Immunohistochemical Analysis of Salivary Gland Tumors: Application for Surgical Pathology Practice

Abstract

Salivary gland tumors are relatively uncommon and there exists a considerable diagnostic difficulty owing to their diverse histological features in individual lesions and the presence of a number of types and variants, in addition to overlapping histological patterns similar to those observed in different tumor entities. The classification is complex, but is closely relevant to the prognostic and therapeutic aspects. Although hematoxylin-eosin staining is still the gold standard method used for the diagnosis, immunohistochemistry (IHC) can enhance the accuracy and be a helpful tool when in cases to investigate the subjects that cannot be assessed by histological examination, such as the cell nature and differentiation status, cell proliferation, and tumor protein expression. This review depicts on the practical diagnostic utility of IHC in salivary gland tumor pathology under the following issues: assessment of cell differentiation, focusing on neoplastic myoepithelial cells; discrimination of histologically mimic tumor groups; diagnosis of specific tumor types, e.g., pleomorphic adenoma, adenoid cystic carcinoma, and salivary duct carcinoma; and evaluation of malignancy and prognostic factors. IHC plays a limited, even though important, role in the diagnosis of salivary gland tumors, but is often useful to support the histological assessment. However, unfortunately few tumor type-specific markers are still currently available. For these reasons, IHC should be considered a method that can be used to assist the final diagnosis, and its results themselves do not directly indicate a definitive diagnosis.

MCM3 as a Novel Diagnostic Marker in Benign and Malignant Salivary Gland Tumors

“…However, some tumors demonstrate common histopathological features and subsequently definite diagnosis is very difficult. Therefore, using other pathologic techniques such as Immunohistochemistry (IHC) seems to be useful to discern similar tumors and support histological assessment (Nagao et al,2012). Proteins involved in cell cycle; play an important role in various biological events such as tumor formation and progression, therefore evaluation of proliferation markers are currently used to predict biological behavior and to differentiate benign from malignant tumors (Freeman et al, 1999).…”

Myoepithelioma of the Parotid Gland – Diagnosis and Surgical Treatment Difficulties: a Case Study

“…Nagao et al [27] also report immunohistochemical markers which are useful in salivary gland tumor diagnostics. Pan-cytokeratin (CK) [AE1/AE3], α-smooth muscle actin (SMA), calponin, muscle-specific actin (MSA), p63, CK14, glial fibrillary acidic protein (GFAP), S-100 protein, and vimentin, Ki-67 [MIB-1] are useful in the differentiation of myoepithelial tumors of the salivary glands.…”

“…Through immunohistochemistry, cases of myoepithelioma were shown to be reactive for epithelial markers (keratin and/or epithelial membrane antigen); about 90% expressed keratins (most often AE1/AE3 or PAN-K), about 90% S-100 protein, 50-60% epithelial membrane antigen, 40-50% glial fibrillary acidic protein, and 30-40% smooth muscle actin [25][26][27]. Pre-surgical diagnosis of myoepithelioma on the basis of cytological assessment of the fine-needle biopsy material and immunohistochemical examination of the smear, confirmed by the histopathological examination of excised neoplasm described by Das [28] suggests the possibility of rationalizing and shortening pre-surgical diagnostics.…”

“…Features that determine local malignancy of the neoplasm such as muscle infiltration beyond the salivary gland capsule, even in a case of lack of morphologic features of malignancy assessed in routine histopathological examination, are in favor of the need for vaster excision range, much wider than is assumed for benign neoplasms. Aggressive in relation to the surrounding tissues, the infiltrating growth of the neoplasm, which is often reported, can be a symptom of further local recurrence [25][26][27]. Neoplasm infiltration of the perineural spaces is reported much more rarely; reports mainly concern malignant myoepithelioma [29][30][31].…”

Efficacy of Fine Needle Aspiration Cytology in Diagnosis of Salivary Gland Tumors

“…Non-epithelial tumors are very rareabout 2-5% of all salivary tumor pathology. Although this classification is complex, it has advantages regarding the prognostic and therapeutic aspects, because the biological behavior of each tumor type is different [1,4].…”