Distinctive Pattern of Glial Fibrillary Acidic Protein Immunoreactivity Useful in Distinguishing Fragmented Pleomorphic Adenoma, Canalicular Adenoma and Polymorphous Low Grade Adenocarcinoma of Minor Salivary Glands

Article (PDF Available)inHead and Neck Pathology 1(1):27-32 · September 2007with136 Reads
DOI: 10.1007/s12105-007-0003-8 · Source: PubMed
Abstract
Immunohistochemistry (IHC) can be helpful in the diagnosis of minor salivary gland neoplasms including those that have been incisionally biopsied or fragmented during surgery that do not contain key diagnostic features on hematoxylin and eosin sections. IHC has been used as an adjunct to distinguish among many salivary gland neoplasms using both qualitative and quantitative methods. The objective of this study was to determine whether a distinctive immunoreactivity staining pattern to GFAP can be consistently observed among three selected minor salivary gland neoplasms and thus serve as a diagnostic adjunctive procedure. Glial fibrillary acidic protein (GFAP) reactivity was examined among 78 minor salivary gland neoplasms: 27 canalicular adenomas (CAA), 21 pleomorphic adenomas (PA) and 30 polymorphous low grade adenocarcinomas (PLGA). Each case was evaluated by two oral and maxillofacial pathologists (OMP) blinded to the diagnosis. Consensus was reached on the pattern of GFAP reactivity among the neoplastic cells and on the similarities and differences among the cases. Ninety-six percent (96%) of CAAs demonstrated a distinctive linear immunoreactive pattern among cells in proximity to connective tissue interface. All (100%) PAs demonstrated diffuse immunopositivity within tumor cells. All (100%) PLGAs showed little or no intralesional reactivity and no peripheral linear immunoreactivity. Additional challenge cases were examined by outside OMPs to demonstrate the utility of these findings. This study demonstrates that the pattern of GFAP immunoreactivity may be an adjunct to diagnosis among PA, CAA and PLGA. The pattern of distinctly linear GFAP immunoreactivity at the tumor/connective tissue interface in CAA has not been reported previously. This distinctive feature may permit the pathologist to differentiate among CAA, PA and PLGA when an incisional biopsy and/or fragmentation cause key diagnostic features to be absent. Because each of these neoplasms requires a different treatment approach, this can be of major significance.

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    • "These results were statistically not significant enough to make such a conclusion. However, an American study conducted by Curran et al. in 2007 concluded very convincing results in differentiating PA from PLGA, with GFAP showing intra lesional positivity in all cases of PA (n=21) while entirely negative in all cases of PLGA (n=30), it was proved by a highly significant p value of < 0.001 [20]. Likewise, in another study carried out by Deihimy et al., who looked for the GFAP staining in PA and mucoepidermoid carcinoma, their results of GFAP reactivity showed that the abluminal cells were diffusely positive for the marker in all cases of PA (n=25) and secondly it highlighted the chondromyxoid areas of PA [24]. "
    [Show abstract] [Hide abstract] ABSTRACT: Objective: To study the immunohistochemical pattern of CD 117, glial fibrillary acidic protein (GFAP), smooth muscle actin (SMA) and CD 43 in pleomorphic adenoma (PA), adenoid cystic carcinoma (AdCC) and polymorphous low grade adenocarcinoma (PLGA) of minor salivary glands. Materials and Methods: Twenty cases of PA, 20 cases of AdCC and 10 cases of PLGA were retrieved from record files along with their paraffin blocks at Armed Forces Institute of Pathology, Pakistan. New histological diagnosis was made on freshly prepared H&E sections followed by application and analysis of immunostains. Results: The mean age of the patients was 44 ± 15 (mean SD) (range; 17–86) years. There were 26 male and 24 female patients with a male to female ratio of 1.08:1. Fourteen cases of PA, 14 cases of AdCC and 6 cases of PLGA were positive for CD117. In case of GFAP, only 9 cases of AdCC and 3 cases of PLGA were positive; however, 16 cases of PA were also positive. Twelve cases of AdCC and 7 cases of PA were positive for SMA and half of the PLGA cases were also reactive. Nonetheless, the least expression was seen in case of CD 43, where only five cases of AdCC were positive. Six cases of PA and three cases of PLGA were also positive. Conclusion: Our results suggest that the use of GFAP, SMA, CD 117 and CD 43 as an adjunct to histological examination is not helpful in differentiating PA, AdCC and PLGA from one another.
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    • "In addition, basal cell adenoma, pleomorphic adenoma, epithelial-myoepithelial carcinoma, polymorphous low-grade adenocarcinoma, low-grade cribriform cystadenocarcinoma, basal cell adenocarcinoma, and sialoblastoma also need to be considered in the differential diagnosis. The IHC-based differential diagnosis is shown inFigure 5, whereas only the clinical and morphological assessments can adjudicate the final diagnosis for some of the tumors [11, 13, 14, 49, 59, 66, 70]. For example, among α-SMA/calponin-positive tumors, distinction between adenoid cystic carcinoma (Fig. 6A) and basal cell adenoma (Fig. 6C) is sometimes challenging based on histological examination alone. "
    [Show abstract] [Hide abstract] 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.
    Full-text · Article · Oct 2012
  • [Show abstract] [Hide abstract] ABSTRACT: We report a peculiar case of canalicular adenoma of the upper lip in a 57-year-old woman, presenting as two distinct asymptomatic nodules diagnosed and treated surgically within a 2-year period.
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