasive carcinoma.

Summary Introduction: Chondro-osseous respiratory epithelial adenomatoid hamartoma (COREAH) is a benign lesion of the nose and sinuses that is extremely rare, with only 2 cases reported in the literature to date. Case report: We present herein the third reported case of COREAH, in a 38-year-old woman who presented with left nasal obstruction and a mass in her left nasal cavity. The mass was completely resected endoscopically. Microscopic examination showed hamartomatous proliferation of respiratory-type glands with mucinous metaplasia admixed with numerous spicules of mature bone, characteristic of COREAH. Conclusion: COREAH is a benign hamartomatous proliferation of respiratory epithelium, submucosal glands, and chondro-osseous mesenchyme. The clinical differential diagnoses for such lesions include glandular hamartoma, inflammatory polyp, inverted papilloma, and low-grade sinonasal adenocarcinoma. Recognition of this lesion as benign despite its potentially worrisome radiographic appearance is important to avoid an unnecessarily radical surgical procedure.

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm of follicular dendritic cells, most commonly affecting the lymph nodes and extranodal soft tissues of the head and neck, but also potentially arising in any visceral organ. FDCS with its diverse morphologies raises an occasionally challenging differential of primary and metastatic tumors with overlapping histologic and immunohistochemical features. When involving the head and neck, FDCS may be confused with squamous cell carcinoma, undifferentiated carcinoma, extracranial meningioma, and variants of papillary thyroid carcinoma. We describe here a case of FDCS showing nuclear grooves, intranuclear pseudoinclusions, diffuse epithelial membrane antigen and focal cytokeratin staining, and the first documented report of positivity for thyroid transcription factor-1. A discussion of the differential diagnosis and potential diagnostic pitfalls in FDCS brought forth by thyroid transcription factor-1 immunoreactivity and a full review of clinicopathologic and immunohistochemical features of head and neck FDCS are presented.

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Lynch syndrome (LS) is associated with an increased risk for colorectal, endometrial, and ovarian carcinomas in women. Risk-reducing hysterectomy and bilateral salpingo-oophorectomy (RRHSO) has been shown to be a cost-effective form of management and prevention of gynecological malignancies in patients with LS. Studies of incidental gynecologic malignancies identified in RRHSO are limited. In addition, recommendations on optimal handling of this type of specimen have ranged from submitting for microscopic examination the entire endometrium, fallopian tubes and ovaries to submitting only routine representative sections of these organs. In this study, we present the clinicopathologic findings of 29 cases of LS patients that underwent risk-reducing gynecologic surgery at our institution over a period of 13 yr. Clinical-pathologic information was obtained from the patients’ charts and pathology reports. Significant pathologic abnormalities were identified in 17% (5/29) of cases, all showing endometrial hyperplasia. Four of them with atypical and 1 without atypical. All of our cases with endometrial pathology had significant findings on preoperative endometrial sampling. To further study the recommendation of in toto submission of the endometrium, ovaries and fallopian tubes and the utility of preoperative endometrial sampling, we undertook a literature review of all the reported cases of incidental pathologic findings identified in RRHSO. The findings of our cohort and the literature reviewed support in toto submission of endometrium, and adnexal structures in the absence of gross lesions. In addition, our findings show a definite benefit for preoperative endometrial sampling as part of the workup for LS patients undergoing RRHSO.

Extravascular migratory metastasis is a form of cancer metastasis in which tumor cells spread by tracking along the abluminal aspect of vessel walls without breaking the vascular endothelial lining or intraluminal invasion. This phenomenon has been extensively described in melanoma and is being increasingly recognized in other neoplasms. Various modalities of treatment, including radiation‐, chemo‐, targeted‐, and immune‐ therapies may potentially induce angiotropic behavior in neoplastic cells. Although there is a risk for tumor recurrence and metastasis, angiotropism may be under‐recognized and is rarely reported. Here, we report a case of recurrent poorly‐differentiated acantholytic squamous cell carcinoma of the scalp with extensive perineural invasion, previously treated with multiple therapies. There was multifocal extravascular cuffing of neoplastic cells around and focally involving the walls of small to medium‐caliber blood vessels within and surrounding the tumor, without obvious tumor intravasation. In addition, small subtle nests of neoplastic keratinocytes were noted along the abluminal aspect of a large‐caliber deep dermal blood vessel in an en‐face margin, away from the main tumor mass. Such involvement can be difficult to identify; and thus, may be missed particularly during intra‐operative frozen section evaluation, leading to false‐negative margins and is therefore, a diagnostic pitfall.