Seminars in Diagnostic Pathology

Salivary gland-like tumors of the breast are rare neoplasms that share morphologic, immunophenotypic, and/or genetic features with their salivary gland counterparts, highlighting a shared underlying histopathogenesis in most cases. Salivary gland-like carcinomas included in the World Health Organization classification of breast tumors are adenoid cystic carcinoma, secretory carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, and the exceedingly rare polymorphous adenocarcinoma. These carcinomas are usually triple negative for estrogen receptor and progesterone receptor expression and HER2 overexpression, yet generally have favorable prognosis, in contrast to high-grade triple negative carcinomas of no special type...

Odontogenic lesions are a category of lesions, which are found to be arising from the remnants of the tooth-bearing tissues of the body, that can be cystic in nature as a result of degeneration or as a result of excessive proliferation of these cells, can result in the formation of odontogenic tumours which are found in gnathic bones in the body. Since their discovery in literature and the explanation provided for their pathogenesis, these lesions have been the subject of debate and controversy amongst researchers as well as practitioners...

Breast specimens are some of the more common specimens sent to the pathology laboratory for diagnosis. From a clinical perspective, the diagnoses fall into three broad categories: benign, atypical and malignant with patients then being managed according to established guidelines. However, the pathologic diagnosis can sometimes be challenging, and the distinction between these categories is sometimes far more subtle and subjective than non-pathologist may understand. One recurring diagnostic challenge in breast pathology is the diagnosis of atypical ductal hyperplasia (ADH) versus ductal carcinoma in situ (DCIS)...

Sclerosing Odontogrenic Carcinoma (SOC) is a recent addition to the category of odontogenic tumours, which was first described by Koutlas et al. in 2008. It was described as primary intraosseous carcinoma with bland cytology, sclerotic stroma with presence of local infiltration showing aggressive behaviour. Following its discovery and the presentation of first case, only a handful of cases have been reported till date, which may be due to underreporting of the cases or inclusion of the case to other diagnosis since the features of this tumour overlaps with many other lesions of the oral cavity...

The calcifying odontogenic cyst (COC) is an uncommon developmental odontogenic cyst, the oral counterpart of Malherbe's cutaneous calcifying epithelioma (pilomatricoma). This article presents two unique cases of calcifying odontogenic cysts each exhibiting distinctive histopathological features and its literature review. One case with an unexpected finding of cholesterol granuloma (CG), a rare occurrence in non-inflammatory cysts within an unusual location between two maxillary central incisors. One more instance involves the presence of a compound odontome in conjunction with COC...

For many years, odontogenic tumors have been known to present both clinical and histopathological challenges due to their origins in the epithelial, ectomesenchymal, and/or mesenchymal components of tooth-forming tissues. Gaining a comprehensive understanding of both common and rare odontogenic tumors is crucial for their effective study and clinical management. One particularly puzzling tumor is the "plexiform ameloblastoma," a variant of the solid multicystic ameloblastoma. This term describes a distinct pattern of epithelial proliferation within the cystic cavity...

BACKGROUND: The Calcifying Odontogenic Cysts (COC) displays a wide range of clinical and histopathological variations as well as diverse biological behaviors. This diversity has led to confusion and disagreement regarding the terminology and classification of this lesion. The previous classification attempts to categorize COC into two concepts. The first concept, termed "monistic," suggests that all COCs are neoplastic despite the majority being cystic in structure and seemingly non-neoplastic...

Appendiceal adenocarcinoma (ApAC) is a rare malignancy, comprising less than 1 % of all gastrointestinal tumors. The current World Health Organization classifies ApAC as mucinous or nonmucinous. Mucinous ApAC are composed of pools of mucin lined by cells with low- and high-grade cytology and areas of infiltrative invasion. Nonmucinous ApAC histologically resemble conventional colorectal adenocarcinomas and have a worse prognosis than their mucinous counterpart. Unfortunately, the nomenclature and histologic classification of ApAC, specifically the mucinous subtype, has changed several times throughout the years, contributing to diagnostic confusion for pathologists...

