Compilation and arrangement: Wei Jianguo, Wang Qiang's molecular pathology has made rapid progress and has entered our daily pathological diagnosis practice to a certain extent, and salivary gland pathology is no exception. Seethala, a pathologist at the University of Pittsburgh Medical Center, has published a review in the journal Arch Pathol Lab Med, detailing some knowledge points about the molecular changes of salivary gland tumors since the fifth edition of the WHO classification of head and neck tumors. In order to help you better understand the relevant issues and guide clinical practice, we have compiled and introduced the key points of this article as follows.
Molecular alterations may facilitate reclassification of disease species
In the fifth edition of the WHO classification, the most classic name and classification revision is to change the name of sclerosing polycystic adenosis (SCELOROSING polycystic adenosis, which was previously classified as non-tumor) to sclerosing polycystic adenoma (SPA) and treat it as a benign tumor.
SPA was initially thought to be a pseudoneoplastic lesion mimicking fibrocystic or sclerosing adenosis of the breast. Most of the tumors occur in the parotid gland of patients aged 30-40 years, and it is more common in women; Rarely, it is associated with genetic polycystic lesions and Cowden syndrome. In general, the spa boundary is clear, and there is generally a capsule, and the section is grayish and pale, with cystic manifestations of varying degrees.
Histologically, the spa has a sclerotic appearance, often with cystic areas of varying severity, the cyst cavity lined with vacuolar "foamy" cells with apocrine ductal components and abnormal serous acinar with coarse red zymogen granules. Apocrine components may be proliferative and atypical to intraductal carcinoma, but progression to invasive carcinoma is extremely rare.
Figure 1Sclerosing polycystic adenoma. (a) the general realm is clear and has hardening; (b) cystic of varying severity, with the cavity lined with vacuole-like, "foamy" cells; Apocrine ductal components (c) and abnormal serous acinar with red zymogen granules may also be present.
Because it was originally classified as non-neoplastic, the 2003 study reported a local ** rate of 29% (5 16), even exceeding many low-grade malignancies. However, ** cases are generally not completely resected, and the rate of this tumor ** is currently considered to be about 10%.
In 2006, a study proposed that SPA may be a neoplastic lesion through molecular biology methods (human androgen receptor analysis - non-random X inactivation); In addition, at least three cases have been reported to have progressed to invasive cancer. The basis of these studies, coupled with the subsequent confirmation of PI3 K PTEN AKT alterations, has led to the process of treating SPA as neoplastic. In fact, it has also been found that there is a close relationship between this disease and other apocrine gland lesions (such as intraductal carcinoma of the apocrine glands and apocrine carcinoma of the salivary ducts). In short, the practice of reclassifying SPA as adenoma more accurately reflects its biological behavior, and complete resection is required clinically to minimize the probability of **, and pathologists should report the status of the resection margins.
Molecular alterations may help to re-understand certain diseases
In the past, mucinous adenocarcinoma was considered a separate disease, but in the fourth edition of the WHO classification, it is classified as adenocarcinoma and non-specific type. However, due to the in-depth understanding of morphological and molecular characteristics, the fifth edition of the WHO classification has been modified to be classified as provisional classification. At the current location, the so-called tentative type is still excluding the situation after the transfer and the existing classification.
Mucinous adenocarcinoma occurs in patients aged 70 to 80 years, and there is no gender difference, and small salivary glands are more common. Histologically, it is generally solid, papillary, signet ring cell hyperplasia, and the tumor cells are moderately pleomorphic; The background is mucus-like, often referred to as "gelatinous" depending on the degree of mucus-like manifestation.
One condition associated with mucinous adenocarcinoma is intraductal papillary mucinous tumors of the salivary glands, because some of the same name is similar to the pancreas. Unlike mucinous adenocarcinoma, intraductal papillary mucinous tumors in the salivary ducts are of lower grade and less invasive, with very little extracellular mucus surrounding the tumor nest. However, both tumors are characterized by the common AKT1 PE17k mutation; Unlike intraductal papillary mucinous tumors, mucinous adenocarcinoma also has a common TP53 mutation, suggesting that the former is of low grade. In addition, the salivary mucus acinar differentiation marker NKX31. Papillary mucinous tumors in the salivary ducts are strongly positive. The original authors of this article said that they had also noticed that mucinous adenocarcinoma and microsecretory adenocarcinoma expressed this marker, indicating that this is a type of mucinous acinar differentiated tumor.
Figure 2Mucinous adenocarcinoma of the salivary gland and papillary mucinous neoplasm in the salivary duct. (a) Mucinous adenocarcinoma of the salivary gland, with solid, papillary growth, mucinous goblet cells, more eosinophilic invasive manifestations, and more pronounced atypical features of the cells (below). (b, c) Papillary mucinous tumor in the salivary ductal duct with clear boundaries and cells in an eosinophilic to mucinous form with a single columnar epithelium with a stratified nucleus. Immunohistochemistry NKX31 strong positive, suggesting a mucinous acinar phenotype.
About 1 in 4 cases of mucinous adenocarcinoma may metastasize, which is related to signet ring cell morphology, and/or colloidal morphology. Papillary mucinous tumors in the salivary ductal ducts are actually of lower grade and more biologically indolent.
In conclusion, mucinous adenocarcinoma is no longer a tentative diagnosis, and AKT1 P. is presentThe E17K mutation actually supports its primary nature, NKX3A positive 1 indicates mucoacular acinar differentiation.
To be continued
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References
1]seethala rr. new entities and concepts in salivary gland tumor pathology: the role of molecular alterations. arch pathol lab med. 2023;10.5858/arpa.2023-0001-ra.
doi:10.5858/arpa.2023-0001-ra