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Mucinous neoplasms of the appendix comprise a group of diagnostically challenging lesions that have generated significant controversy and confusion throughout the years, given their potential for aggressive behavior despite very bland cytologic features. Numerous classification schemes have been proposed to characterize and stage these lesions, but confusion remains among pathologists, surgeons, and oncologists regarding diagnostic criteria, therapeutic implications, and overall prognosis. This review summaries the current recommended nomenclature, histologic characteristics of each entity, and helpful features to distinguish neoplasia from benign mimics...

Appendix, considered a vestigial and disposable organ, has been long neglected as a source of abdominal tumors. Among the appendiceal tumors, goblet cell adenocarcinoma (GCA) is a rare primary epithelial neoplasm which has undergone multiple name changes and classifications in recent years, adding to confusion surrounding this unique amphicrine tumor. This entity was previously known as goblet cell carcinoid and adenocarcinoma ex goblet cell carcinoid. This review article provides an update on pathology, nomenclature, and recent classification systems with emphasis on 2019 World Health Organization Classification of Tumors, 3-tiered grading system...

Well-differentiated neuroendocrine tumors are the most common neoplasm of the appendix. They are graded and staged using World Health Organization and American Joint Committee on Cancer criteria, respectively. They may be invisible grossly or form rounded yellow nodules, sometimes in the appendiceal tip. They show classic neuroendocrine tumor features microscopically, forming nests and cords of monotonous cells with salt-and-pepper chromatin and amphophilic cytoplasm. They are positive for neuroendocrine markers by immunohistochemistry, but their molecular characteristics are not well defined...

Several neoplastic and non-neoplastic proliferations of the appendix can show varying degrees of serrated epithelial architecture. Of these, diffuse mucosal hyperplasia is most common, followed in frequency by low-grade mucinous and serrated neoplasms. It is important to distinguish serrated appendiceal neoplasms from their potential mimics because these entities may be managed differently. Diffuse mucosal hyperplasia is a non-neoplastic change that usually develops in the setting of resolving appendicitis and requires no further therapy or surveillance, and serrated neoplasms confined to the mucosa are adequately treated by appendectomy alone...

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Basaloid salivary gland neoplasms are a diverse and varied group of benign and malignant tumors. The term 'basaloid' is broadly used in reference to cells with elevated nuclear to cytoplasmic ratio, sparse cytoplasm, and hyperchromatic nuclei. However, a subset may also fit within the "small round blue cell tumor" morphologic category or the "biphasic" salivary gland tumor category. Furthermore, there are no established thresholds for the proportion of basaloid tumor cells needed to consider a tumor within the basaloid spectrum...

Achieving clear resection margins at the time of lumpectomy is essential for optimal patient outcomes. Margin status is traditionally determined by pathologic evaluation of the specimen and often is difficult or impossible for the surgeon to definitively know at the time of surgery, resulting in the need for re-operation to obtain clear surgical margins. Numerous techniques have been investigated to enhance the accuracy of intraoperative margin and are reviewed in this manuscript.

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Salivary gland neoplasms characterized by abundant mucin production are rare but have long been recognized. Due to their scarcity, precise classification has long eluded these mucin-rich tumors. Recent molecular discoveries, however, have shed considerable light on the genetic underpinnings of mucin-rich salivary gland neoplasms. This manuscript will review the most up-to-date information on this fascinating group of salivary gland neoplasms.

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Salivary gland tumors (SGT) display morphological diversity and pose diagnostic challenges. Preoperative fine needle aspiration cytology (FNAC) is a minimally invasive and efficient diagnostic test. However, due to the limited sample size, the final diagnosis may not be established based on FNAC alone. Although cytomorphology and architecture are usually preserved on FNAC, morphologic changes specific to FNAC can complicate the diagnosis. The Milan System for Reporting Salivary Gland Cytopathology categorizes complex FNAC interpretations...